Increasing methacrylic acid substitution

Alternatively, esterification of carboxylic acid can be carried out in aqueous media by reacting carboxylic acid salts with alkyl halides through nucleophilic substitutions (Eq. 9.10).20 The reaction rate of alkyl halides with alkali metal salts of carboxylic acids to give esters increases with the increasing concentration of catalyst, halide, and solvent polarity and is reduced by water. Various thymyl ethers and esters can be synthesized by the reactions of thymol with alkyl halides and acid chlorides, respectively, in aqueous medium under microwave irradiation (Eq. 9.11).21 Such an esterification reaction of poly(methacrylic acid) can be performed readily with alkyl halides using DBU in aqueous solutions, although the rate of the reaction decreases with increasing water content.22... 

Heteropoly catalysts have significant activities for the oxidation of isobutane into methacrolein and methacrylic acid. The yield increased up to 6% by vanadium substitution or salt formation, as follows. With Cs2.5Ni0.08H0.34+JrPV,Mo12 - O40, the highest conversion and selectivity were observed at x 1 (355). Increases in the reaction temperature to 613 K led to increased yields, up to 9.0%. A similar increase in the yield resulted from the substitution of As for P as a heteroatom or from the addition of various transition metals (106, 356). 

Adhesives based on Neoprene AF, a reactive copolymer of chloroprene and methacrylic acid, are characterized by faster bond strength development (Fig. 1), increased heat resistance, and better resistance to phasing than the fast-crystallizing types. However, because of its reactivity, the use of Neoprene AF requires special attention to processing, compounding, and raw polymer inventory control. If it is substituted directly into a formulation based on Neoprene AC or AD, the results may be disappointing. 

Films were first cast from the methacrylate end capped siloxanes with 12.5 mole%, 25 mole %, 40 mole % and 65 mole% of the tnfiuoropropyl side chain with varying levels of VDMO. The films were transparent and fully cured as determined by NIR spectroscopy. A significant decrease in oleic acid uptake occurred with an increase in the concentration of trifluoropropyl side chain. A 95/5 ( -TFP/VDMO) formulation absorbed 0.2% oleic aad, a 95/5 (40-IFP/vDMO) formulation absorbed 1.0% oleic acid and a 95/5 (DP 100 methacrylate end capped polydimethylsiloxane (no fiuoro substitution)/VDMO) formulation absorbed 4% oleic add followmg an overnight soak. The mechanical properties of these films, however, could not be evaluated due to their poor strength. 

Gosh and Mukherjee reported that monochloroacetic, dichloroacetic and trichloroacetic acids readily initiate photopolymerization of methyl methacrylate at 40 °C in visible light when used in the presence of dimethylaniline. The inhibition period decreases with an increase in the number of chlorine substitution of acetic acid. Addition of benzophenone decreases the induction period. They believe that free-radical initiation is a result of a collapse of the exiplex (acid-dimethylaniline) and an electron transfer from the nitrogen to the carbonyl oxygen of the acid. ... 

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