Aromatic Methyl Esters Research Articles

Aromatic vs aliphatic methyl esters : Preferential hydrolysis of latter by pig liver esterase

Aromatic vs aliphatic methyl esters : Preferential hydrolysis of latter by pig liver esterase

Selectivity in enzyme catalysed reactions: Preferential hydrolysis of a phenolic acetate in the presence of an aromatic methyl ester by pig liver esterase

Selectivity in enzyme catalysed reactions: Preferential hydrolysis of a phenolic acetate in the presence of an aromatic methyl ester by pig liver esterase

One pot synthesis of aromatic methyl esters by electrochemical oxidation of aldehydes mediated by biscoenzyme catalysis

One pot synthesis of aromatic methyl esters by electrochemical oxidation of aldehydes mediated by biscoenzyme catalysis

Oxygen-17 NMR spectroscopy: torsion angle relationships in aryl carboxylic esters, acids and amides

/sup 1/ /sup 7/O NMR spectroscopic data (natural abundance in acetonitrile at 75/sup 0/C) were obtained for the following series of electronically similar, sterically hindered compounds: aromatic methyl esters, aromatic carboxylic acids, and aromatic amides. Torsional angles were calculated by the molecular mechanics (MM2) method. Linear regression analysis of the estimated torsion angles and the /sup 17/O chemical shift data for each series yielded the following results (series, slope delta/degree, correlation coefficient): esters (C=O), 0.70, 0.997; esters (-0-), 0.43, 0.992; acids (-CO/sub 2/H), 0.56, 0.994; amides (C=O), 0.84, 0.942; N,N-dimethylamides (C=O), 0.6, 0.991. The results are discussed in terms of minimization of repulsive van der Waals interactions by rotation of the functional group out of the plane of the aromatic ring.

Dienamines as Diels-Alder dienes. A novel benzannulation sequence

Diels-Alder reaction between (E)-dienamines 1, – 7 and methyl propiolate followed by elimination of Me 2NH from the intermediate cycloadducts III affords the aromatic methyl esters 8, – 14 in good yield.

Novel extracellular enzymes (ligninases) of Phanerochaete chrysosporium

3 New spectrophotometric enzyme assays were developed for the study of microbial lignin-degrading enzymes. The conversion of 2-methoxy-3-phenylbenzoic acid to 2-hydroxy-3-phenylbenzoic acid led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white-rot fungus Phanerochaete chrysosporium. The conversion of methyl 2-hydroxy-3-phenylbenzoate to 2-hydroxy-3-phenylbenzoic acid allowed the identification of an extracellular, aromatic methyl ester esterase produced by this fungus. The Phanerochaete sp. also excreted an enzyme complex that oxidized 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one, probably to aliphatic products. All 3 novel enzyme activities were produced together with, and probably comprise a part of, the Phanerochaete ligninolytic enzyme complex. Unlike previously known ligninases, these enzymes did not oxidize 3,4-dimethoxybenzyl alcohol. All 3 were H2O2-dependent and were activated by Mn2+ ions.

Novel extracellular enzymes (ligninases) ofPhanerochaete chrysosporium

3 New spectrophotometric enzyme assays were developed for the study of microbial lignin-degrading enzymes. The conversion of 2-methoxy-3-phenylbenzoic acid to 2-hydroxy-3-phenylbenzoic acid led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white-rot fungus Phanerochaete chrysosporium. The conversion of methyl 2-hydroxy-3-phenylbenzoate to 2-hydroxy-3-phenylbenzoic acid allowed the identification of an extracellular, aromatic methyl ester esterase produced by this fungus. The Phanerochaete sp. also excreted an enzyme complex that oxidized 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one, probably to aliphatic products. All 3 novel enzyme activities were produced together with, and probably comprise a part of, the Phanerochaete ligninolytic enzyme complex. Unlike previously known ligninases, these enzymes did not oxidize 3,4-dimethoxybenzyl alcohol. All 3 were H2O2-dependent and were activated by Mn2+ ions.

Long-chain phenols. Part 18. Conversion of anacardic acid into urushiol

(15 : 0)-Anacardic acid (6-pentadecylsalicylic acid), prepared by reduction of unsaturated anacardic acid from Anacardium occidentale, has been converted into anacardic alcohol (6-pentadecylsalicyl alcohol) and thence by oxidation at carbon into anacardaldehyde. Phenolic oxidation of anacardic alcoholled to 8-pentadecyl-1-oxaspiro-[2.5]octa-5,7-dien-4-one, itself readily convertible photochemically, but less so thermally, into anacardaldehyde. Reaction of thionyl chloride with anacardic acid led mainly to the anhydride, which by hydride reduction gave anacardaldehyde less satisfactorily. Dakin oxidation of anacardaldehyde furnished (15 : 0)-urushiol (3-pentadecylcatechol) identical chemically and from argentation t.l.c. with the hydrogenated natural product from Rhus vernicifera. (15 : 0)-Cardanol (3-pentadecylphenol) has been detected in hydrogenated urushiol. The composition of the unsaturated constituents of urushiol from Rhus vernicifera and Rhus toxicodendron and its mode of formation have been discussed. An improved synthesis of (15 : 0)-urushiol has been devised based on an organolithium route. Aromatic methyl ether and ester formation in this series is greatly facilitated by phase-transfer catalysis.

A novel method for correlation of substituent constants in some aromatic esters using the shift reagent Eu(fod) 3

The lanthanide induced chemical shifts of the ester methyl group were studied in eighteen m-, and p-substituted aromatic methyl esters with varying amounts of added shift reagent, Eu(fod) 3. Each time the lanthanide induced shift (LIS) was plotted against the molar ratio of shift reagent (SR)/substrate and a straight line was obtained upto one mole ratio of added shift reagent. The slopes of these plots correlated well with the Hammett's σ constants and yield a value of −4.95 for the reaction constant ϱ. The method is therefore one of the simplest ways of correlating the substituent constants in aromatic esters.

General molecular weight‐lowering side reaction in the thermal condensation of aromatic methyl esters with aromatic amines and hydrazides

AbstractThe direct thermal condensation of aromatic methyl esters with aromatic amines and hydrazides was studied. Using model compounds, it was learned that N‐methylation of amines (both aromatic and aliphatic) and hydrazides is inherent at temperatures required for condensation polymerization. This side reaction prevents attainment of high molecular weight polyamides, polyhydrazides, or polyoxadiazoles from the corresponding difunctional aromatic monomers by heat alone. Reported catalysts for the condensation reaction do not prevent the side reaction.

Thermal reactions of methyl linoleate. II. The structure of aromatic C18 methyl esters

This second report describes the characterization of C(18) aromatic esters from the heated linoleate and the independent synthesis of two of them. The esters were isolated by a combination of molecular distillation, urea adduction, column chromatography, and gas chromatography. They were characterized by infrared, ultraviolet, NMR, and mass spectroscopy. The analytical data for the isolated esters were compared with the data for the synthetic esters, methyl 11-(2'-methylphenyl) undecanoate, methyl 7-(2'-pentylphenyl) heptanoate, and methyl 8-(2'-butylphenyl) octanoate. The latter two compounds were found to be components of the aromatic fraction isolated from heated linoleate, and their synthesis is deseribed in detail.