Homologue ester

Arndt-Eistert synthesis A procedure for converting a carboxylic acid to its next higher homologue, or to a derivative of a homologous acid, e.g. ester or amide. 

The Arndt-Eistert reaction is a comparatively simple method for converting an acid Into its next higher homologue or to a derivative of the homologous acid, such as an amide or an ester. The overall yield is generally good. The reaction... 

As is not uncommon in homologous series, close homologues sometimes showed anomalous behaviour, e.g., of the benzilic acid esters with the following basic components —... 

The property of producing local anresthesia is also sho-wn by other products than alkamine esters, e.g., benzyl alcohol and its homologues, saligenin, and the esters of aminoaromatic acids such as the ethyl and diethylaminoethyl esters of 4-aminobenzoie acid. 

Phenyl-propyl alcohol, CgH. CHj. CH.2. CHj. OH, is the next highest homologue of phenyl-ethyl alcohol, and is also known as hydro-cinnamyl alcohol. Like the last described bodies it has been known for many years, its first preparation being described in the Aivnalen (188, 202). It occurs as a cinnamic acid ester in storax, and as an acetic ester in cassia oil. It is prepared synthetically by the reduction of cinnamyl alcohol with sodium amalgam and water, or by the reduction of cinnamic or benzyl acetic esters with sodium and absolute alcohol. It has the following characters —... 

Ethyl Salicylate.—The ethyl ester of salicylic acid resembles the lower homologue, methyl salicylate, in its general characters and perfume value. It is an oil of specific gravity 1 1372, refractive index 1-52338, and optically inactive. It boils at 234°. It solidifies at low temperatures, and melts at 1-3°. 

The transformation of l-methylthio-l-(methylsulfonyl)alkanes (254) to methyl esters can be efficiently carried out by oxidation or by a-chlorination followed by methanolysis (equation 152)145. The lithium or the sodium salt of (phenylsulfonyl)nitromethane (256) is a very useful reagent for the preparation of higher homologues of nitromethanes by alkylation since the salts are air insensitive, non-hygroscopic, and easily handled without decomposition. The oxidation of the resulting secondary a-nitro sulfone (257) gives... 

Low-coordinate species of the main group elements of the second row such as carbenes, olefins, carbonyl compounds (ketones, aldehydes, esters, amides, etc.), aromatic compounds, and azo compounds play very important roles in organic chemistry. Although extensive studies have been devoted to these species not only from the physical organic point of view but also from the standpoints of synthetic chemistry and materials science, the heavier element homologues of these low-coordinate species have been postulated in many reactions only as reactive intermediates, and their chemistry has been undeveloped most probably due to... 

Crotonic esters and certain homologues, when converted to their enolates with LDA and treated with stannyl and germyl chlorides, afford the y-metallo derivatives (Table 10)57. In contrast, silylation of these enolates leads to the 0-silyl derivatives. Interestingly, the halostannane derivatives show a strong preference for the (Z) geometry suggestive of a donor-acceptor interaction between the carbonyl oxygen and the electropositive tin atom,... 

Theses polymers are made from acrylic acid, its homologues and their derivatives. Glass like resins were made from esters of aerylic acid in 1877 by Fitting and Peter by Kahlbaum. In 1928, Rohm and Hass, a German Company started commercial development of methacrylic esters. Limited production started in 1933. The rapidly expanding air-force used this plastic in place of glass in the aeroplanes. Most of the early production of "Plexiglass was used up by air-force planes. In 1936, ICI marketed methyl methacrylate sheets as "Perspex". 

The above evidence strongly suggests that the pseudocationic reactions involve the ester 1-phenylethyl perchlorate and its oligomeric homologues as catalyst. It also shows that the ester is only stable when an excess of styrene is present in the reaction mixture. Spectroscopic and conductimetric studies on the present system confirmed this interpretation and indicated that at least four molecules of styrene are required for the stabilisation of one molecule of ester. Details of the experiments carried out to investigate the stoicheiometry of ester stabilisation will be given in a later paper. The mode of this stabilisation is not clear at present and we do not known the location of the four styrene molecules with respect to the ester. 

Our interpretation of these phenomena is as follows the ester styryl perchlorate is not stable alone in solution, but this ester and its oligomeric homologues do exist in the presence of excess styrene, consequently the styrene must stabilise the ester. Presumably it does this by being co-ordinated (probably to the oxygen atoms) and thus reduces the polarity of the ester carbon-oxygen bond. It is not known yet whether any other compounds can exert the same effect. 

Ethoxylated sorbitan ester surfactant mixtures like Tween 20 (cf. Fig. 2.9.38) were often used in biochemical applications. Detergents of this type were analysed by MALDI MS. The aim was to compare the separation results of TLC and RP-LC and to detect impurities within these ethoxylated sorbitan esters [30], Tween 20, the ethoxylated sorbitan carboxylate was ionised resulting in [M + Na]+ and [M + K]+ ions. The Tween 20 isomeric and homologue molecules contained a varying number of ethoxylate units. The number of EO units (-CH2CH2O-) was determined from 18 to 34 resulting in Am/z 44 equally spaced signals [30]. 

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