Статті в журналах: "Dioll"

1

Grobelny, Zbigniew, Justyna Jurek-Suliga, and Sylwia Golba. "Application of Monopotassium Dipropylene Glycoxide for Homopolymerization and Copolymerization of Monosubstituted Oxiranes: Characterization of Synthesized Macrodiols by MALDI-TOF Mass Spectrometry." Polymers 12, no. 12 (November 26, 2020): 2795. http://dx.doi.org/10.3390/polym12122795.

Повний текст джерела

Анотація:

Monopotassium dipropylene glycoxide, activated by a 18-crown-6 cation complexing agent (K-DPG/L, where DPG (dipropylene glycol) is a mixture of isomers) was used as an effective initiator of the homopolymerization and copolymerization of several monosubstituted oxiranes, i.e., propylene oxide (PO), 1.2-butylene oxide (BO), and some glycidyl ethers such as allyl, isopropyl, phenyl, and benzyl ones (AGE, IPGE, PGE, and BGE, respectively). The copolymers are novel and can be prospectively used for the fabrication of new thermoplastic or crosslinked polyurethanes. All processes were carried out in homogeneous mild conditions, i.e., tetrahydrofuran solution at room temperature and normal pressure. They resulted in new unimodal macrodiols with Mn = Mcalc in the range of 1500–8300, low dispersity Mw/Mn = 1.08–1.18 and a chemical structure well defined by several techniques, i.e., MALDI-TOF, size exclusion chromatography (SEC), 13C NMR, and FTIR. Monopotassium salts of homopolyether-diols, i.e., PPO-diol, PBO-diol, and PAGE-diol, appeared to be useful macroinitiators for the preparation of new triblock copolyether-diols by polymerization of glycidyl ethers. In BO/BGE random copolymerization initiated with K-DPG/L, macromolecules of copolyether-diol were exclusively formed. Macromolecules of copolyether-diol accompanied by homopolyether PPO-diol were identified in the PO/PGE system. However, AGE and PGE reacted by giving random copolyether-diol as well as homopolymer-diols, i.e., PAGE-diol and PPGE-diol. Macromolecules of prepared copolyether-diols contain various numbers of mers deriving from comonomers; the kind of comonomer determines the composition of the product. Several prepared homopolyether-diols and copolyether-diols could be useful for the synthesis of new thermoplastic polyurethanes.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Wu, Tong, Yumei Liu, Jinsheng Liu, Zhenya Chen, and Yi-Xin Huo. "Metabolic Engineering and Regulation of Diol Biosynthesis from Renewable Biomass in Escherichia coli." Biomolecules 12, no. 5 (May 18, 2022): 715. http://dx.doi.org/10.3390/biom12050715.

Повний текст джерела

Анотація:

As bulk chemicals, diols have wide applications in many fields, such as clothing, biofuels, food, surfactant and cosmetics. The traditional chemical synthesis of diols consumes numerous non-renewable energy resources and leads to environmental pollution. Green biosynthesis has emerged as an alternative method to produce diols. Escherichia coli as an ideal microbial factory has been engineered to biosynthesize diols from carbon sources. Here, we comprehensively summarized the biosynthetic pathways of diols from renewable biomass in E. coli and discussed the metabolic-engineering strategies that could enhance the production of diols, including the optimization of biosynthetic pathways, improvement of cofactor supplementation, and reprogramming of the metabolic network. We then investigated the dynamic regulation by multiple control modules to balance the growth and production, so as to direct carbon sources for diol production. Finally, we proposed the challenges in the diol-biosynthesis process and suggested some potential methods to improve the diol-producing ability of the host.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Vaughan, GT, and BV Milborrow. "The Occurrence and Metabolism of the 1',4'-Diols of Abscisic Acid." Functional Plant Biology 14, no. 5 (1987): 593. http://dx.doi.org/10.1071/pp9870593.

Повний текст джерела

Анотація:

The 1',4'-cis- and the 1',4'-trans-diols of abscisic acid (ABA) were produced when R,S-[2-14C]ABA was supplied to avocado fruit and broad bean shoots. The trans-diol was also a metabolite of R,S-ABA in peas but not in tomatoes. The diols were derived from both R- and S-ABA with the R- enantiomer predominating. The 1',4'-cis- and 1',4'-trans-diol were found to be endogenous constituents of avocado (14.5 ng/g and 93 ng/g respectively) and the trans-diol was found in pea shoots (5.2 ng/g). At low concentrations, exogenous 1',4'-cis- and 1',4'-trans-diols were metabolised by tomatoes, mainly to dihydrophaseic acid-4'-O-β-D-glucopyranoside. As the concentrations of the diols supplied to tomato shoots increased, a greater proportion was conjugated to form their 4'-glucosides and glucose esters. When the 1',4'-[2-14C, 4'-2H]trans-diol of ABA was supplied to tomato shoots the deuterium atom was lost from the 4'- position during conversion into the 4'-glucoside of DPA. This suggests that the trans-diol is converted into DPA via enzymic oxidation to ABA.

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Versteegh, Gerard J. M., Karin A. F. Zonneveld, Jens Hefter, Oscar E. Romero, Gerhard Fischer, and Gesine Mollenhauer. "Performance of temperature and productivity proxies based on long-chain alkane-1, mid-chain diols at test: a 5-year sediment trap record from the Mauritanian upwelling." Biogeosciences 19, no. 5 (March 18, 2022): 1587–610. http://dx.doi.org/10.5194/bg-19-1587-2022.

Повний текст джерела

Анотація:

Abstract. Proxies based on long-chain alkane-1, mid-chain diols (diol for short) are obtaining increasing interest to reconstruct past upper ocean temperature and productivity. Here we evaluate performance of the sea surface temperature proxies (long-chain diol index (LDI), diol saturation index (DSI), and diol chain length index (DCI)), productivity and upwelling intensity proxies (two diol indices DIR and DIW and the combined diol index (CDI)), and the nutrient diol index (NDI) as a proxy for phosphate and nitrate levels. This evaluation is based on comparison of the diols in sediment trap samples from the upwelling region off NW Africa collected at 1.28 km water depth with daily satellite-derived sea surface temperatures (SSTs), subsurface temperatures, productivity, the plankton composition from the trap location, monthly phosphate and nitrate concentrations, wind speed, and wind direction from the nearby Nouadhibou airport. The diol-based SST reconstructions are also compared the long-chain-alkenone-based SST reconstructions. The alkenone SSTs correlate best with satellite SST (r2= 0.60). Amplitude and absolute values agree very well as do the flux-corrected time series averages. For the diol proxies the situation is more complicated. Diol proxies including 1,14 diols lag trade wind speed by 30 d. Since wind is nearly always from the NNE to NNW and induces the upwelling, we relate the variability in these proxies to upwelling-induced processes. Correlation with the abundance of upwelling species and wind speed is best for the NDI and the 1,14 diol-based DCI and DSI. The DIR, DIW, and CDI perform comparatively poorly. A negative correlation between DSI and wind speed may suggest that the DSI reflects wind-speed-forced upwelling-related reductions in temperature rather than irradiation-induced temperatures. The nutrient proxy NDI shows no significant correlation to monthly phosphate and nitrate concentrations in the upper waters and a negative correlation with both wind-induced upwelling (r2=0.28 and lagging 32 d) and the abundance of upwelling species (r2=0.38). It is suggested that this proxy reflects upwelling intensity rather than upper ocean nutrient concentrations. At the trap site, satellite SST lags wind-speed-forced upwelling by about 4 months. The 1,13 and 1,15 diol-based LDI-derived SSTs lag satellite SSTs by 41 d but correlate poorly (r2= 0.17). Absolute as well as flux-corrected LDI SSTs are on average 3 ∘C too high and rather reflect values prevailing during the more oligotrophic summer period. We attribute outliers to low LDI SST to 1,13 diols added during short upwelling-related events. The use of the LDI in regions with higher productivity is therefore not recommended. It appears thus that at the trap site the 1,14 diols primarily reflect conditions relating to upwelling whereas the 1,15C30 and to a lesser extent the 1,13 diols seem to reflect the conditions of the more oligotrophic ocean.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Pérez-Palacios, Gregorio, René Santillán, Rocío García-Becerra, Elizabeth Borja-Cacho, Fernando Larrea, Pablo Damián-Matsumura, Leticia González, and Ana E. Lemus. "Enhanced formation of non-phenolic androgen metabolites with intrinsic oestrogen-like gene transactivation potency in human breast cancer cells: a distinctive metabolic pattern." Journal of Endocrinology 190, no. 3 (September 2006): 805–18. http://dx.doi.org/10.1677/joe.1.06407.

Повний текст джерела

Анотація:

Breast cancer is a sex steroid hormone-dependent malignant neoplasia. The role of oestradiol in this malignancy has been well documented; however, the involvement of androgens has remained controversial. To determine the role of non-phenolic androgen metabolites in human breast cancer, we studied the metabolism of [14C] testosterone and [14C] androstenedione in oestrogen-dependent MCF-7 cells and non-oestrogen-dependent MDA-MB 231 cells, at different substrate concentrations (1–10 μM) and time periods (30 min–48 h). Cultured non-oestrogen-dependent HeLa and yeast cells served as controls. Metabolites were identified and quantified by reverse isotope dilution. A distinctive pattern of androgen metabolism was identified in MCF-7 cells, being the 5α-androstane-3α,17β-diol (3α,5α-diol) and its 3β epimer (3β,5α-diol), the major conversion products of testosterone (48.3%), with 5α-dihydrotestosterone as intermediary. The formation of 3α,5α-diol and 3β,5α-diol (diols) was substrate concentration- and time-dependent, and abolished by finasteride. In contrast, very little of any diol formation was observed in MDA-MB 231, HeLa and yeast cell incubations. Additional enzyme gene expression studies revealed an overexpression of 5α-steroid reductase type-1 in MCF-7 cells, as compared with MDA-MB 231 cells. The oestrogen-like activities of diols were assessed in HeLa cells co-transfected with expression vectors for α or β subtypes of the human oestrogen receptor (hER) genes and for an oestrogen-responsive reporter gene. The results show that 3β, 5α-diol and to a lesser extent 3α,5α-diol bind with high relative affinity to hERα and hERβ. Both diols induced hER-mediated reporter gene transactivation in a dose–response manner, similar to that induced by oestradiol, though with lower potency, an effect that was abolished by ICI-182 780. Furthermore, 3β,5α-diol and to lesser extent 3α,5α-diol induced MCF-7 cell proliferation. The overall results demonstrated that MCF-7 cells exhibit enhanced expression and activity of androgen-metabolising enzymes, leading to rapid and large diol formation, and provide evidence that these androgen metabolites exert a potent oestrogen-agonistic effect, at genomic level, in oestrogen-dependent breast cancer cells. The data suggest that diols may act as in situ intracrine factors in breast cancer and that its formation can be pharmacologically inhibited.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Friestad, Gregory K., and Gopeekrishnan Sreenilayam. "1,5-Polyols: Challenging motifs for configurational assignment and synthesis." Pure and Applied Chemistry 83, no. 3 (January 31, 2011): 461–78. http://dx.doi.org/10.1351/pac-con-10-10-19.

Повний текст джерела

Анотація:

Despite the well-established methods for stereochemical assignments and synthesis of 1,3-diols, the corresponding 1,5-diols and -polyols present specific challenges which remain unsolved. This article highlights some new strategies and methodologies specifically designed for the 1,5-diol motif.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Namkajorn, M., Atitsa Petchsuk, Mantana Opaprakasit, and Pakorn Opaprakasit. "Synthesis and Characterization of PLA-Based Aliphatic-Aromatic Copolyesters: Effect of Diols." Advanced Materials Research 55-57 (August 2008): 785–88. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.785.

Повний текст джерела

Анотація:

PLA-based aliphatic aromatic copolyesters have been synthesized and characterized in order to incorporate the degradability of PLA and good mechanical properties of aromatic species. Synthesis of the copolymers was conducted by polycondensation of lactic acid with dimethyl terephthalate (DMT) and various diols using stannous(II) octoate as a catalyst. Three types of diols with different methylene lengths were employed, i.e., ethylene glycol (EG), propylene glycol (PG) and 1, 4-butanediol (BD). Effects of diols and comonomer molar ratio on the extent of polycondensation reaction and molecular weight of the resulting copolymers were investigated. Diacids and diol ratios of L-lactic acid (LLA), dimethyl terephthalate (DMT) and diol of 1/1/2, 1/2/4 and 2/1/2 were employed. Characterization of chemical structure, molecular weight and thermal and physical properties of the resulting copolymers were conducted by FTIR, NMR, and DSC.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Balzano, Sergio, Julie Lattaud, Laura Villanueva, Sebastiaan W. Rampen, Corina P. D. Brussaard, Judith van Bleijswijk, Nicole Bale, Jaap S. Sinninghe Damsté, and Stefan Schouten. "A quest for the biological sources of long chain alkyl diols in the western tropical North Atlantic Ocean." Biogeosciences 15, no. 19 (October 10, 2018): 5951–68. http://dx.doi.org/10.5194/bg-15-5951-2018.

Повний текст джерела

Анотація:

Abstract. Long chain alkyl diols (LCDs) are widespread in the marine water column and sediments, but their biological sources are mostly unknown. Here we combine lipid analyses with 18S rRNA gene amplicon sequencing on suspended particulate matter (SPM) collected in the photic zone of the western tropical North Atlantic Ocean at 24 stations to infer relationships between LCDs and potential LCD producers. The C30 1,15-diol was detected in all SPM samples and accounted for >95 % of the total LCDs, while minor proportions of C28 and C30 1,13-diols, C28 and C30 1,14-diols, as well as C32 1,15-diol were found. The concentration of the C30 and C32 diols was higher in the mixed layer of the water column compared to the deep chlorophyll maximum (DCM), whereas concentrations of C28 diols were comparable. Sequencing analyses revealed extremely low contributions (≈0.1 % of the 18S rRNA gene reads) of known LCD producers, but the contributions from two taxonomic classes with which known producers are affiliated, i.e. Dictyochophyceae and Chrysophyceae, followed a trend similar to that of the concentrations of C30 and C32 diols. Statistical analyses indicated that the abundance of 4 operational taxonomic units (OTUs) of the Chrysophyceae and Dictyochophyceae, along with 23 OTUs falling into other phylogenetic groups, were weakly (r≤0.6) but significantly (p value <0.01) correlated with C30 diol concentrations. It is not clear whether some of these OTUs might indeed correspond to C28−32 diol producers or whether these correlations are just indirect and the occurrence of C30 diols and specific OTUs in the same samples might be driven by other environmental conditions. Moreover, primer mismatches were unlikely, but cannot be excluded, and the variable number of rRNA gene copies within eukaryotes might have affected the analyses leading to LCD producers being undetected or undersampled. Furthermore, based on the average LCD content measured in cultivated LCD-producing algae, the detected concentrations of LCDs in SPM are too high to be explained by the abundances of the suspected LCD-producing OTUs. This is likely explained by the slower degradation of LCDs compared to DNA in the oxic water column and suggests that some of the LCDs found here were likely to be associated with suspended debris, while the DNA from the related LCD producers had been already fully degraded. This suggests that care should be taken in constraining biological sources of relatively stable biomarker lipids by quantitative comparisons of DNA and lipid abundances.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Sui, Jinkai, Chunkai Wang, Xiaofeng Liu, Ning Fang, Yanhua Liu, Wenjing Wang, Ning Yan та ін. "Formation of α- and β-Cembratriene-Diols in Tobacco (Nicotiana tabacum L.) Is Regulated by Jasmonate-Signaling Components via Manipulating Multiple Cembranoid Synthetic Genes". Molecules 23, № 10 (30 вересня 2018): 2511. http://dx.doi.org/10.3390/molecules23102511.

Повний текст джерела

Анотація:

Cembranoids are a group of natural diterpenoid compounds with pharmaceutical potentials, and the cembratriene-diols produced by Nicotiana (tobacco) species display activities in anti-nicotine addiction and neuron protection. Although the enzymes catalyzing cembratriene-diols’ formation in tobacco have been investigated, the regulatory mechanism underlying this physiological process remains unknown. This study has investigated the roles of phytohormone jasmonic acid (JA) in regulating cembratriene-diol formation in N. tabacum cv. TN90 and found that JA and COI1, the receptor protein of the bioactive derivative of JA (i.e., JA-Ile), display critical roles in regulating cembratriene-diols’ formation and the expression of cembranoid synthetic genes CBTS, P450 and NtLTP1. Further studies showed that over-expressing either the gene encoding bHLH transcription factor MYC2a or that encoding MYB transcription factor MYB305 could upregulate the cembranoid synthetic genes and enhance the cembranoid production in plants with dysfunction of COI1. Further studies suggest that COI1 and its downstream regulators MYC2a and MYB305 also modulate the trichome secretion, which is correlated with cembranoid formation. Taken together, this study has demonstrated a critical role of JA-signaling components in governing the cembratriene-diol formation and the transcription of cembratriene-diol synthetic genes in tobacco. Findings in this study are of great importance to reveal the molecular regulatory mechanism underlying cembranoid synthesis.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Wang, Jian, Chenyi Li, Yusong Zou, and Yajun Yan. "Bacterial synthesis of C3-C5 diols via extending amino acid catabolism." Proceedings of the National Academy of Sciences 117, no. 32 (July 27, 2020): 19159–67. http://dx.doi.org/10.1073/pnas.2003032117.

Повний текст джерела

Анотація:

Amino acids are naturally occurring and structurally diverse metabolites in biological system, whose potentials for chemical expansion, however, have not been fully explored. Here, we devise a metabolic platform capable of producing industrially important C3-C5 diols from amino acids. The presented platform combines the natural catabolism of charged amino acids with a catalytically efficient and thermodynamically favorable diol formation pathway, created by expanding the substrate scope of the carboxylic acid reductase toward noncognate ω-hydroxylic acids. Using the established platform as gateways, seven different diol-convertible amino acids are converted to diols including 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. Particularly, we afford to optimize the production of 1,4-butanediol and demonstrate the de novo production of 1,5-pentanediol from glucose, with titers reaching 1.41 and 0.97 g l−1, respectively. Our work presents a metabolic platform that enriches the pathway repertoire for nonnatural diols with feedstock flexibility to both sugar and protein hydrolysates.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Bończa-Tomaszewski, Zbigniew. "The potassium permanganate oxidation of steroidal homoannular dienes." Canadian Journal of Chemistry 65, no. 3 (March 1, 1987): 656–60. http://dx.doi.org/10.1139/v87-112.

Повний текст джерела

Анотація:

The oxidation of 3β-acetoxycholesta-5,7-diene (1) with potassium permanganate–sodium periodate reagent gave epoxy-diol 2 with almost quantitative yield. Similar oxidation of cholesta-2,4-diene (3) afforded, as well as epoxy-diols 5 and 6, products of cleavage of the double bonds. These results show that formation of epoxy-diols predominates in the case of hindered steroidal dienes (e.g., diene 1), whereas oxidation of unhindered steroidal dienes (e.g., diene 2) gives, in addition to epoxy-diols, products of cleavage of the double bonds.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Lv, Jian, Jian-Tao Ge, Tao Luo, and Hai Dong. "An inexpensive catalyst, Fe(acac)3, for regio/site-selective acylation of diols and carbohydrates containing a 1,2-cis-diol." Green Chemistry 20, no. 9 (2018): 1987–91. http://dx.doi.org/10.1039/c8gc00428e.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Matteson, Donald S. "New asymmetric syntheses with boronic esters and fluoroboranes." Pure and Applied Chemistry 75, no. 9 (January 1, 2003): 1249–53. http://dx.doi.org/10.1351/pac200375091249.

Повний текст джерела

Анотація:

Efficient cleavage of sterically hindered boronic esters of asymmetric diols to recover both the diol and a more reactive borane derivative has been a challenging problem. A remarkable borosilicate glass-catalyzed cleavage with thionyl chloride and imidazole proved less useful than hoped for. Potassium bifluoride converts boronic esters to diols and alkyltrifluoroborates. These with chlorosilanes yield alkyldifluoroboranes, which with alkyl azides form secondary amines in high enantiopurity.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Davis, BR, MG Hinds, and PPC Ting. "Clemmensen Reduction. X. The Synthesis and Acidolysis of Some Aryl Alkyl Substituted Cyclopropane-1,2-diols." Australian Journal of Chemistry 45, no. 5 (1992): 865. http://dx.doi.org/10.1071/ch9920865.

Повний текст джерела

Анотація:

The synthesis of a number of 1-alkyl-2-arylcyclopropane-1,2-diols is reported. Reductive treatment of suitably substituted 1,3-diketones gave a cyclopropanediyl diacetate from which the diol was obtained. Reaction of these diols with acid gave α- hydroxy ketones , in which an alkyl group, rather than an aryl group, was adjacent to the carbonyl function. Clemmensen reduction of the 1,3-diketones gave products of rearrangement, generally similar to those obtained by acidolysis of the cyclopropane-1,2-diols. The relationship of these results to thermochemical studies on the stability of carboxonium ions is discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Ferreira, Jeiely G., Cleverson R. Princival, Dyego M. Oliveira, Renata X. Nascimento, and Jefferson L. Princival. "Enzymatic kinetic resolution of internal propargylic diols. Part I: a new approach for the synthesis of (S)-pent-2-yn-1,4-diol, a natural product from Clitocybe catinus." Organic & Biomolecular Chemistry 13, no. 23 (2015): 6458–62. http://dx.doi.org/10.1039/c5ob00386e.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Hu, Keling, Dongping Zhao, Guolin Wu та Jianbiao Ma. "Synthesis and properties of polyesters derived from renewable eugenol and α,ω-diols via a continuous overheating method". Polymer Chemistry 6, № 40 (2015): 7138–48. http://dx.doi.org/10.1039/c5py01075f.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Reina, Robert J., Kevin D. White, and David Firestone. "Sterol and Triterpene Diol Contents of Vegetable Oils by High-Resolution Capillary Gas Chromatography." Journal of AOAC INTERNATIONAL 82, no. 4 (July 1, 1999): 929–35. http://dx.doi.org/10.1093/jaoac/82.4.929.

Повний текст джерела

Анотація:

Abstract An in-laboratory validated method for identification and quantitation of sterols and triterpene diols was used to determine the relative composition of identifiable sterols and triterpene diols in 13 vegetable oils and quantitate these components in multiple samples of 6 vegetable oils: extra virgin olive, pomace olive, corn, cottonseed, canola, and evening primrose oils. Erythrodiol, a triterpene diol present in all olive oils, was also found in cottonseed oil.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Sun, Yufeng, Yatao Huang, Minmin Li, Jia Lu, Nuo Jin, and Bei Fan. "Synthesis of cyclic ethers by cyclodehydration of 1, n -diols using heteropoly acids as catalysts." Royal Society Open Science 5, no. 9 (September 2018): 180740. http://dx.doi.org/10.1098/rsos.180740.

Повний текст джерела

Анотація:

Heteropoly acids were used as catalysts for cyclodehydration of various 1, n -diols. Cyclodehydration of butane-1,4-diol, pentane-1,5-diol and hexane-1,6-diol catalysed by H 3 PW 12 O 40 gave tetrahydrofuran, tetrahydropyran and oxepane, respectively. Cyclodehydration of diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether and polyethylene glycol 200 catalysed by H 3 PW 12 O 40 gave 1,4-dioxane. In particular, cyclodehydration of hexane-1,6-diol gave an excellent yield of oxepane (80%). The selectivity exhibited by the H 3 PW 12 O 40 catalyst was even better than that exhibited by other reported catalyst systems for similar cyclodehydration reactions.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Messerle, Barbara A., and Khuong Q. Vuong. "Synthesis of spiroketals by iridium-catalyzed double hydroalkoxylation." Pure and Applied Chemistry 78, no. 2 (January 1, 2006): 385–90. http://dx.doi.org/10.1351/pac200678020385.

Повний текст джерела

Анотація:

A highly efficient approach to the synthesis of spiroketals involves the double cyclization of alkynyl diols using transition-metal catalysts. The iridium complex [Ir(PyP)(CO)2]BPh4 where PyP = 1-[(2-diphenylphosphino)ethyl]pyrazole is an effective catalyst for promoting the formation of spiroketals via this double hydroalkoxylation reaction. The complex promotes the formation of a series of spiroketal products from alkynyl diol starting materials such as 3-ethynylpentane-1,5-diol and 2-(4-hydroxybut-1-ynyl)benzyl alcohol. Stereoselective cyclization occurs for 3-ethynylpentane-1,5-diol, 3-ethynylhexane-1,6-diol. The cycloadditions occur in all but one case with quantitative conversion in under 24 h at 120 °C.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Mallick, MAI, R. Bishop, DC Craig, IG Dance, and ML Scudder. "2,6-Dimethylbicyclo(3.3.1)nona-3,7-diene-endo-2,endo-6-diol, an Alicyclic Diol Whose Crystal-Structure Involves Two Types of Hydrogen-Bonded Columns." Australian Journal of Chemistry 44, no. 3 (1991): 343. http://dx.doi.org/10.1071/ch9910343.

Повний текст джерела

Анотація:

The crystal structure [C11H16O2, C2/c, a 32.19(1), b 7.648(1), c 20.101(8)Ǻ, β 126.63(1)°, Z 16] of 2,6-dimethylbicyclo[3.3.1] nona 3,7-diene-endo-2,endo-6-diol (7) was determined with final R 0.041. This structure is unlike the helical and layer arrangements reported earlier for related alicyclic diols with C2 symmetry, and is constructed from two types of double-stranded columns of diol molecules.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Wan, Debin, Christophe Morisseau, Bruce D. Hammock, and Jun Yang. "A Fast and Selective Approach for Profiling Vicinal Diols Using Liquid Chromatography-Post Column Derivatization-Double Precursor Ion Scanning Mass Spectrometry." Molecules 27, no. 1 (January 3, 2022): 283. http://dx.doi.org/10.3390/molecules27010283.

Повний текст джерела

Анотація:

Vicinal diols are important signaling metabolites of various inflammatory diseases, and some of them are potential biomarkers for some diseases. Utilizing the rapid reaction between diol and 6-bromo-3-pyridinylboronic acid (BPBA), a selective and sensitive approach was established to profile these vicinal diols using liquid chromatography-post column derivatization coupled with double precursor ion scan-mass spectrometry (LC-PCD-DPIS-MS). After derivatization, all BPBA-vicinal-diol esters gave a pair of characteristic isotope ions resulting from 79Br and 81Br. The unique isotope pattern generated two characteristic fragment ions of m/z 200 and 202. Compared to a traditional offline derivatization technique, the new LC-PCD-DPIS-MS method retained the capacity of LC separation. In addition, it is more sensitive and selective than a full scan MS method. As an application, an in vitro study of the metabolism of epoxy fatty acids by human soluble epoxide hydrolase was tested. These vicinal-diol metabolites of individual regioisomers from different types of polyunsaturated fatty acids were easily identified. The limit of detection (LOD) reached as low as 25 nM. The newly developed LC-PCD-DPIS-MS method shows significant advantages in improving the selectivity and therefore can be employed as a powerful tool for profiling vicinal-diol compounds from biological matrices.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Bell, KH, and LF Mccaffery. "Regioselective Monomethylation of Unsymmetrical Naphthalenediols With Methanolic HCl." Australian Journal of Chemistry 46, no. 5 (1993): 731. http://dx.doi.org/10.1071/ch9930731.

Повний текст джерела

Анотація:

Treatment of naphthalene-1,3-diol and naphthalene-1,7-diol with methanol containing dry hydrogen chloride at room temperature gives exclusively 3-methoxy-1-naphthol and 7-methoxy- 1-naphthol, respectively. Of the other two unsymmetrical naphthalenediols, the 1,2-isomer was unreactive and the 1,6-isomer gave a mixture of regioisomers under the same conditions. Two symmetrical diols (the 1,5- and 2,7-isomers) examined by the same procedure gave the monomethyl ethers in 60-70% yields.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Morikawa, Hiroshi, Jun-ichi Yamaguchi, Shun-ichi Sugimura, Masato Minamoto, Yuuta Gorou, Hisatoyo Morinaga, and Suguru Motokucho. "Systematic synthetic study of four diastereomerically distinct limonene-1,2-diols and their corresponding cyclic carbonates." Beilstein Journal of Organic Chemistry 15 (January 14, 2019): 130–36. http://dx.doi.org/10.3762/bjoc.15.13.

Повний текст джерела

Анотація:

In order to produce versatile and potentially functional terpene-based compounds, a (R)-limonene-derived diol and its corresponding five-membered cyclic carbonate were prepared. The diol (cyclic carbonate) comprises four diastereomers based on the stereochemical configuration of the diol (and cyclic carbonate) moiety. By choosing the appropriate starting compounds (trans- and cis-limonene oxide) and conditions, the desired diastereomers were synthesised in moderate to high yields with, in most cases, high stereoselectivity. Comparison of the NMR data of the obtained diols and carbonates revealed that the four different diastereomers of each compound could be distinguished by reference to their characteristic signals.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Zou, Jian Guo, Shi Ying Liu, Yong Yi Cao, and Zhi Hong Zhang. "Research on Synthesis Technology of Polyester Diol Using Vacuum Melting Method." Advanced Materials Research 988 (July 2014): 45–48. http://dx.doi.org/10.4028/www.scientific.net/amr.988.45.

Повний текст джерела

Анотація:

Using adipic acid, ethylene glycol and diethylene glycol as the main raw material, the polyester diol was prepared by vacuum melting method. The effects of the dosage of catalyst, the stuff molar ratio of diol and diacid, reaction temperature of the esterification reaction and other factors on the synthesis process of polyester diol were investigated. The optimal conditions of the polyester diol synthesis by vacuum melting method were determined as follows: the stuff molar ratio of diol and diacid 1.10:1, the dosage of catalyst 0.20‰ (the mass fraction of total amount of dicarboxylic acid and diols), the esterification reaction temperature 230 oC. Under such conditions, the esterification reaction time is 5.5 h to get qualified polyester polyol. Additionally, the structure characteristics of polyester glycol were studied by infrared spectrometer (FTIR) and thermogravimetric analyzer (TGA).

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Maskey, Rajendra P., Felix Huth, Iris Grün-Wollny, and Hartmut Laatsch. "2-Alkyl-3,4-dihydroxy-5-hydroxymethylpyridine Derivatives: New Natural Vitamin B6 Analogues from a Terrestrial Streptomyces sp." Zeitschrift für Naturforschung B 60, no. 1 (January 1, 2005): 63–66. http://dx.doi.org/10.1515/znb-2005-0110.

Повний текст джерела

Анотація:

The ethyl acetate extract of the strain Streptomyces sp. GW23/1540 has yielded four new 2-alkyl-5-(hydroxymethyl)pyridine-3,4-diols, 5-hydroxymethyl-2-isopropyl-pyridine-3,4-diol (1a), 5-hydroxymethyl-2-propyl-pyridine-3,4-diol (1b), 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c), and 5-hydroxymethyl-2-isobutyl-pyridine-3,4-diol (1d). Similarly, the strain Streptomyces sp. GW63/1571 afforded 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c) and another new natural product, (3aS, 7aR)-3a-hydroxy-3a,4,7,7a-tetrahydro-1-benzofuran-2(3H)-on e (3), together with anthranilic acid, anthranilamide, and phenylacetamide. The new natural products were inactive against three micro algae, the fungus Mucor miehei, the yeast Candida albicans, and the bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Streptomyces viridochromogenes.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Velíšek, J., M. Doležal, C. Crews, and T. Dvořák. "Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates." Czech Journal of Food Sciences 20, No. 5 (November 19, 2011): 161–70. http://dx.doi.org/10.17221/3527-cjfs.

Повний текст джерела

Анотація:

Protein hydrolysates produced by hydrochloric acid hydrolysis were analysed for 3-chloropropane-1,2-diol and its enantiomers. It was found that (R)-3-chloropropane-1,2-diol and (S)-3-chloropropane-1,2-diol were present in the hydrolysates in equimolar concentrations. Model experiments with glycerol, triolein and soy lecithin heated with hydrochloric acid in solution showed that these materials were precursors of 3-chloropropane-1,2-diol and 2-chloropropane-1,3-diol and, as expected, yielded racemic 3-chloropropane-1,2-diol. Yields of 3-chloropropane-1,2-diols decreased in the order triolein > lecithin > glycerol. The mechanisms of 3-chloropropane-1,2-diol enantiomers formation during the production of protein hydrolysates are presented and discussed as well as the reaction pathways of their decomposition in alkaline media via the corresponding intermediates, (R)- and (S)-glycidol, respectively. Both epoxides are hydrolysed to glycerol and form a variety of products with hydrolysate constituents.  

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Carvalho, CF, DP Arnold, RC Bott, and G. Smith. "1,1-Diphenylbutane-1,3-diol: the First Structurally Characterized Example of an Intramolecularly Hydrogen-Bonded Open-Chain 1,3-diol." Australian Journal of Chemistry 49, no. 11 (1996): 1251. http://dx.doi.org/10.1071/ch9961251.

Повний текст джерела

Анотація:

The crystal structure of the asymmetric 1,3-diol 1,1-diphenylbutane-1,3-diol has been determined and refined to a residual R of 0.039 for 795 observed reflections. Crystals are orthorhombic, space group P212121, with four molecules in a cell of dimensions a 9.625(4), b 16.002(3), c 8.834(3) Ǻ. The compound is unique among the known crystallographically characterized open-chain 1,3-diols in having only intramolecular hydrogen bonding involving the hydroxy groups [O-- -O 2.602(5) Ǻ].

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Hermes, Lena, Janis Römermann, Benedikt Cramer, and Melanie Esselen. "Phase II Metabolism of Asarone Isomers In Vitro and in Humans Using HPLC-MS/MS and HPLC-qToF/MS." Foods 10, no. 9 (August 29, 2021): 2032. http://dx.doi.org/10.3390/foods10092032.

Повний текст джерела

Анотація:

(1) Background: Metabolism data of asarone isomers, in particular phase II, in vitro and in humans is limited so far. For the first time, phase II metabolites of asarone isomers were characterized and human kinetic as well as excretion data after oral intake of asarone-containing tea infusion was determined. (2) Methods: A high pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-qTOF-MS) approach was used to identify phase II metabolites using liver microsomes of different species and in human urine samples. For quantitation of the respective glucuronides, a beta-glucuronidase treatment was performed prior to analysis via high pressure liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). (3) Results: Ingested beta-asarone and erythro and threo-asarone diols were excreted as diols and respective diol glucuronide conjugates within 24 h. An excretion rate about 42% was estimated. O-Demethylation of beta-asarone was also indicated as a human metabolic pathway because a corresponding glucuronic acid conjugate was suggested. (4) Conclusions: Already reported O-demethylation and epoxide-derived diols formation in phase I metabolism of beta-asarone in vitro was verified in humans and glucuronidation was characterized as main conjugation reaction. The excretion rate of 42% as erythro and threo-asarone diols and respective asarone diol glucuronides suggests that epoxide formation is a key step in beta-asarone metabolism, but further, as yet unknown metabolites should also be taken into consideration.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Giles, Robin G. F., Ivan R. Green, Yolanta Gruchlik, and Francois J. Oosthuizen. "Asymmetric Syntheses of Isochroman-4,7-diols Through Intramolecular Cyclization of Tethered Lactaldehydes." Australian Journal of Chemistry 53, no. 4 (2000): 341. http://dx.doi.org/10.1071/ch00020.

Повний текст джерела

Анотація:

Ready cyclization through silica gel chromatography of the asymmetric phenolic lactaldehyde (14) afforded the diastereomeric pair of isochroman-4,7-diols (21) and (23) in good yield, while (17), the benzylic epimer of (14), similarly yielded the isochroman-4,7-diol (25) as a single diastereomer.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Baroudi, Abdulkader, та Amir Karton. "Deciphering the exceptional selectivity of semipinacol rearrangements in cis-fused β-lactam diols using high-level quantum chemical methods". Organic Chemistry Frontiers 6, № 6 (2019): 725–31. http://dx.doi.org/10.1039/c8qo01092g.

Повний текст джерела

Анотація:

The semipinacol rearrangement mechanism in cis-fused β-lactam diols has been found to kinetically and thermodynamically favor acyl migration. The semipinacol rearrangement was also investigated for trans-fused β-lactam diol, in which the reversed selectivity that favors the alkyl migration was observed.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Ilavsky, M., H. Valentova, Z. Sedlakova, J. Nedbal, and V. Velychko. "Thermal, Dynamic Mechanical and Dielectric Behavior of Liquid-Crystalline Linear and Crosslinked Polyurethanes with Mesogenic Group in Side Chains." Materials Science Forum 518 (July 2006): 367–74. http://dx.doi.org/10.4028/www.scientific.net/msf.518.367.

Повний текст джерела

Анотація:

This paper describes DSC, dielectric and dynamic mechanical behavior of linear and crosslinked liquid crystalline (LC) polyurethanes based on LC diols with a mesogenic group in the side chain, diisocyanates of various flexibility and two triols. From our investigations it follows: a) Linear polymers prepared from diols with simple end side chain substituents (as hydrogen, nitro and nitril group) exhibit only amorphous behavior regardless of the structure of used diisocyanate; generally, the most pronounced LC behavior exhibited polymers prepared from a diol with phenyl substituent. b) Investigation of the curing reaction showed that rheological power-law parameters, which are characteristic of the structure at the gel point, are dependent on the initial ratio of the reactants (amount of LC diol in EANCs). c) Strong physical interactions between the mesogens support the cyclization in the course of crosslinking reaction. d) Introduction of chemical junctions (amount of triols) suppresses LC ordering in the networks.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Jha, G. S., P. Chhabra, G. Suri, M. Tyagi, P. Arora, G. Seshadri, and R. K. Khandal. "Study on Designing Sulfur Containing Bifunctional Building Block with Improved Refractive Index." E-Journal of Chemistry 6, no. 2 (2009): 399–411. http://dx.doi.org/10.1155/2009/634346.

Повний текст джерела

Анотація:

Sulfur and chlorine containing bifunctional diols with C-S bond has been prepared starting from chloroepoxy alkane and thioalcohol. The studies of FTIR, TLC, HPLC and NMR have been used to understand the reaction mechanism, as well as for optimization of the reaction parameters. The reaction is highly exothermic and the effect of temperature, rate of addition of reagents and reaction time are important factors affecting the formation of diol. Viscosity studies, HPLC, FTIR, NMR and acid number studies have shown that, these parameters could be used as process control parameters for the synthesis of diol. Refractive index of the synthesized diol is found to be higher than that of the reactants used.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Peci,, Lorenzo M., Robert V. Stick,, D. Matthew G. Tilbrook, and Merilyn L. Winslade. "The Asymmetric Dihydroxylation of Some Alkenyl b-D-Glucopyranosides: the Preparation of an Optically Pure Episulfide." Australian Journal of Chemistry 50, no. 11 (1997): 1105. http://dx.doi.org/10.1071/c97149.

Повний текст джерела

Анотація:

The asymmetric dihydroxylation of various alkenyl tetra-O-acetyl- β-D-glucopyranosides has given mixtures of diols which, in one instance, has yielded a pure diastereoisomer upon recrystallization. This optically pure diol has been converted into an episulfide, a putative inhibitor of β-D-glucan hydrolases

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Klinot, Jiří, Jan Sejbal, and Alois Vystrčil. "Triterpenoid 2,3-ketols, diols and their acetates: Preparation and conformation of the ring A." Collection of Czechoslovak Chemical Communications 54, no. 2 (1989): 400–412. http://dx.doi.org/10.1135/cccc19890400.

Повний текст джерела

Анотація:

19β,28-Epoxy-18α-oleanane derivatives I-III were converted into hydroxy ketones IV, VIII and X, acetoxy ketones V, VII, IX and XI, diols and their mono- and diacetates XII-XXV. Seven of the eight possible isomeric 2,3-diol monoacetates were obtained. Conformation of the ring A in these compounds has been derived from the 1H NMR and IR spectra. In 2β-acetoxy-3-ketone VII, 3α-hydroxy- and 3α-acetoxy-2-ketones VIII and IX, and in 2β,3α-diol monoacetates XVIII and XIX the ring A exists predominantly in a boat conformation.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Davis, Brian R., and Mark G. Hinds. "Synthetic, Structural and Vibrational Spectroscopic Studies in Bismuth(III) Halide/N,N′-Aromatic Bidentate Base Systems. IV. Bismuth(III) Halide/N,N′-Bidentate Ligand (1 : 1) Systems." Australian Journal of Chemistry 50, no. 4 (1997): 309. http://dx.doi.org/10.1071/c96107.

Повний текст джерела

Анотація:

The generation of a number of 1,2-diarylcyclopropane-1,2-diols is reported. Reaction of these in situ with acid gives, primarily, an α,β-unsaturated ketone in which the aryl substituent attached to the double bond is that which is best able to stabilize a benzylic cation. It is proposed that the reaction proceeds by O-protonation of the cyclopropane-1,2-diol, followed by loss of water and opening of the resulting cyclopropyl cation and final deprotonation. Such initial O-protonation contrasts with the C-protonation normally observed in the acidolysis of cyclopropanols and other dialkyl- and alkylaryl-cyclopropane-1,2-diols.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

An, Shujie, Guofeng Tang, Yaling Zhong, Li Ma та Qiancai Liu. "Novel π-expanded chrysene-based axially chiral molecules: 1,1′-bichrysene-2,2′-diols and thiophene analogs". Journal of Chemical Research 44, № 11-12 (26 квітня 2020): 641–45. http://dx.doi.org/10.1177/1747519820914837.

Повний текст джерела

Анотація:

1,1′-Bichrysene-2,2′-diol and its thiophene analogs, 6,6′-biphenanthro-[1,2- b]thiophene-7,7′-diols, as a series of novel π-expanded chrysene-/phenanthro[1,2- b]thiophene-based axially chiral molecules are synthesized from 1,1′-bi-2-naphthols with key steps including a Suzuki coupling, a Wittig reaction, and acid-mediated cyclization.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Li, Yuyang, and Ronald Kluger. "Metal-Catalyzed Site-Selective Monoacylation of Diols in Aqueous Media." Synthesis 51, no. 20 (August 12, 2019): 3784–91. http://dx.doi.org/10.1055/s-0037-1611907.

Повний текст джерела

Анотація:

Site-selective reactions of water-soluble biomolecules are being developed to produce efficient conversions in water and water/solvent mixtures. This review focuses on the use of designs based on bis-bidentate chelation of large metal ions by diols to be acylated by a co-chelated water-stable reagent. Topics discussed include: 1. The preparation and properties of water-stable acyl phosphate monoesters and their reactions with diol-chelated metal ions. 2. Site-selective monoaminoacylation of 3′-terminal diols of RNA and their applications in protein engineering. 3. Site-selective monoacylation of sugars with acyl phosphate monoesters associated with metal ions, including lanthanum and lead. The combination of metal ion, 1,2-diol, and acyl phosphate monoester produces site-selective reactions in aqueous media that can produce a general approach to site-selective mono-(amino)acylation in RNA and carbohydrates.1 Introduction2 Synthetic Aminoacylation of tRNA3 Activated Amino Acids in Water4 Metal Ions and Their Effects on the Reactivity of Acyl Phosphate Monoesters5 The Challenge of Site-Selective Acylation of Carbohydrates in Water6 Conclusions and Prospects

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Arnaud, Sacha Pérocheau, Linglin Wu, Maria-Angelica Wong Chang, James W. Comerford, Thomas J. Farmer, Maximilian Schmid, Fei Chang, Zheng Li, and Mark Mascal. "New bio-based monomers: tuneable polyester properties using branched diols from biomass." Faraday Discussions 202 (2017): 61–77. http://dx.doi.org/10.1039/c7fd00057j.

Повний текст джерела

Анотація:

A family of monomers, including 2,5-hexandiol, 2,7-octandiol, 2,5-furandicarboxylic acid (FDCA), terephthalic acid (TA), and branched-chain adipic and pimelic acid derivatives, all find a common derivation in the biomass-derived platform molecule 5-(chloromethyl)furfural (CMF). The diol monomers, previously little known to polymer chemistry, have been combined with FDCA and TA derivatives to produce a range of novel polyesters. It is shown that the use of secondary diols leads to polymers with higher glass transition temperatures (T_g) than those prepared from their primary diol equivalents. Two methods of polymerisation were investigated, the first employing activation of the aromatic diacids via the corresponding diacid chlorides and the second using a transesterification procedure. Longer chain diols were found to be more reactive than the shorter chain alternatives, generally giving rise to higher molecular weight polymers, an effect shown to be most pronounced when using the transesterification route. Finally, novel diesters with high degrees of branching in their hydrocarbon chains are introduced as potential monomers for possible low surface energy materials applications.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Jasmine, S., D. Reuben Jonathan, J. Sidharthan, and D. Roopsingh. "Fabrication and Characterization of Polyvinyl Chloride/Copolyester/Nanoclay Composite Nanofiber." Asian Journal of Chemistry 33, no. 8 (2021): 1868–74. http://dx.doi.org/10.14233/ajchem.2021.23269.

Повний текст джерела

Анотація:

Four random copolyesters were prepared by the polycondensation reaction of diols namely 1,5-dihydroxyanthraquinone, 4,4′-oxybis(benzoic acid) and variable chalcone diol. Four chalcone diols were produced by acid catalyzed Claisen-Schmidt reaction at room temperature. These random copolyesters were elucidated by solubility tests and viscosity measurements. The FT-IR, 1H & 13C NMR techniques were applied to establish the repeating units present in the copolyester backbone. Electrospinning method was employed to derive polyvinyl chloride-copolyester-nanoclay composite nanofiber from tetrahydrofuran medium. Scanning electron microscopy (SEM) was utilized to examine the morphology of the nanofibers. These composite nanofibers are expected to be a potential biomaterial of greater significance.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Logan, S. R. "Redox reactions with ferrocene/ferricenium species of radicals derived by H atom abstraction from alcohols and diols." Canadian Journal of Chemistry 69, no. 3 (March 1, 1991): 540–44. http://dx.doi.org/10.1139/v91-081.

Повний текст джерела

Анотація:

The effect of various alcohols and diols in diminishing the extent of the photo-oxidation of 4-ferrocenylbutanoate ion in the presence of N2O has been investigated. Where the hydroxyl radical generated in the photo-initiated electron transfer reacts with an alcohol by H atom abstraction at the α-position, the resulting radical is capable of reducing the ferricenium zwitterion to the ferrocenyl anion. Abstraction at other positions produces radicals that are essentially inert in this system and rate constants are derived for the reaction of OH with some such compounds. Non-vicinal diols behave similarly to the corresponding alcohols. With vicinal diols, a dehydration process, which occurs the more slowly the more highly substituted the diol, converts the radical -CR(OH)Ċ(OH)- into -ĊRCO-, which is an oxidizing species. The behaviour of pinacol was found to be anomalous. Key words: radical reactions, redox behaviour, alcohols.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Gao, Wei, Naiying Wu та Wenliang Sun. "Development and validation of a gas chromatography/mass spectrometry method for the determination of α- and ß-2, 7, 11-cembratriene-4, 6-diols in tobacco". World Journal of Engineering 13, № 4 (1 серпня 2016): 341–47. http://dx.doi.org/10.1108/wje-08-2016-045.

Повний текст джерела

Анотація:

Purpose This paper aims to present a robust method for the determination of α- and ß-2, 7, 11-cembratriene-4, 6-diols (α, ß-CBT-diol) in tobacco samples which was developed and validated by using the self-made α, ß-CBT-diol with higher purity as the standard. Design/methodology/approach After the ultrasonic extraction and clean-up procedures, samples were analyzed by gas chromatography/mass spectrometry in selected ion monitoring mode and full scan mode at the same time. A 1-heptadecanol was used as an internal standard. The important parameters, such as extraction conditions and derivation conditions, were optimized. Findings Under the optimal conditions, good results in terms of linearity (R2 > 0.999) and recoveries (93.2-107 per cent) were achieved. The limits of detection were 0.120 and 0.180 μg/ml for α- and ß-CBT-diol, respectively. α, ß-CBT-diol level of analyzed tobacco was found in the range of 34.2-1.26 × 103 μg/g with relative standard deviations below 6 per cent. Originality/value Such a strategy opens a new door towards the development of a simple, robust and sensitive method for the determination of α, ß-CBT-diol in real samples.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Xue, Dan, Xiaodong Fan, Zengping Zhang, and Wei Lv. "The Synthesis of Hydroxybutyrate-Based Block Polyurethane from Telechelic Diols with Robust Thermal and Mechanical Properties." Journal of Chemistry 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/9635165.

Повний текст джерела

Анотація:

A series of novel amphiphilic block polyurethanes (PUHE) have been successfully synthesized by solution polymerization of the derived PHB-diol and poly(ethylene glycol) with a coupling agent of 1,6-hexamethylene diisocyanate (HDI), while the PHB-diol was prepared via the transesterification of PHB and ethylene glycol. The hydroxyl contents in PHB-diols range from 1.36 to 1.99 (the molar ratio) as determined by nonaqueous titration. The molecular weight and chemical compositions of PUHE and PHB-diol were investigated by GPC,1H NMR, and FTIR in detail, which confirm the successful synthesis of PUHE. The tensile strength and elongation at break of PUHE could reach as high as 20 MPa and 210%, as the content of PHB in PUHE is 33%. TGA curves indicate that block-bonding between PHB-diol and PEG increases the thermal stability of PHB-diol. Film degradation of PUHE was studied by weight loss and scanning electron microscope (SEM). It could be concluded that degradation occurred gradually from the surface to the inside and that the degradation rate could be controlled by adjusting the PHB/PEG ratios. These properties make PUHE able to be used as a biodegradable thermoplastic elastomer.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Kulsiriswad, Santi, Kawee Srikulkit, and Onusa Saravari. "Effects of the Amount and Type of Diol Ring Openers on the Properties of Oligolactide Acrylates for UV-Curable Printing Inks." Coatings 7, no. 10 (October 20, 2017): 174. http://dx.doi.org/10.3390/coatings7100174.

Повний текст джерела

Анотація:

This study aimed to synthesize low viscosity oligolactide acrylates for UV-curable inks from oligolactide diols. Firstly, low molecular weight oligolactide diols were prepared by ring opening reaction of L-lactide with diols. Oligolactide acrylates were then synthesized by functionalizing the oligolactide diols with acrylic acid. In this study, three diol ring openers having short and long alkyl chain length were used to investigate the effects of the amount and type of diols on the properties of the oligolactide acrylates. The obtained oligomers were characterized, and the viscosities of oligolactide acrylates were measured. Results showed that oligolactide acrylates were successfully synthesized in all cases of ring openers, as confirmed by 1H-NMR (proton nuclear magnetic resonance spectroscopy) and FTIR (Fourier transform infrared spectroscopy). An increase in the alkyl chain length of the ring openers resulted in oligomers with lower viscosity and a decrease in Tg. Following that, the obtained oligolactide acrylates were employed for the formulation of UV-curable screen printing inks and their properties were investigated. Results showed that the inks formulated from oligomers with lower molecular weight exhibited better ink flow. Additionally, all ink films cured by UV radiation were very flexible with excellent adhesion, high impact resistance, and excellent water resistance.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Loehlin, James H., and Elizabeth L. N. Okasako. "Analysis of structures with saturated hydrogen bonding." Acta Crystallographica Section B Structural Science 63, no. 1 (January 15, 2007): 132–41. http://dx.doi.org/10.1107/s0108768106045046.

Повний текст джерела

Анотація:

All simple structures with saturated hydrogen bonding (SHB) are classified into eight categories on the basis of the donor and acceptor numbers on the atoms at each end of the hydrogen bonds. Examples from the literature are included where known, along with seven structures investigated as part of this study (five have SHB). Graph-set descriptions of the hydrogen-bond patterns are given for each of these structures and for some selected literature examples. The structures presented are: piperazine (I), morpholinium chloride (II) and iodide (III) [(II) and (III) are not SHB], three 1:1 cocrystals of diols with 1,4-phenylenediamine (PDA) – PDA·1,8-octane diol (IV), PDA·1,10-decane diol (V), and PDA·1,12-dodecane diol (VI) and 6-amino-1-hexanol (VII). This study discusses some structures that show limitations of the graph-set model, along with possible suggestions to cover these limitations. The cocrystalline PDA·aliphatic diol structures may provide details applicable to the structure of self-assembled monolayers of aliphatic thiol molecules on Au(111) surfaces.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Wang, Huan, Yanfei Zhao, Fengtao Zhang, Zhengang Ke, Buxing Han, Junfeng Xiang, Zhenpeng Wang, and Zhimin Liu. "Hydrogen-bond donor and acceptor cooperative catalysis strategy for cyclic dehydration of diols to access O-heterocycles." Science Advances 7, no. 22 (May 2021): eabg0396. http://dx.doi.org/10.1126/sciadv.abg0396.

Повний текст джерела

Анотація:

Dehydrative cyclization of diols to O-heterocycles is attractive, but acid and/or metal-based catalysts are generally required. Here, we present a hydrogen-bond donor and acceptor cooperative catalysis strategy for the synthesis of O-heterocycles from diols in ionic liquids [ILs; e.g., 1-hydroxyethyl-3-methyl imidazolium trifluoromethanesulfonate ([HO-EtMIm][OTf])] under metal-free, acid-free, and mild conditions. [HO-EtMIm][OTf] is tolerant to a wide diol scope, shows performance even better than H2SO4, and affords a series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines, dioxanes, and thioxane in high yields. Mechanism investigation indicates that the IL cation and anion serve as hydrogen-bond donor and acceptor, respectively, to activate the C─O and O─H bonds of alcohol via hydrogen bonds, which synergistically catalyze dehydrative cyclization of diols to O-heterocycles. Notably, the products could be spontaneously separated after reaction because of their immiscibility with the IL, and the IL could be recycled. This green strategy has great potential for application in industry.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Lombardi, Pamela J., Yonghong Gan, and David M. Lemal. "Synthesis and Chemistry of Highly Fluorinated Oxepane-2,7-diols." Collection of Czechoslovak Chemical Communications 67, no. 10 (2002): 1486–92. http://dx.doi.org/10.1135/cccc20021486.

Повний текст джерела

Анотація:

Reduction of dimethyl perfluoroadipate with Vitride yielded the title compounds, which were also prepared by dehydration of 1H,6H-perfluorohexane-1,1,6,6-tetrol. The configurations of the oxepanediols were assigned based on the crystal structure of the bis(tert-butyldiphenylsilyl) ether of the cis stereoisomer. Treatment with ethanolic HCl ring-opened the diols to 1H,6H-1,6-diethoxyperfluorohexane-1,6-diol, and dehydration with P4O10 gave perfluorohexanedial.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Gamba-Sánchez, Diego, and Joëlle Prunet. "Synthesis of 1,3-Diols by O-Nucleophile Additions to Activated Alkenes." Synthesis 50, no. 20 (August 30, 2018): 3997–4007. http://dx.doi.org/10.1055/s-0037-1610248.

Повний текст джерела

Анотація:

The diastereoselective synthesis of 1,3-diols by addition of oxygen nucleophiles to activated alkenes is presented. This review focuses on homoallylic alcohol substrates that react with a relay compound to form an intermediate oxygen nucleophile, which in turn will lead to a protected 1,3-diol by intramolecular addition to the olefin moiety.1 Introduction2 Base Catalysis3 Organocatalysis4 Activation with Non-Metallic Electrophiles5 Activation with Transition Metal Derivatives6 Conclusions

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Piccialli, Vincenzo. "(±)-((2S,5R)-5-(Acetoxymethyl)tetrahydrofuran-2-yl)methyl Benzoate." Molbank 2022, no. 1 (March 4, 2022): M1349. http://dx.doi.org/10.3390/m1349.

Повний текст джерела

Анотація:

In this note we report the synthesis of a doubly acylated cis-THF-diol product synthesised in three steps by the stereoselective RuO4-catalysed oxidative cyclisation of 1,5-hexadiene, followed by benzoylation and acetylation. This substance is one of the substrates chosen to probe a new developed oxidative procedure to transform bis-acylated THF-diols into bis-acylated 1,4-diketones. This new derivative was fully characterised by spectroscopic methods.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Komarov, Pavel D., Mikhail E. Minyaev, Andrei V. Churakov, Dmitrii M. Roitershtein, and Ilya E. Nifant'ev. "(1R,2S,4r)-1,2,4-Triphenylcyclopentane-1,2-diol and (1R,2S,4r)-4-(2-methoxyphenyl)-1,2-diphenylcyclopentane-1,2-diol: application as initiators for ring-opening polymerization of ∊-caprolactone." Acta Crystallographica Section E Crystallographic Communications 75, no. 7 (June 21, 2019): 1035–40. http://dx.doi.org/10.1107/s2056989019008673.

Повний текст джерела

Анотація:

Reductive cyclization of 1,3,5-triphenyl- and 3-(2-methoxyphenyl)-1,5-diphenylpentane-1,5-diones by zinc in acetic acid medium leads to the formation of 1,2,4-triphenylcyclopentane-1,2-diol [1,2,4-Ph3C5H5-1,2-(OH)2, C23H22O2, (I)] and 4-(2-methoxyphenyl)-1,2-diphenylcyclopentane-1,2-diol [4-(2-MeOC6H4)-1,2-Ph2C5H5-1,2-(OH)2, C24H24O3, (II)]. Their single crystals have been obtained by crystallization from a THF/hexane solvent mixture. Diols (I) and (II) crystallize in orthorhombic (Pbca) and triclinic (P\overline{1}) space groups, respectively, at 150 K. Their asymmetric units comprise one [in the case of (I)] and three [in the case of (II)] crystallographically independent molecules of the achiral (1R,2S,4r)-diol isomer. Each hydroxyl group is involved in one intramolecular and one intermolecular O—H...O hydrogen bond, forming one-dimensional chains. Compounds (I) and (II) have been used successfully as precatalyst activators for the ring-opening polymerization of ∊-caprolactone.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Hu, Jiong, Rüdiger Popp, Timo Frömel, Manuel Ehling, Khader Awwad, Ralf H. Adams, Hans-Peter Hammes, and Ingrid Fleming. "Müller glia cells regulate Notch signaling and retinal angiogenesis via the generation of 19,20-dihydroxydocosapentaenoic acid." Journal of Experimental Medicine 211, no. 2 (January 20, 2014): 281–95. http://dx.doi.org/10.1084/jem.20131494.

Повний текст джерела

Анотація:

Cytochrome P450 (CYP) epoxygenases generate bioactive lipid epoxides which can be further metabolized to supposedly less active diols by the soluble epoxide hydrolase (sEH). As the role of epoxides and diols in angiogenesis is unclear, we compared retinal vasculature development in wild-type and sEH−/− mice. Deletion of the sEH significantly delayed angiogenesis, tip cell, and filopodia formation, a phenomenon associated with activation of the Notch signaling pathway. In the retina, sEH was localized in Müller glia cells, and Müller cell–specific sEH deletion reproduced the sEH−/− retinal phenotype. Lipid profiling revealed that sEH deletion decreased retinal and Müller cell levels of 19,20–dihydroxydocosapentaenoic acid (DHDP), a diol of docosahexenoic acid (DHA). 19,20-DHDP suppressed endothelial Notch signaling in vitro via inhibition of the γ-secretase and the redistribution of presenilin 1 from lipid rafts. Moreover, 19,20-DHDP, but not the parent epoxide, was able to rescue the defective angiogenesis in sEH−/− mice as well as in animals lacking the Fbxw7 ubiquitin ligase, which demonstrate strong basal activity of the Notch signaling cascade. These studies demonstrate that retinal angiogenesis is regulated by a novel form of neuroretina–vascular interaction involving the sEH-dependent generation of a diol of DHA in Müller cells.

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Dioll"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями