Artículos de revistas: "Amines"

1

Budynina, Ekaterina, Konstantin Ivanov, Ivan Sorokin y Mikhail Melnikov. "Ring Opening of Donor–Acceptor Cyclopropanes with N-Nucleophiles". Synthesis 49, n.º 14 (18 de mayo de 2017): 3035–68. http://dx.doi.org/10.1055/s-0036-1589021.

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Ring opening of donor–acceptor cyclopropanes with various N-nucleophiles provides a simple approach to 1,3-functionalized compounds that are useful building blocks in organic synthesis, especially in assembling various N-heterocycles, including natural products. In this review, ring-opening reactions of donor–acceptor cyclopropanes with amines, amides, hydrazines, N-heterocycles, nitriles, and the azide ion are summarized.1 Introduction2 Ring Opening with Amines3 Ring Opening with Amines Accompanied by Secondary Processes Involving the N-Center3.1 Reactions of Cyclopropane-1,1-diesters with Primary and Secondary Amines3.1.1 Synthesis of γ-Lactams3.1.2 Synthesis of Pyrroloisoxazolidines and -pyrazolidines3.1.3 Synthesis of Piperidines3.1.4 Synthesis of Azetidine and Quinoline Derivatives3.2 Reactions of Ketocyclopropanes with Primary Amines: Synthesis of Pyrrole Derivatives3.3 Reactions of Сyclopropane-1,1-dicarbonitriles with Primary Amines: Synthesis of Pyrrole Derivatives4 Ring Opening with Tertiary Aliphatic Amines5 Ring Opening with Amides6 Ring Opening with Hydrazines7 Ring Opening with N-Heteroaromatic Compounds7.1 Ring Opening with Pyridines7.2 Ring Opening with Indoles7.3 Ring Opening with Di- and Triazoles7.4 Ring Opening with Pyrimidines8 Ring Opening with Nitriles (Ritter Reaction)9 Ring Opening with the Azide Ion10 Summary

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2

Barham, Joshua P. y Jaspreet Kaur. "Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals". Synthesis 54, n.º 06 (25 de octubre de 2021): 1461–77. http://dx.doi.org/10.1055/a-1677-6619.

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AbstractAmines and amides, as N-containing compounds, are ubiquitous in pharmaceutically-active scaffolds, natural products, agrochemicals, and peptides. Amides in nature bear a key responsibility for imparting three-dimensional structure, such as in proteins. Structural modifications to amines and amides, especially at their positions α to N, bring about profound changes in biological activity oftentimes leading to more desirable pharmacological profiles of small drug molecules. A number of recent developments in synthetic methodology for the functionalizations of amines and amides omit the need of their directing groups or pre-functionalizations, achieving direct activation of the otherwise relatively benign C(sp3)–H bonds α to N. Among these, hydrogen atom transfer (HAT) has proven a very powerful platform for the selective activation of amines and amides to their α-amino and α-amido radicals, which can then be employed to furnish C–C and C–X (X = heteroatom) bonds. The abilities to both form these radicals and control their reactivity in a site-selective manner is of utmost importance for such chemistries to witness applications in late-stage functionalization. Therefore, this review captures contemporary HAT strategies to realize chemo- and regioselective amine and amide α-C(sp3)–H functionalization, based on bond strengths, bond polarities, reversible HAT equilibria, traceless electrostatic-directing auxiliaries, and steric effects of in situ-generated HAT agents.1 Introduction2 Functionalizations of Amines3 Functionalizations of Carbamates4 Functionalizations of Amides5 Conclusion

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3

Manthey, MK, SG Pyne y RJW Truscott. "Addition of Aliphatic and Aromatic Amines to Catechol in Aqueous Solution Under Oxidizing Conditions". Australian Journal of Chemistry 42, n.º 3 (1989): 365. http://dx.doi.org/10.1071/ch9890365.

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The oxidation of catechol in the presence of two aliphatic and aromatic amines has been investigated. In aqueous solutions of pH 7.0 and 11.7, the substitution pattern of the adduct was dependent on the type of amine used. Aromatic amines produced 4,5-disubstituted o-quinones, whereas aliphatic amines gave either 2,4,5-trisubstituted or 2,4-disubstituted o-quinone adducts. A rationale based upon the stability of vinylogous amides is presented to account for the observed substitution pattern.

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4

Os, Van M., Van A. M. Vuuren y S. F. Spoelstra. "Mechanisms of adaptation in sheep to overcome silage intake depression induced by biogenic amines". British Journal of Nutrition 77, n.º 3 (marzo de 1997): 399–415. http://dx.doi.org/10.1079/bjn19970041.

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Effects of biogenic amines on silage intake and rumen fermentation during dietary changes were studied in sheep. Two direct-cut grass silages were prepared from a single grass sward, one untreated (WAS) and one treated with 4·0 litres formic acid (850 ml/1) per tonne (FAS). Diets of FAS, and FAS supplemented with 7·2 g biogenic amined/kg DM (FAS +A), were offered ad libitum, once daily to four rumen-cannulated, and four intact wethers in a repeated crossover design experiment. During a pre-period before each crossover, the animals were offered either the silage low in biogenic amines (FAS), or that containing moderate concentrations (WAS). During the first 4 d of the FAS+A treatment, the added biogenic amins tended to lower daily DM intake (DMI) and lowered significantly the DMI during the principal meal after feeding. This acute effect on DMI tended to be reduced when the sheep were previously preconditioned to amines by feeding WAS, and the acute DMI depression during the principal meal was significantly reduced. At the end of the 14 d FAS+A feeding period daily DMI was similar to that of the FAS treatment, but the daily pattern of intake remained different, with lower intake of FAS+A during the first 5 h after feeding, this being compensated for by the end of the day. Rumen fermentation tended to be less during the first 4 d that FAS+A was offered, due to the lower DMI and not due to the acute effect of amines. However, in the sheep unadapted to FAS+A, amine content in the rumen was higher than when the sheep were adapted for 14 d to FAS+A or WAS. Adaptation to FAS+A and feeding WAS during the pre-periods, increased the amine-degrading capacity of rumen fluid. In conclusion, in sheep unadapted to dietary amines, feeding amines will acutely lower DMI through reduced palatibility and most probably by stressing intermediary metabolism. Being preconditioned to amines slightly reduces the acute effect on daily DMI. Although the sheep adapted within 14 d to biogenic amines in the diet and increased daily DMI, there was clear evidence that amines have a negative effect on palatability.

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5

Saha, Sayantani y Moris S. Eisen. "Mild catalytic deoxygenation of amides promoted by thorium metallocene". Dalton Transactions 49, n.º 36 (2020): 12835–41. http://dx.doi.org/10.1039/d0dt02770g.

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The organoactinide-catalyzed (Cp*₂ThMe₂) hydroborated reduction of a wide range of tertiary, secondary, and primary amides to the corresponding amines/amine–borane adducts via deoxygenation of the amides is reported herein.

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6

Yedage, Subhash L., Denvert S. D'silva y Bhalchandra M. Bhanage. "MnO2 catalyzed formylation of amines and transamidation of amides under solvent-free conditions". RSC Advances 5, n.º 98 (2015): 80441–49. http://dx.doi.org/10.1039/c5ra13094h.

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7

Leggio, A., E. L. Belsito, G. De Luca, M. L. Di Gioia, V. Leotta, E. Romio, C. Siciliano y A. Liguori. "One-pot synthesis of amides from carboxylic acids activated using thionyl chloride". RSC Advances 6, n.º 41 (2016): 34468–75. http://dx.doi.org/10.1039/c5ra24527c.

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8

Zhang, Qiao, Xiao-Tao Lin, Norihisa Fukaya, Tadahiro Fujitani, Kazuhiko Sato y Jun-Chul Choi. "Selective N-formylation/N-methylation of amines and N-formylation of amides and carbamates with carbon dioxide and hydrosilanes: promotion of the basic counter anions of the zinc catalyst". Green Chemistry 22, n.º 23 (2020): 8414–22. http://dx.doi.org/10.1039/d0gc02890h.

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A Zn(OAc)₂ catalyst bearing the 1,10-phenanthroline (phen) ligand was efficient in the N-formylation of organic amine derivatives (e.g., amines, amides, and carbamates) using carbon dioxide (CO₂) and hydrosilanes.

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9

Charron, Carlie L., Jade M. Cottam Jones y Craig A. Hutton. "Are Aminomethyl Thioesters Viable Intermediates in Native Chemical Ligation Type Amide Bond Forming Reactions?" Australian Journal of Chemistry 71, n.º 9 (2018): 697. http://dx.doi.org/10.1071/ch18198.

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The condensation of N-mercaptomethyl amines and thioesters is a potential route to amides, via aminomethyl thioester intermediates, in a native chemical ligation type process followed by self-cleavage of the ‘mercaptomethyl’ auxiliary. This paper describes investigations towards the preparation of aminomethyl thioesters, and subsequent conversion into amides, from a three-component coupling of formaldehyde, a thioacid, and an amine. Our studies suggest that while such intermediates may be formed en route to amides, no advantages are offered over the direct reaction of the amine and thioacid precursors.

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10

Yao, Lei, Ming-Yi Wang, Xin-Ke Wang, Yi-Jun Liu, Hang-Fei Chen, Jun Zheng, Wei Nie et al. "Detection of atmospheric gaseous amines and amides by a high-resolution time-of-flight chemical ionization mass spectrometer with protonated ethanol reagent ions". Atmospheric Chemistry and Physics 16, n.º 22 (23 de noviembre de 2016): 14527–43. http://dx.doi.org/10.5194/acp-16-14527-2016.

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Abstract. Amines and amides are important atmospheric organic-nitrogen compounds but high time resolution, highly sensitive, and simultaneous ambient measurements of these species are rather sparse. Here, we present the development of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) method, utilizing protonated ethanol as reagent ions to simultaneously detect atmospheric gaseous amines (C1 to C6) and amides (C1 to C6). This method possesses sensitivities of 5.6–19.4 Hz pptv−1 for amines and 3.8–38.0 Hz pptv−1 for amides under total reagent ion signals of ∼ 0.32 MHz. Meanwhile, the detection limits were 0.10–0.50 pptv for amines and 0.29–1.95 pptv for amides at 3σ of the background signal for a 1 min integration time. Controlled characterization in the laboratory indicates that relative humidity has significant influences on the detection of amines and amides, whereas the presence of organics has no obvious effects. Ambient measurements of amines and amides utilizing this method were conducted from 25 July to 25 August 2015 in urban Shanghai, China. While the concentrations of amines ranged from a few parts per trillion by volume to hundreds of parts per trillion by volume, concentrations of amides varied from tens of parts per trillion by volume to a few parts per billion by volume. Among the C1- to C6-amines, the C2-amines were the dominant species with concentrations up to 130 pptv. For amides, the C3-amides (up to 8.7 ppb) were the most abundant species. The diurnal and backward trajectory analysis profiles of amides suggest that in addition to the secondary formation of amides in the atmosphere, industrial emissions could be important sources of amides in urban Shanghai. During the campaign, photo-oxidation of amines and amides might be a main loss pathway for them in daytime, and wet deposition was also an important sink.

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11

Qu, Jing, Shishan Yu, Wenzhao Tang, Yunbao Liu, Yue Liu y Jing Liu. "Progress on Cassaine-Type Diterpenoid Ester Amines and Amides (Erythrophleum Alkaloids)". Natural Product Communications 1, n.º 10 (octubre de 2006): 1934578X0600101. http://dx.doi.org/10.1177/1934578x0600101005.

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The structures, spectral characteristics, and bioactivities of 39 natural cassaine-type diterpenoid ester amines and amides (Erythrophleum alkaloids) and 31 synthetic analogues are reviewed. Cassaine-type diterpenoid ester amines and amides, the so called Erythrophleum alkaloids, have the skeleton of cassane-type diterpenoids with a N-containing side chain, and are classified into two groups, ester amines and amides. Cassaine-type diterpenoid ester amines and amides show remarkable inotropic action on the heart, inhibition of Na+/K+-ATPase, cytotoxities, and other major bioactivities. Structural modification of cassaine-type diterpenoid ester amines and amides has been carried out to furnish many derivatives to study the structure-activity relationships.

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12

North, Michael. "Amines and amides". Journal of the Chemical Society, Perkin Transactions 1, n.º 16 (1999): 2209–29. http://dx.doi.org/10.1039/a903369f.

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13

North, Michael. "Amines and amides". Contemporary Organic Synthesis 1, n.º 6 (1994): 475. http://dx.doi.org/10.1039/co9940100475.

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14

North, Michael. "Amines and amides". Contemporary Organic Synthesis 2, n.º 4 (1995): 269. http://dx.doi.org/10.1039/co9950200269.

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15

North, Michael. "Amines and amides". Contemporary Organic Synthesis 3, n.º 4 (1996): 323. http://dx.doi.org/10.1039/co9960300323.

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16

North, Michael. "Amines and amides". Contemporary Organic Synthesis 4, n.º 4 (1997): 326. http://dx.doi.org/10.1039/co9970400326.

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17

North, Michael. "Amines and amides". Journal of the Chemical Society, Perkin Transactions 1, n.º 17 (1998): 2959–72. http://dx.doi.org/10.1039/a802125b.

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18

Malcolmson, Steven J., Kangnan Li y Xinxin Shao. "2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines". Synlett 30, n.º 11 (26 de marzo de 2019): 1253–68. http://dx.doi.org/10.1055/s-0037-1611770.

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The development of new strategies for the preparation of chiral amines is an important objective in organic synthesis. In this Synpacts, we summarize our approach for catalytically accessing nucleophilic aminoalkyl metal species from 2-azadienes, and its application in generating a number of important but elusive chiral amine scaffolds. Reductive couplings with ketones and imines afford 1,2-amino tertiary alcohols and 1,2-diamines, respectively, whereas fluoroarylations of gem-difluoro-2-azadienes deliver α-trifluoromethylated benzylic amines.1 Introduction2 Background: Umpolung Strategies for Preparing Chiral Amines3 Background: 2-Azadienes4 Reductive Couplings of 2-Azadienes5 Fluoroarylations of gem-Difluoro-2-azadienes6 Summary and Outlook

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19

Nodzewska, Aneta, Agnieszka Wadolowska, Katarzyna Podgorska, Damian Pawelski y Ryszard Lazny. "Synthesis of Solid-phase Supported Chiral Amines and Investigation of Stereoselectivity of Aldol Reactions of Amine-free Tropinone Enolate". Current Organic Chemistry 23, n.º 17 (2 de noviembre de 2019): 1867–79. http://dx.doi.org/10.2174/1385272823666190916145332.

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Seven selected chiral mono-, di-, and tridentate amines supported on insoluble polymer were effectively prepared from corresponding primary amines or secondary amino alcohols and Merrifield resin. The reaction of the polymer-supported amines with excess n-butyllithium gave the corresponding lithium amide bases, which were tested in the aldol reactions of tropinone with benzaldehyde. The deprotonation reactions were carried out with or without separation of the lithium enolate from polymer-supported reagents. Using the procedure with separation of lithium enolate from supported chiral reagent different results were obtained with or without the addition of LiCl despite the fact that aggregate formation of Merrifield resin supported Li-amides is hindered. Without the additive, the aldol products were obtained in low diastereoselectivity and enantioselectivity, whereas the addition of LiCl resulted in a significant increase of de and ee even when LiCl was added after the deprotonation step and separation of the chiral amine.

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20

Vejdělek, Zdeněk, Jiří Němec y Miroslav Protiva. "Synthesis of N-(1-phenyl-2-propyl)-2,5-diphenylpentylamine and some related compounds as potential neurotropic and cardiovascular drugs". Collection of Czechoslovak Chemical Communications 51, n.º 7 (1986): 1487–93. http://dx.doi.org/10.1135/cccc19861487.

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Heating of 2,5-diphenylvaleric acid with 2-phenylethylamine, 1-phenyl-2-propylamine, 1-phenyl-2-butylamine (IX), 1-(4-methoxyphenyl)-2-propylamine, 1-(4-methoxyphenyl)-2-butylamine (X) and 1-(4-dimethylaminophenyl)-2-propylamine to 200-210 °C resulted in the amides IIb-VIIb which were reduced with lithium aluminium hydride in boiling dibutyl ether to give the amines IIa, IIIa, and Va - VIIa. A similar two-step sequence starting from 4-phenyl-4-(phenylthio)-butyric acid and the amine IX gave compound VIIIa. The salts of the title amines revealed some central stimulating, antireserpine, thiopental potentiating, anticonvulsant, and antiarrhythmic effects. 1-(4-Dimethylaminophenyl)-2-butylamine (XI), prepared in this connection, proved anoretic activity.

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21

Xu, Qing, Huamei Xie, Er-Lei Zhang, Xiantao Ma, Jianhui Chen, Xiao-Chun Yu y Huan Li. "Selective catalytic Hofmann N-alkylation of poor nucleophilic amines and amides with catalytic amounts of alkyl halides". Green Chemistry 18, n.º 14 (2016): 3940–44. http://dx.doi.org/10.1039/c6gc00938g.

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A selective Hofmann N-alkylation reaction of amines/amides catalytic in alkyl halides is achieved by using alcohols as the alkylating reagents, affording mono- or di-alkylated amines/amides in high selectivities.

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22

Greenleaf, William B. y David N. Silverman. "Activation of the Proton Transfer Pathway in Catalysis by Iron Superoxide Dismutase". Journal of Biological Chemistry 277, n.º 51 (10 de octubre de 2002): 49282–86. http://dx.doi.org/10.1074/jbc.m208629200.

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Catalysis byEscherichia coliandPorphyromonas gingivalisiron superoxide dismutase was activated by addition of primary amines, as measured by pulse radiolysis and stopped-flow spectrophotometry. This activation was saturable for most amines investigated, and a free energy plot of the apparent second-order rate constant of activation was linear as a function of the pKaof the amine, indicating activation by proton transfer. Amines provide an alternate rather than the only pathway for proton transfer, and catalysis was appreciable in the absence of amines. Solvent hydrogen isotope effects were near unity for amine activation, which is consistent with rate-contributing proton transfer if the pKaof the proton acceptor on the enzyme is not in the region of the pKavalues of the amines studied, from 7.8 to 10.6. The activation of catalysis by these amines was uncompetitive with respect to superoxide, interpreted as proton transfer in a ternary complex of amine with the enzyme-bound peroxide dianion.

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23

Feng, Si Min y Qing Liu. "Research Progress of N-Alkylation of Alcohol and Amine by "Hydrogen Reaction"". Key Engineering Materials 871 (enero de 2021): 312–17. http://dx.doi.org/10.4028/www.scientific.net/kem.871.312.

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Amine compounds are widely found in natural products, pharmaceuticals and fine chemical products. Therefore, it is of great significance to develop methods for synthesizing amine compounds. Therefore, in recent years, a new method of synthesizing amines has been developed, namely "hydrogen borrowing reaction". This article reviews the alkylation of primary alcohols and amines, the cyclization of amino alcohols to form N-heterocyclic compounds, the reaction of diols and amines to form N-heterocyclic compounds, the reaction of alcohols and sulfonamides, and the reaction of alcohols and amines containing N heteroatoms , Alcohol and ammonia gas and ammonia to produce amine by hydrogen reaction research progress.

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24

Mah, Jae-Hyung, Young Park, Young Jin, Jun-Hee Lee y Han-Joon Hwang. "Bacterial Production and Control of Biogenic Amines in Asian Fermented Soybean Foods". Foods 8, n.º 2 (25 de febrero de 2019): 85. http://dx.doi.org/10.3390/foods8020085.

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Fermented soybean foods possess significant health-promoting effects and are consumed worldwide, especially within Asia, but less attention has been paid to the safety of the foods. Since fermented soybean foods contain abundant amino acids and biogenic amine-producing microorganisms, it is necessary to understand the presence of biogenic amines in the foods. The amounts of biogenic amines in most products have been reported to be within safe levels. Conversely, certain products contain vasoactive biogenic amines greater than toxic levels. Nonetheless, government legislation regulating biogenic amines in fermented soybean foods is not found throughout the world. Therefore, it is necessary to provide strategies to reduce biogenic amine formation in the foods. Alongside numerous existing intervention methods, the use of Bacillus starter cultures capable of degrading and/or incapable of producing biogenic amines has been proposed as a guaranteed way to reduce biogenic amines in fermented soybean foods, considering that Bacillus species have been known as fermenting microorganisms responsible for biogenic amine formation in the foods. Molecular genetic studies of Bacillus genes involved in the formation and degradation of biogenic amines would be helpful in selecting starter cultures. This review summarizes the presence and control strategies of biogenic amines in fermented soybean foods.

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25

Guo, Donglin, Yajamana Ramu, Angela M. Klem y Zhe Lu. "Mechanism of Rectification in Inward-rectifier K+ Channels". Journal of General Physiology 121, n.º 4 (17 de marzo de 2003): 261–76. http://dx.doi.org/10.1085/jgp.200208771.

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Rectification in inward-rectifier K+ channels is caused by the binding of intracellular cations to their inner pore. The extreme sharpness of this rectification reflects strong voltage dependence (apparent valence is ∼5) of channel block by long polyamines. To understand the mechanism by which polyamines cause rectification, we examined IRK1 (Kir2.1) block by a series of bis-alkyl-amines (bis-amines) and mono-alkyl-amines (mono-amines) of varying length. The apparent affinity of channel block by both types of alkylamines increases with chain length. Mutation D172N in the second transmembrane segment reduces the channel's affinity significantly for long bis-amines, but only slightly for short ones (or for mono-amines of any length), whereas a double COOH-terminal mutation (E224G and E299S) moderately reduces the affinity for all bis-amines. The apparent valence of channel block increases from ∼2 for short amines to saturate at ∼5 for long bis-amines or at ∼4 for long mono-amines. On the basis of these and other observations, we propose that to block the channel pore one amine group in all alkylamines tested binds near the same internal locus formed by the COOH terminus, while the other amine group of bis-amines, or the alkyl tail of mono-amines, “crawls” toward residue D172 and “pushes” up to 4 or 5 K+ ions outwardly across the narrow K+ selectivity filter. The strong voltage dependence of channel block therefore reflects the movement of charges carried across the transmembrane electrical field primarily by K+ ions, not by the amine molecule itself, as K+ ions and the amine blocker displace each other during block and unblock of the pore. This simple displacement model readily accounts for the classical observation that, at a given concentration of intracellular K+, rectification is apparently related to the difference between the membrane potential and the equilibrium potential for K+ ions rather than to the membrane potential itself.

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Zhou, Yongyun, Ruhima Khan, Baomin Fan y Lijin Xu. "Ruthenium-Catalyzed Selective Reduction of Carboxylic Esters and Carboxamides". Synthesis 51, n.º 12 (30 de abril de 2019): 2491–505. http://dx.doi.org/10.1055/s-0037-1611524.

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Amines and alcohols are important classes of building blocks in organic synthesis. The synthesis of these compounds has been a topic of interest. A straightforward method for their synthesis is the reduction of esters and amides to alcohols and amines, respectively. Various transition-metal catalysts have been developed for the homogeneous hydrogenation of esters and amides to alcohols and amines. In this review, an overview of the ruthenium-catalyzed selective hydrogenation of esters and amides is provided.1 General Introduction2 Ru-Catalyzed Reduction of Esters3 Ru-Catalyzed Selective Reduction of Amides4 Conclusions

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27

Zhao, J., J. N. Smith, F. L. Eisele, M. Chen, C. Kuang y P. H. McMurry. "Observation of neutral sulfuric acid-amine containing clusters in laboratory and ambient measurements". Atmospheric Chemistry and Physics Discussions 11, n.º 7 (11 de julio de 2011): 19729–68. http://dx.doi.org/10.5194/acpd-11-19729-2011.

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Abstract. Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a microscopic molecular scale (from molecular sizes up to 2 nm) have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfuric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to particle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectrometer designed for measuring neutral clusters formed in the atmosphere during nucleation. An experimental technique, which we refer to as Semi-Ambient Signal Amplification (SASA), was employed. Sulfuric acid was added to ambient air, and the concentrations and composition of clusters in this mixture were analyzed by the Cluster CIMS. This experimental approach led to significantly higher cluster concentrations than are normally found in ambient air, thereby increasing signal-to-noise levels and allowing us to study reactions between gas phase species in ambient air and sulfuric acid containing clusters. Mass peaks corresponding to clusters containing four H2SO4 molecules and one amine molecule were clearly observed, with the most abundant sulfuric acid-amine clusters being those containing a C2- or C4- amine (i.e., amines with masses of 45 and 73 amu). Evidence for C3- and C5- amines (i.e., amines with masses of 59 and 87 amu) was also found, but their correlation with sulfuric acid tetramer was not as strong as was observed for the C2- and C4- amines. The formation mechanisms for those sulfuric acid-amine clusters were investigated by varying the residence time in the inlet. It was concluded that the amines react directly with neutral clusters and that ion-induced clustering of sulfuric acid cluster ions with amines was not a dominant process. Results from ambient measurements have shown that the sulfuric acid-amine clusters were reasonably well correlated with sulfuric acid tetramer and consistent with the SASA experiments at the same Boulder sampling site. Also, clusters that contain C2- or C4- amines were more abundant and better correlated with sulfuric acid tetramer than other types of amine containing clusters. However, ambient measurements of sulfuric acid-amine clusters remain difficult and highly uncertain because their concentrations are only slightly above background levels, even during nucleation events.

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28

Zhao, J., J. N. Smith, F. L. Eisele, M. Chen, C. Kuang y P. H. McMurry. "Observation of neutral sulfuric acid-amine containing clusters in laboratory and ambient measurements". Atmospheric Chemistry and Physics 11, n.º 21 (2 de noviembre de 2011): 10823–36. http://dx.doi.org/10.5194/acp-11-10823-2011.

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Abstract. Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a microscopic molecular scale (from molecular sizes up to 2 nm) have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfuric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to particle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectrometer designed for measuring neutral clusters formed in the atmosphere during nucleation. An experimental technique, which we refer to as Semi-Ambient Signal Amplification (SASA), was employed. Sulfuric acid was added to ambient air, and the concentrations and composition of clusters in this mixture were analyzed by the Cluster CIMS. This experimental approach led to significantly higher cluster concentrations than are normally found in ambient air, thereby increasing signal-to-noise levels and allowing us to study reactions between gas phase species in ambient air and sulfuric acid containing clusters. Mass peaks corresponding to clusters containing four H2SO4 molecules and one amine molecule were clearly observed, with the most abundant sulfuric acid-amine clusters being those containing a C2- or C4-amine (i.e. amines with masses of 45 and 73 amu). Evidence for C3- and C5-amines (i.e. amines with masses of 59 and 87 amu) was also found, but their correlation with sulfuric acid tetramer was not as strong as was observed for the C2- and C4-amines. The formation mechanisms for those sulfuric acid-amine clusters were investigated by varying the residence time in the inlet. It was concluded that the amines react directly with neutral clusters and that ion-induced clustering of sulfuric acid cluster ions with amines was not a dominant process. Results from ambient measurements using the Cluster CIMS without addition of sulfuric acid have shown that the sulfuric acid-amine clusters were reasonably well correlated with sulfuric acid tetramer and consistent with the SASA experiments at the same Boulder sampling site. Also, clusters that contain C2- or C4-amines were more abundant and better correlated with sulfuric acid tetramer than other types of amine containing clusters. However, ambient measurements of sulfuric acid-amine clusters remain difficult and highly uncertain because their concentrations are only slightly above background levels, even during nucleation events.

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29

Otsuka, Rikuto, Kazuo Maruhashi y Tomohiko Ohwada. "Latent Brønsted Base Solvent-Assisted Amide Formation from Amines and Acid Chlorides". Synthesis 50, n.º 10 (20 de marzo de 2018): 2041–57. http://dx.doi.org/10.1055/s-0037-1609342.

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Weakly basic amines, including even neutral amines such as nitroaniline and aminocarboxylic acids, react with acid chlorides very efficiently in N,N-dimethylacetamide (DMAC), without addition of a base, to give the corresponding amides in high yields. The role of DMAC and related solvents as latent Brønsted bases was studied in these amidation reactions. Less basic amines, such as aromatic amines, reacted with benzoyl chloride faster than more basic aliphatic amines.

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30

Ma, Shuchao, Ben Ouyang, Linan Wang y Lei Yao. "Design and Biological Evaluation of 3-Aryl-4-alkylpyrazol-5-amines Based on the Target Fishing". Current Computer-Aided Drug Design 16, n.º 5 (9 de noviembre de 2020): 564–70. http://dx.doi.org/10.2174/1573409915666191003123900.

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Background: Pyrazol-5-amine derivatives are an important class of heterocyclic compounds. However, there are less 4-alkyl substituted pyrazoles reported. Objective: Here reported are the design, synthesis and biological evaluation of 3-aryl-4- alkylpyrazol-5-amines derivatives. Methods: A serials of 3-aryl-4-alkylpyrazol-5-amines were designed and the biological action targets were screened by target fishing function of Discovery Studio software. The synthesis route involved 3-oxo-3-arylpropanenitrile formation, alkylation, pyrazole formation, and amides formation. The antitumor activities of these compounds were carried out by thiazolyl blue tetrazolium bromide (MTT) method using U-2 OS (osteosarcoma) and A549 (lung cancer) tumor cells. Results: Eight 3-aryl-4-alkylpyrazol-5-amines were synthesized, and their structures were verified by 1H NMR, 13C NMR, and HRMS. Thirteen pharmacophores were mapped out by target fishing. Compound 5h showed anti-proliferation activities against U-2 OS and A549 tumor cell with IC50 value of 0.9 μM and 1.2 μM, respectively. Conclusion: Compound 5h might represent a promising scaffold for the further development of novel antitumor drugs.

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31

MARCOBAL, Á., P. J. MARTÍN-ÁLVAREZ, M. C. POLO, R. MUÑOZ y M. V. MORENO-ARRIBAS. "Formation of Biogenic Amines throughout the Industrial Manufacture of Red Wine". Journal of Food Protection 69, n.º 2 (1 de febrero de 2006): 397–404. http://dx.doi.org/10.4315/0362-028x-69.2.397.

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Changes in biogenic amines (histamine, methylamine, ethylamine, tyramine, phenylethylamine, putrescine, and cadaver-ine) were monitored during the industrial manufacture of 55 batches of red wine. The origin of these amines in relation to must, alcoholic fermentation, malolactic fermentation, sulfur dioxide addition, and wine aging and the interactions between amines and their corresponding amino acids and pH were statistically evaluated in samples from the same batches throughout the elaboration process. Some amines can be produced in the grape or the musts (e.g., putrescine, cadaverine, and phenylethylamine) or can be formed by yeast during alcoholic fermentation (e.g., ethylamine and phenylethylamine), although quantitatively only very low concentrations are reached in these stages (less than 3 mg/liter). Malolactic fermentation was the main mechanism of biogenic amine formation, especially of histamine, tyramine, and putrescine. During this stage, the increase in these amines was accompanied by a significant decline in their amino acid precursors. Significant correlations between biogenic amine formation and the disappearance of their corresponding amino acids were observed, which clearly supports the hypothesis that malolactic bacteria are responsible for accumulation of these amines in wines. No increase in the concentration of biogenic amines was observed after SO2 addition and during wine aging, indicating that sulfur dioxide prevents amine formation in subsequent stages.

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32

Bittner, Nataly, Andy Boon, Evert H. Delbanco, Christof Walter y Angela Mally. "Assessment of aromatic amides in printed food contact materials: analysis of potential cleavage to primary aromatic amines during simulated passage through the gastrointestinal tract". Archives of Toxicology 96, n.º 5 (5 de marzo de 2022): 1423–35. http://dx.doi.org/10.1007/s00204-022-03254-w.

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AbstractRecent analyses conducted by German official food control reported detection of the aromatic amides N-(2,4-dimethylphenyl)acetamide (NDPA), N-acetoacetyl-m-xylidine (NAAX) and 3-hydroxy-2-naphthanilide (Naphthol AS) in cold water extracts from certain food contact materials made from paper or cardboard, including paper straws, paper napkins, and cupcake liners. Because aromatic amides may be cleaved to potentially genotoxic primary amines upon oral intake, these findings raise concern that transfer of NDPA, NAAX and Naphthol AS from food contact materials into food may present a risk to human health. The aim of the present work was to assess the stability of NDPA, NAAX and Naphthol AS and potential cleavage to 2,4-dimethylaniline (2,4-DMA) and aniline during simulated passage through the gastrointestinal tract using static in vitro digestion models. Using the digestion model established by the National Institute for Public Health and the Environment (RIVM, Bilthoven, NL) and a protocol recommended by the European Food Safety Authority, potential hydrolysis of the aromatic amides to the respective aromatic amines was assessed by LC–MS/MS following incubation of the aromatic amides with digestive fluid simulants. Time-dependent hydrolysis of NDPA and NAAX resulting in formation of the primary aromatic amine 2,4-DMA was consistently observed in both models. The highest rate of cleavage of NDPA and NAAX was recorded following 4 h incubation with 0.07 M HCl as gastric-juice simulant, and amounted to 0.21% and 0.053%, respectively. Incubation of Naphthol AS with digestive fluid simulants did not give rise to an increase in the concentration of aniline above the background that resulted from the presence of aniline as an impurity of the test compound. Considering the lack of evidence for aniline formation from Naphthol AS and the extremely low rate of hydrolysis of the amide bonds of NDPA and NAAX during simulated passage through the gastrointestinal tract that gives rise to only very minor amounts of the potentially mutagenic and/or carcinogenic aromatic amine 2,4-DMA, risk assessment based on assumption of 100% cleavage to the primary aromatic amines would appear to overestimate health risks related to the presence of aromatic amides in food contact materials.

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33

Johnson, Nnadikwe, Wopara Onuoha FIdelis, Onyewudiala Ibeawuchi Julius, Udechukwu Mathew Chidubem y Ewelike Asterius Dozie. "Development Design of Amine Sweetening Unit Plant of Natural Gas". International Journal for Research in Applied Science and Engineering Technology 10, n.º 9 (30 de septiembre de 2022): 397–403. http://dx.doi.org/10.22214/ijraset.2022.46548.

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Abstract: In addition to reduced equipment sizes, lower circulation rates, and greater overall amine concentration, selective amines have become more popular for gas sweetening. Selective amines absorb H2S from CO2 through thermodynamic or kinetic processes. Selective amine mixtures may enable a small quantity of CO2 to remain in the treated gas. Plant capacity margins for selective amine units are frequently small. Increasing the acid gas concentration or throughput might result in sweet gas that does not fulfill CO2 specifications. Increasing the amine concentration, employing combinations of amines, and altering the lean amine temperature were explored since adding new equipment may be costly. Compared to increasing reboiler or pumping capacity, these factors need little or no extra capital.

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34

Majumdar, Krishna C. y Gour H. Jana. "Article". Canadian Journal of Chemistry 76, n.º 3 (1 de marzo de 1998): 297–300. http://dx.doi.org/10.1139/v98-017.

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A number of allyl aryl propargyl amines 3a-3f were synthesized in 68-82% yield. These tertiary amines were then treated with one equivalent of m-chloroperoxybenzoic acid (m-CPBA) to give products 5a-5f in 79-90% yields arising out of the Meisenheimer rearrangement of the allyl aryl amine moiety accompanying the amine oxide rearrangement of the aryl propargyl amine moiety.Key words: Meisenheimer rearrangement, [2,3] sigmatropic shift, amine oxide, propargyl amine, allyl amine.

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35

You, Y., V. P. Kanawade, J. A. de Gouw, A. B. Guenther, S. Madronich, M. R. Sierra-Hernández, M. Lawler et al. "Atmospheric amines and ammonia measured with a Chemical Ionization Mass Spectrometer (CIMS)". Atmospheric Chemistry and Physics Discussions 14, n.º 11 (20 de junio de 2014): 16411–50. http://dx.doi.org/10.5194/acpd-14-16411-2014.

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Abstract. We report ambient measurements of amines and ammonia with a~fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest in Alabama and a~moderately polluted Midwestern site during the summer. In the Alabama forest, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected on a daily basis. C3-amines and ammonia showed similar diurnal trends and temperature and wind direction dependences, and were not associated with transported CO and SO2 plumes. Consistent with temperature dependences, amine and ammonia in the gas and aerosol phases showed opposite diurnal trends, indicating gas-to-particle partitioning of amines and ammonia. Temperature dependences also imply reversible processes of amines and ammonia evaporation from soil surfaces in daytime and deposition of amines and ammonia to soil surfaces at nighttime. Various amines (C1–C6) at the pptv level were observed in the transported biomass burning plumes, showing that biomass burning can be a substantial source of amines in the Southeast US. At the moderately polluted Kent site, higher concentrations of amines (C1–C6, from pptv to tens of pptv) and ammonia (up to 6 ppbv) were detected. Diurnal variations of C1- to C3-amines and ammonia were correlated with the ambient temperature. C4- to C6-amines showed abrupt increases during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Lower amine concentrations at the rural forested site highlight the importance of constraining anthropogenic sources of amines.

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36

Biswas, Supriya, Mahammad Ali, Zvi Rappoport y Hatim Salim. "Reactions of α-isobutyl-α-(methylthio)methylene Meldrum's acid with primary amines in aqueous DMSO". Canadian Journal of Chemistry 84, n.º 12 (1 de diciembre de 2006): 1679–85. http://dx.doi.org/10.1139/v06-166.

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The aminolysis of α-isobutyl-α-(methylthio)methylene Meldrum's acid 7 with primary amines, namely, n-butylamine, glycinamide, and methoxyethylamine in DMSO–H2O (50:50, v/v) at 20 °C is overall second-order but first-order in both 7 and amines. The reaction with aminoacetonitrile (AA) is overall third-order, first-order in substrate, and second-order in amine at low amine concentration, while at high amine concentration and high pH the dependence on amine is first-order. A general three-step mechanism has been proposed for all these reactions. For the former group of amines, the first step is a rate-limiting attack of the amine to form the tetrahedral intermediate (TA±), followed by a fast acid–base equilibrium and a fast RNH3+- or H2O-assisted leaving group expulsion. For AA, general base catalysis was confirmed from the dependence of kA on [AA]f and on [OH–]. For all four amines, a good Brønsted plot of log k1 vs. pKaAH in DMSO–H2O (50:50, v/v) with βnuc = 0.34 ± 0.02 was observed. These observations are consistent with the suggested mechanism.Key words: nucleophilic vinylic substitution reactions, primary amines, α-isobutyl-α-(methylthio)methylene Meldrum's acid, three-step mechanism.

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37

Šindelář, Karel, Josef Pomykáček, Martin Valchář, Karel Dobrovský, Jiřina Metyšová y Zdeněk Polívka. "Potential antidepressants and inhibitors of 5-hydroxytryptamine and noradrenaline re-uptake in the brain: N,N-Dimethyl-(arylthio)thenylamines and N,N-dimethyl-2-(thienylthio)benzylamines". Collection of Czechoslovak Chemical Communications 56, n.º 2 (1991): 449–58. http://dx.doi.org/10.1135/cccc19910449.

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3-(3-Methoxyphenylthio)thiophene-2-carboxylic acid (IV) and 2-(3-methoxyphenylthio)thiophene-3-carboxylic acid (VII) were transformed via acid chlorides and dimethylamides to the amines V and VIII which were demethylated to the phenolic amines VI and IX. N,N-Dimethyl-4-bromothiophene-3-carboxamide (XI) was reacted with 3-methoxythiophenol and the amide XII was reduced and demethylated to the amine XIV. 2-(2-Thienylthio)benzoic acid (XVa) and 2-(5-bromo-2-thienylthio)benzoic acid (XVb) were transformed via the isolated acid chlorides and N,N-dimethylamides to the amines XVIIIa and XVIIIb. The amines VI, IX, and XIV are thiophene isosters of moxifetin, the potent inhibitor of 5-hydroxytryptamine re-uptake in the brain structures. Out of the compounds prepared, only the methoxy amine VIII (VUFB-17697) showed a similar type of activity. The intermediate V, the phenolic amine VI, and the hydroxyl group lacking amine XVIIIa are selective inhibitors of noradrenaline re-uptake in the brain.

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38

Vinci, Giuliana y Lucia Maddaloni. "Biogenic Amines in Alcohol-Free Beverages". Beverages 6, n.º 1 (9 de marzo de 2020): 17. http://dx.doi.org/10.3390/beverages6010017.

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Biogenic amines are ubiquitous bioactive compounds that are synthesized by living organisms and perform essential functions for their metabolism. In the human diet, their excessive intake can cause food poisoning. In food, especially in alcohol-free beverages, biogenic amines can be synthesized by enzymes, naturally present in raw materials, or by microorganisms, which may be naturally present in the matrix or be added during beverage transformation processes. For this reason, in alcohol-free beverages, biogenic amine amount can be considered, above a certain level, as undesired microorganism activity. Therefore, it is important to evaluate the biogenic amine profile of non-alcoholic beverages in order to monitor food quality and safety. Moreover, biogenic amines can be taken into account by industries in order to monitor production processes and products. This review article provides an overview on the biogenic amine profile of alcohol-free beverages (plant milk, nervine drinks, soft drinks, and fruit juices). Furthermore, the clinical and toxicological effects, the biogenic amines legislation, and biogenic amine synthesis have been evaluated in non-alcoholic beverages.

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39

Van Os, M., B. Lassalas, S. Toillon y J. P. Jouany. "In vitrodegradation of amines by rumen micro-organisms". Journal of Agricultural Science 125, n.º 2 (octubre de 1995): 299–305. http://dx.doi.org/10.1017/s0021859600084446.

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SUMMARYDegradation of biogenic amines was studied in rumen contents obtained from wether sheep adapted to diets with different levels of biogenic amines: high (H), low (L) and without (W), containing 7·4, 2·4 and 0 g amines/kg dry matter (DM), respectively. To 200 g of the rumen contents (RC), 2 ml of a solution containing a mixture of the biogenic amines: cadaverine (73·5 mmol/1), histamine (45·0 mmol/1), putrescine (830 mmol/1) and tyramine (123·5 mmol/1) were added, followed by a 5 h incubationin vitro. The fermentation pattern in RC derived from H and L differed from that in RC derived from W. This difference was attributed to differences in fermentative properties of silage and hay-based diets in the rumen. The addition of amines increased ammonia production, which was highest in RC from sheep adapted to silage with the highest amine content (diet H). Amines had no influence on gas production. Amine degradation occurred in all types of RC, but the extent depended on adaptation of the rumen microflora, such that 709, 54·2 and 25·3% of the added quantity in RC from H, L and W, respectively, was degraded. Generally, the breakdown of the individual amines was highest for histamine, followed by tyramine, putrescine and cadaverine. Tyramine breakdown was particularly slow in RC from diet W. These results imply that in animals adapted to grass silage with high concentrations of biogenic amines, the accumulation of amines in the rumen will be prevented by an increase in the amine-degrading capacity of the rumen microbes.

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40

Chong, Nyuk-Min. "BIOLOGICAL TREATABILITY OF AMINE LADEN REFINERY WASTEWATER". Water Science and Technology 30, n.º 3 (1 de agosto de 1994): 21–28. http://dx.doi.org/10.2166/wst.1994.0054.

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Mono- and Di- hydroxyl amines are used in the desulfuration processes for refined petroleum products. The refinery wastewater treatment plant may be shocked by amine laden wastewater periodically, bringing operation difficulties to the biological treatment units. Data on the treatability, shock load behaviour and on long term system stability of biological treatment of amines are therefore required. Shake-flask test results showed that pure diethanol amine and diisopropanol amines have characteristics of persistent compounds. Each of the two compounds has a prolonged lag time when first inoculated with indigenous activated sludge. Acclimated activated sludge in a continuous flow reactor treated a feed of ethanol amine with a 93 percent COD removal and a 98 percent nitrification, but the system was unstable because amine caused a bulking sludge. By physical retention of the activated sludge, 550 mg/l influent COD of amines was treated to m1 average 50 mg/l effluent COD. Sludge yield was approximately 0.26 mg MLSS per mg COD. The activated sludge system withstood a chm1ge of feed to a real refinery wastewater laden with the; amine. A mean cell residence time above five (5) days should be maintained for safe treatment of; amine.

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41

You, Y., V. P. Kanawade, J. A. de Gouw, A. B. Guenther, S. Madronich, M. R. Sierra-Hernández, M. Lawler et al. "Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)". Atmospheric Chemistry and Physics 14, n.º 22 (19 de noviembre de 2014): 12181–94. http://dx.doi.org/10.5194/acp-14-12181-2014.

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Abstract. We report measurements of ambient amines and ammonia with a fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest and a moderately polluted midwestern site during the summer. At the forest site, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected, and they both showed temperature dependencies. Aerosol-phase amines measured thermal-desorption chemical ionization mass spectrometer (TDCIMS) showed a higher mass fraction in the evening with cooler temperatures and lower in the afternoon with warmer temperatures, a trend opposite to the gas-phase amines. Concentrations of aerosol-phase primary amines measured with Fourier transform infrared spectroscopy (FTIR) from micron and submicron particles were 2 orders of magnitude higher than the gas-phase amines. These results indicate that gas to particle conversion is one of the major processes that control the ambient amine concentrations at this forest site. Temperature dependencies of C3-amines and ammonia also imply reversible processes of evaporation of these nitrogen-containing compounds from soil surfaces in daytime and deposition to soil surfaces at nighttime. During the transported biomass burning plume events, various amines (C1–C6) appeared at the pptv level, indicating that biomass burning is a substantial source of amines in the southeastern US. At the moderately polluted Kent site, there were higher concentrations of C1- to C6-amines (pptv to tens of pptv) and ammonia (up to 6 ppbv). C1- to C3-amines and ammonia were well correlated with the ambient temperature. C4- to C6-amines showed frequent spikes during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Higher amine concentrations measured at the polluted site than at the rural forested site highlight the importance of constraining anthropogenic emission sources of amines.

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42

Hamana, K., M. Niitsu, S. Matsuzaki, K. Samejima, Y. Igarashi y T. Kodama. "Novel linear and branched polyamines in the extremely thermophilic eubacteria Thermoleophilum, Bacillus and Hydrogenobacter". Biochemical Journal 284, n.º 3 (15 de junio de 1992): 741–47. http://dx.doi.org/10.1042/bj2840741.

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Novel tertiary branched tetra-amines, quaternary branched penta-amines, linear penta-amines and linear hexa-amines were distributed as the major polyamines in six obligately extremely thermophilic eubacteria belonging to Thermoleophilum, Bacillus or Hydrogenobacter. The major polyamine of Thermoleophilum album and Thermoleophilum minutum was identified as a quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N+([CH2]3NH2)2[CH2]4NH2) by h.p.l.c., t.l.c. and g.c.-m.s. Hydrogenobacter thermophilus and Hydrogenobacter halophilus contained another quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)2[CH2]3NH2) as the major polyamine, and tertiary branched tetra-amines (4-(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)[CH2]3NH2), 4-(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N([CH2]3NH2)[CH2]4NH2)) and 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane were confirmed as minor components. Bacillus schlegelii contained a branched tetra-amine, 4-(3-aminopropyl)-1,8-diamino-4-azaoctane, a branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane, a linear penta-amine, 1,16-diamino-4,8,13-triazahexadecane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2) and linear hexa-amine(s), 1,20-diamino-4,8,12,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2) and/or 1,20-diamino-4,8,13,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH[CH2]3NH2).

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43

Berman, Edward D., Rosemarie Thomas, Philip Stahl y Ronald M. Scott. "Specific patterns of short range solvation — aliphatic amines in benzene–dimethylsulfoxide mixed solvents". Canadian Journal of Chemistry 65, n.º 7 (1 de julio de 1987): 1594–98. http://dx.doi.org/10.1139/v87-267.

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The trends in the values of equilibrium constants for the formation of proton transfer complexes between 2,4-dinitrophenol and various aliphatic amines are used to infer the nature of the short range solvation of the amines in benzene–DMSO solvent mixtures. Hydrogen bonds between the DMSO oxygen and the amine proton increase the basicity of the primary and secondary amines. Equilibrium constants for this bond formation are estimated for secondary amines.

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44

Souza, Solange C., Karine H. Theodoro, Élson R. Souza, Silvana da Motta y Maria Beatriz Abreu Glória. "Bioactive amines in Brazilian wines: types, levels and correlation with physico-chemical parameters". Brazilian Archives of Biology and Technology 48, n.º 1 (enero de 2005): 53–62. http://dx.doi.org/10.1590/s1516-89132005000100009.

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The levels of ten bioactive amines and the physico-chemical characteristics of Cabernet Sauvignon, Cabernet Franc and Merlot wines from Bento Gonçalves, RS, Brazil, vintage of 1999 were investigated. The physico-chemical characteristics varied significantly: pH from 3.80 to 4.07, total acidity from 67.7 to 85.3 meq/L, alcohol content from 11.45 to 12.46 mL/100 mL and total SO2 from 9.6 to 102 mg/L. Six amines were detected in every sample - spermidine, putrescine, histamine, tyramine, serotonine and phenylethylamine. Total amine levels ranged from 2.03 to 7.60 mg/L. Putrescine was the prevalent amine, contributing with 20 to 66% of total levels. The amine profile and total levels were affected to a greater extent by vinification practices compared to grape type. There was significant correlation between some amines and also between amines and the physico-chemical parameters. Histamine levels were well below limits recommended by several countries.

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45

Kutschy, Peter, Pavol Kristian, Milan Dzurilla, Dušan Koščík y Róbert Nádaskay. "Selectivity of nucleophilic addition to and substitution at isothiocyanatocarbonyl group. Reactions of 4-pentinoyl- and 2-(2-propinyl)-4-pentinoyl isothiocyanate with amines and methanol". Collection of Czechoslovak Chemical Communications 52, n.º 4 (1987): 995–1005. http://dx.doi.org/10.1135/cccc19870995.

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4-Pentinoyl isothiocyanate reacts with primary and secondary amines by either nucleophilic addition to N=C=S group to yield the corresponding thioureas, or a nucleophilic substitution at the carbonyl group to give 4-pentinoic acid amides. The less nucleophilic diphenylamine reacts selectively to afford the product of nucleophilic addition only. 2-(2-Propinyl)-4-pentinoyl isothiocyanate, having a sterically hindered carbonyl group, furnished with primary amines a mixture of amides and thioureas, whereas the bulkier secondary amines react selectively to form thioureas only. Both isothiocyanates afford with methanol as a nucleophile exclusively the corresponding O-methyl monothiocarbamates.

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46

Li, Bin, Jean-Baptiste Sortais y Christophe Darcel. "Amine synthesis via transition metal homogeneous catalysed hydrosilylation". RSC Advances 6, n.º 62 (2016): 57603–25. http://dx.doi.org/10.1039/c6ra10494k.

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This review summarizes the preparation of amines involving homogeneous transition metal catalysed hydrosilylation including reductions of imines, amides, nitro and nitriles, reductive aminations and N-methylation of amines with CO₂.

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47

Khalimon, Andrey, Kristina Gudun y Davit Hayrapetyan. "Base Metal Catalysts for Deoxygenative Reduction of Amides to Amines". Catalysts 9, n.º 6 (28 de mayo de 2019): 490. http://dx.doi.org/10.3390/catal9060490.

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The development of efficient methodologies for production of amines attracts significant attention from synthetic chemists, because amines serve as essential building blocks in the synthesis of many pharmaceuticals, natural products, and agrochemicals. In this regard, deoxygenative reduction of amides to amines by means of transition-metal-catalyzed hydrogenation, hydrosilylation, and hydroboration reactions represents an attractive alternative to conventional wasteful techniques based on stoichiometric reductions of the corresponding amides and imines, and reductive amination of aldehydes with metal hydride reagents. The relatively low electrophilicity of the amide carbonyl group makes this transformation more challenging compared to reduction of other carbonyl compounds, and the majority of the reported catalytic systems employ precious metals such as platinum, rhodium, iridium, and ruthenium. Despite the application of more abundant and environmentally benign base metal (Mn, Fe, Co, and Ni) complexes for deoxygenative reduction of amides have been developed to a lesser extent, such catalytic systems are of great importance. This review is focused on the current achievements in the base-metal-catalyzed deoxygenative hydrogenation, hydrosilylation, and hydroboration of amides to amines. Special attention is paid to the design of base metal catalysts and the mechanisms of such catalytic transformations.

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Zarecki, Adam P., Jacek L. Kolanowski y Wojciech T. Markiewicz. "Microwave-Assisted Catalytic Method for a Green Synthesis of Amides Directly from Amines and Carboxylic Acids". Molecules 25, n.º 8 (11 de abril de 2020): 1761. http://dx.doi.org/10.3390/molecules25081761.

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Amide bonds are among the most interesting and abundant molecules of life and products of the chemical pharmaceutical industry. In this work, we describe a method of the direct synthesis of amides from carboxylic acids and amines under solvent-free conditions using minute quantities of ceric ammonium nitrate (CAN) as a catalyst. The reactions are carried out in an open microwave reactor and allow the corresponding amides to be obtained in a fast and effective manner when compared to other procedures of the direct synthesis of amides from acids and amines reported so far in the literature. The amide product isolation procedure is simple, environmentally friendly, and is performed with no need for chromatographic purification of secondary amides due to high yields. In this report, primary amines were used in most examples. However, the developed procedure seems to be applicable for secondary amines as well. The methodology produces a limited amount of wastes, and a catalyst can be easily separated. This highly efficient, robust, rapid, solvent-free, and additional reagent-free method provides a major advancement in the development of an ideal green protocol for amide bond formation.

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49

ORDÓÑEZ, ANA I., FRANCISCO C. IBÁÑEZ, PALOMA TORRE y YOLANDA BARCINA. "Formation of Biogenic Amines in Idiazábal Ewe's-Milk Cheese: Effect of Ripening, Pasteurization, and Starter". Journal of Food Protection 60, n.º 11 (1 de noviembre de 1997): 1371–75. http://dx.doi.org/10.4315/0362-028x-60.11.1371.

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The importance of biogenic amines stems from their toxicity and their potential as a cause of food poisoning. After fish, cheese has been the foodstuff most often responsible for cases of food poisoning caused by ingestion of biogenic amines. Changes in biogenic amine (histamine, tyramine, putrescine, cadaverine, tryptamine, isopentylamine, spermidine, and phenylethylamine) content during the ripening of a cheese made from raw ewe's milk were studied, together with the effects of pasteurization and a commonly used commercial starter and indigenous starter cultures. Biogenic amines were determined by high-pressure liquid chromatography following extraction from the cheese and derivatization with dansyl chloride. Levels of histamine, potentially the most toxic amine, in the semihard Idiazábal cheese were very low. Tyramine, putrescine, and cadaverine were the main amines present in this type of cheese. Levels of those amines increased during ripening. Pasteurization of the milk brought about a reduction in the biogenic amine content of the ripened cheese, irrespective of the starter culture employed. The indigenous starter cultures considered in this study produced higher levels of histamine and cadaverine and lower levels of tyramine and putrescine than the commercial starter culture tested.

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50

González-Martínez, Daniel, Nerea Fernández-Sáez, Carlos Cativiela, Joaquín Campos y Vicente Gotor-Fernández. "Development of Biotransamination Reactions towards the 3,4-Dihydro-2H-1,5-benzoxathiepin-3-amine Enantiomers". Catalysts 8, n.º 10 (19 de octubre de 2018): 470. http://dx.doi.org/10.3390/catal8100470.

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The stereoselective synthesis of chiral amines is an appealing task nowadays. In this context, biocatalysis plays a crucial role due to the straightforward conversion of prochiral and racemic ketones into enantiopure amines by means of a series of enzyme classes such as amine dehydrogenases, imine reductases, reductive aminases and amine transaminases. In particular, the stereoselective synthesis of 1,5-benzoxathiepin-3-amines have attracted particular attention since they possess remarkable biological profiles; however, their access through biocatalytic methods is unexplored. Amine transaminases are applied herein in the biotransamination of 3,4-dihydro-2H-1,5-benzoxathiepin-3-one, finding suitable enzymes for accessing both target amine enantiomers in high conversion and enantiomeric excess values. Biotransamination experiments have been analysed, trying to optimise the reaction conditions in terms of enzyme loading, temperature and reaction times.

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Artículos de revistas sobre el tema "Amines"

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