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INDUSTRIAL ORGANIC SOLVENTS
Published in Nicholas P. Cheremisinoff, Industrial Solvents Handbook, Revised And Expanded, 2003
The chief functional group for the ether family is the O-R group called the alkoxy group. The general structure for ethers is R-O-R*. Symmetrical ethers are those where the alkyl groups, R and R', are the same. Asymmetrical ethers are those where the R and R' are different. Simple ethers can be named by naming the alkyl groups alphabetically followed by the word "ether". For example, CHrO-CHrCH1 would be called using this common name approach as ethyl methyl ether. However for more complex ethers that have branching, using this common name approach is considerably more difficult. The IUPAC has come up with some rules that allow the naming of complex ethers. The rules are similar to those used in naming alcohols except the O-R group is named as any other branched group. Using the rules for alkanes, alkenes, or alkynes with the alkoxy groups identified on the longest continuous chain. The rules are as follows:
Renewables—The Future’s (only) Hope!
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
The most practical method for making ethers is the Williamson ether synthesis, which uses an alkoxide ion to attack an alkyl halide, substituting the alkoxy (-O-R) group for the halide. The alkyl halide must be unhindered (usually primary), or elimination will compete with the desired substitution.
The Other Energy Markets
Published in Anco S. Blazev, Global Energy Market Trends, 2021
The most practical method for making ethers is the Williamson ether synthesis, which uses an alkoxide ion to attack an alkyl halide, substituting the alkoxy (-O-R) group for the halide. The alkyl halide must be unhindered (usually primary), or elimination will compete with the desired substitution.
Study on the Synergistic Antioxidant Effect of Coal Inhibitors and the DFT Calculation
Published in Combustion Science and Technology, 2023
Yichao Yin, Yinghua Zhang, Zhian Huang, Hao Ding, Xiangming hu, Yukun gao, Yifu Yang
In the oxidation process of coal treated with a compound inhibitor, the inhibition mechanism is shown in Figure 14. First, the gel covered and filled the coal body, isolating oxygen and slowing down the heating of the coal body. VE or EGCG reacted with the peroxide radical (ROO•) in the coal to produce hydrogen peroxide. With the increase of temperature, on the one hand, VE and EGCG captured hydroxyl radical (HO•) and alkoxy groups (RO•), and other intermediates generated by the decomposition of hydroperoxides to form water and alcohol, and the alcohol formed a stable ether structure under the action of antioxidants. On the other hand, VE and EGCG slowed down the hydrogen supply reaction of the aliphatic hydrocarbon and carboxyl group to hydroxyl radicals. Therefore, the compound inhibitor can prevent the further oxidation of the active group. At the same time, VE can reduce part of TP to capture peroxide radicals (ROO•), and TP can capture VE• to regenerate VE, thus prolonging the inhibitory action time of VE. In conclusion, as a compound inhibitor, the mixture of TP and VE loaded with hydrogel can effectively eliminate the activity of oxygen-containing free radicals, destroy the free radical chain reaction of coal oxidation, and thus inhibit the spontaneous combustion oxidation of coal.
Cholesterol-based nonsymmetric dimers comprising phenyl 4-(benzoyloxy)benzoate core: the occurrence of frustrated phases
Published in Liquid Crystals, 2021
Channabasaveshwara V. Yelamaggad, Sachin A. Bhat
Cholesterol was treated with either 4-bromobutyroyl chloride, 5-bromopentanoyl chloride, 6-bromohexanoyl chloride or 8-bromooctanoyl chloride in the presence of a mild base (pyridine) in THF to obtain cholesteryl ω-bromoalkanoates (1a–d). [11,13–15,17–20,52–56] These products were reacted with hydroquinone under the Williamson ether synthesis protocol to obtain cholesteryl ω-(4’-hydroxyphenyl-4-oxy)-alkanoates (2a–d). Ethyl 4-hydroxybenzoate was subjected to O-alkylation using the requisite n-alkyl bromides to obtain 4-(n-alkoxy)ethyl benzoates (3a–d). Subsequently, these esters were hydrolysed using 20% of aqueous sodium hydroxide in ethanol to obtain 4-(n-alkoxy)benzoic acids (4a–d). The 4-(n-alkoxy)benzoic acids (4a–d) thus obtained were coupled with 4-hydroxybenzaldehyde using a DCC coupling agent in the presence of DMAP to get 4-formylphenyl 4-(n-alkoxy)benzoates (5a–d); these were converted to 4-((4-(n-alkoxy)benzoyl)oxy)benzoic acids (6a–d) using Jones reagent. The synthesis of final products belonging to CPD-n,m series was achieved by coupling the phenols 2a–d with the acids 6a–d in the presence of DCC and DMAP in THF. Spectroscopic analyses and microanalytical data characterised the molecular structures of the target compounds and their intermediates. The detailed synthetic protocol along with the characterisation data for the dimers is given in experimental section 5.
Molecular structure and the twist-bend nematic phase: the role of terminal chains
Published in Liquid Crystals, 2020
Jordan P. Abberley, Rebecca Walker, John M. D. Storey, Corrie T. Imrie
The melting points of the four series, MeOB6O.m, MeOB6O.Om, CB6O.m, and CB6O.Om, are compared in Figure 9. The MeOB6O.Om series shows the highest melting points for all values of m. The melting points of the MeOB6O.m dimers are higher than the corresponding members of the CB6O.m series except for the propyl homologues for which CB6O.3 has a marginally higher melting point than MeOB6O.3. For shorter terminal chains, the CB6O.Om dimers show the second highest melting points but these fall quickly as m is increased and for the higher values of m the melting points of the corresponding members of the CB6O.m, and CB6O.Om series are very similar and lower than those of the MeOB6O.m series. These data support the general observation that the methoxy group promotes higher melting points than a nitrile terminal group [62–64], and dimers having terminal alkoxy chains have higher melting points than the corresponding alkyl substituted materials [23,50]. These trends may be attributed to the more efficient packing of the methoxy group and alkoxy chains compared to the nitrile and alkyl chains, respectively, and the enhanced polar interactions between alkoxy chains.