Methoxy ethyl acrylate group

An important step forward in the development of oil-resistant acrylic rubbers for use at low temperatures was the recognition that if a —CH — group in the ester side chain was replaced by an —O— or —S— linkage both the Tg and the degree of swelling in solvents were reduced (Lawler et al, 1968). This has led to the commercial development of rubbers which are copolymers of either ethyl or butyl acrylate with an alkoxyalkyl acrylate comprising some 20-50% of the total composition. Typical of such alkoxy compounds are methoxy ethyl acrylate (VI) and ethoxy ethyl acrylate (VII) ... 

Polyacrylate elastomers may consist of one or more of the following monomers ethyl acrylate, EA butyl acrylate, BA and methoxy ethyl acrylate MEA, the structures of which are given in Figure 5.1. These are coupled with cure sites, which may be reactive halogens, epoxy or carboxyl groups, or combinations thereof, as seen in Figure 5.2. [1,6,11]. 

The ethyl acrylate group provides the best heat and oil resistance but is deficient in low-temperature flexibility. Butyl acrylate will give low-temperature properties down to —40°C, but the oil resistance is poorer. The methoxy ethyl acrylate (MEA), when combined with EA and BA, results in a much-improved balance of oil and low-temperature resistance. Figure 5.3 demonstrates the property balance obtained with the various combinations of EA, BA, and MEA [6]. 

Acyclic Reagents. The alkenylation protocol between styrene, ethyl acrylate, or acrylonitrile and a 5-bromo- and 5-iodopyrimidine leads to coupling products 275 (Scheme 98) [143] Methoxy-, methylthio-, and amino groups are tolerated. i A triflyloxy substituent may replace the iodo substituent. 1-Methyl- and l,3-dimethyluracil-5-yl triflate... 

The Diels-Alder reactions of the methyl or ethyl ester of benzenesulfonylindole-2-acrylic acid with several l-alkoxycarbonyl-l,2-dihydropyridines are reported and only a single stereoisomer was obtained, as in the case of l-methoxy(ethoxy)-carbonyl-1,2-dihydropyridines. However, when the Diels-Alder reaction of 17 was carried out with 8g[R = (CHsjsC], a mixture of two stereoisomers 18gand25were obtained in a 1 1 ratio (65% total yield). The bulky rerr-butyl group creates sufficient steric interference with the indole ring to cause the loss of stereochemistry ... 

Methyl esters are always the preferred substrates, conversions being lower with, for example, ethyl esters. Functional groups such as nitro, methoxy, alkenyl and pyridyl are compatible with the reaction conditions. Diesters can only be effective if bis-transesterification is desired, when an excess of the alcohol (e.g., 3-5 equiv) is necessary. Methyl acrylate tends to polymerize under the reaction conditions, but the use of an excess of the ester (3-5 equiv) and lower temperatures (-10°C) allows efficient isolation of the required ester. 

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