Identification Of Esters Research Articles

Regioselective Synthesis of 2,3-Disubstituted Indoles via Interrupted Heyns Rearrangement Involving C-C Bond Cleavage.

A novel metal free, Brønsted acid mediated and operationally simple strategy has been developed for regioselective synthesis of 2,3-disubstituted indoles from α-hydroxyketones and o-aminoaryl ketones in excellent yields. The reaction proceeds via interrupted Heyns rearrangement through the generation of aminoenol intermediate followed by intramolecular trapping and aromatization with C-C bond cleavage and release of corresponding ester. The mechanism was further supported by the identification of ester in GCMS and reaction of cyclic α-hydroxydimethylketal, which afforded ester tethered indole derivative.

Chromatographic identification of esters on the basis of fatty acids with alcohols

Chromatographic identification of esters on the basis of fatty acids with alcohols

Separation and identification of esters from ultrasonic extraction of Shengli lignite in a toluene/ethanol mixed solvent

ABSTRACTShengli lignite (SL) was extracted with toluene/ethanol at the condition of ultrasonic oscillation and the dissolved matters were further separated with column chromatography. Twenty-two esters, including three isomers of benzylbenzoate, a pure compound of bis(6-methylheptyl) phthalate, and eighteen substances of phenylcarbonate were obtained and then analyzed with gas chromatography/mass spectrometry (GC/MS). The isolation and analysis of these high-valued organic compounds could provide an important theoretical basis for the nonfuels of lignite.

Identification of Esters as Novel Aggregation Pheromone Components Produced by the Male Powder-Post Beetle, Lyctus africanus Lesne (Coleoptera: Lyctinae).

Lyctus africanus is a cosmopolitan powder-post beetle that is considered one of the major pests threatening timber and timber products. Because infestations of this beetle are inconspicuous, damage is difficult to detect and identification is often delayed. We identified the chemical compounds involved in the aggregation behavior of L. africanus using preparations of crude hexanic extracts from male and female beetles (ME and FE, respectively). Both male and female beetles showed significant preferences for ME, which was found to contain three esters. FE was ignored by both the sexes. Further bioassay confirmed the role of esters in the aggregation behavior of L. africanus. Three esters were identified as 2-propyl dodecanoate, 3-pentyl dodecanoate, and 3-pentyl tetradecanoate. Further behavioral bioassays revealed 3-pentyl dodecanoate to play the main role in the aggregation behavior of female L. africanus beetles. However, significantly more beetles aggregated on a paper disk treated with a blend of the three esters than on a paper disk treated with a single ester. This is the first report on pheromone identification in L. africanus; in addition, the study for the first time presents 3-pentyl dodecanoate as an insect pheromone.

Identification of esters by collisional charge inversion of their enolate ions

AbstractThe collisional charge inversion and neutralization‐reionization (−NR) mass spectra of the enolate ions of m/z 115 derived from the four butyl acetates, the two propyl propionates, ethyl butyrate, ethyl isobutyrate, methyl valerate, methyl 2‐methylbutyrate and methyl 3‐methylbutyrate were recorded. The major primary fragmentation reactions of the unstable carbenium ion formed by charge inversion involve elimination of an alkoxy radical to form a ketene or alkylketene molecular ion and formation of an alkyl ion consisting of the R1 group of RCOOR1. A minor fragmentation reaction involves elimination of an alkyl radical by cleavage of a CC bond α to the ether oxygen. The alkylketene ions fragment by β‐cleavage eliminating an alkyl radical to form an olefinic acylium ion. In most cases the charge inversion mass spectra of the enolate ions allow identification of the ester.

Studies on the possibility of utilizing the metod of pyrolytic capillary gas-liquid chromatography in the identification of ester - ether elastomer

Studies on the possibility of utilizing the metod of pyrolytic capillary gas-liquid chromatography in the identification of ester - ether elastomer

A Fast, Simple Method for Analysis of Phenoxy Acid Salt and Ester Formulations by High Performance Liquid Chromatography

Abstract Salt formulations of 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) and dichlorprop [2-(2,4-dichlorophenoxy)propanoic acid] have been analysed by reversed-phase HPLC using a C18-column with 50:50 (v/v) acetonitrile/2% acetic acid as eluant. Internal and external standard HPLC methods are compared. Ester formulations of 2,4-D and 2,4,5–T are analysed, without hydrolysis, on the same column using 60:40 (v/v) acetonitrile/2% acetic acid as eluant. The method has been used in this laboratory to determine free phenoxy acid in ester formulations, and for the identification of esters in mixed ester formulations. The methods are fast and accurate, and offer some advantages over previously-described methods.

Synthesis and identification of esters of isomeric tetrahydropyranyl-substituted 1-aryltriazolecarboxylic acids

The reaction of (2,2-dimethyltetrahydropyran-4-yl)propiolic acid esters with p-fluorophenyl azide leads to esters of isomeric tetrahydropyranyl-substituted 1-aryltriazolecarboxylic acids, which were identified by means of conversion to disubstituted triazoles; their structures were proved by physicochemical methods.

Esters from Bacterial Oxidation of Olefins

Identification of esters isolated from culture fluids of bacteria growing upon terminal olefins indicates that bacteria oxidize olefins at the saturated methyl group, leaving the double bond intact. The yeast Candida lipolytica produces alpha-glycols from olefins, presumably by attacking the double bond.