Branched carboxylic acids, vinyl

Vinyl acetate is polymerized in aqueous emulsion and used widely in surface coating and in adhesives. Copolymerized with vinyl esters of branched carboxylic acids and small quantities of acrylic acid, it gives paint latices of excellent performance characteristics. G. C. Vegter found that a coagulum-free latex of very low residual monomer content can be produced from a mixture of an anionic and a nonionic emulsifier according to a specific operating procedure. The freeze/thaw stability of polymeric latices has been investigated by H. Naidus and R. Hanzes. 

Emulsion Copolymerization of Vinyl Esters of Branched Carboxylic Acids with Vinyl Acetate... 

Vinyl acetate is fairly water soluble and somewhat deficient in hydrolytic stability. The incorporation of a vinyl ester of the higher branched carboxylic acids into a copolymer system improves the resistance of the product to hydrolysis. Thus the latex formed in Preparation 5-10 has been used in formulating exterior paints. Copolymers of vinyl acetate with increasing concentrations of vinyl 2-ethylhexanoate (VEH) were prepared by a procedure similar to that of Preparation 5-10, except that the initiator system consisted of terf-butyl hydroperoxide and sodium formaldehyde sulfoxylate, and the buffer was sodium acetate. As the level of VEH increased, the hydrolytic stability of the copolymer increased significantly [169],... 

Because the aldehyde group is an extremely versatile functionality, AH constitutes a useful entree into chiral biologically active compounds such as the nonsteroidal antiinflammatory drug (S)-naproxen (32), commonly called Aleve. Section 9-7-1 highlighted a racemic hydrofomylation that was a key step in the synthesis of ibu-profen. naproxen is quite similar to ibuprofen in structure, but the toxic nature of racemic Naproxen in the body demands that it be synthesized and administered as the much less toxic (S)-enantiomer. Scheme 12.14 shows a possible route to 32, first involving AH of the vinyl naphthalene in the presence of BINAPHOS (34, Fig. 12-6) to create the chiral branched aldehyde and then subsequent oxidative conversion of the aldehyde to the carboxylic acid.83 AH of vinylnaphthalene (33)... 

As noted in Section 6.5.2, the hydrolysis resistance of latex films from emulsion polymers prepared from the vinyl acetate (VA) monomer is marginal for ontdoor use. In Europe and recently in the United States, vinyl versatate (II) (Ri = —CH2CH2CH2CH2CH2CH2CH3 and R2 = R3 = —CH3) has been introduced for use along with vinyl acetate for improved outdoor performance of latex coatings. Vinyl versatate is the vinyl ester of versatic acid, a 10-carbon carboxylic acid of the highly branched structure sometimes called neo ... 

Commercial versions contain several isomers in which Ri, R2, and R3 are alkyl gronps of varying length but with a total of 8 carbon atoms. The mixed carboxylic acid precnrsors of these highly branched esters are collectively called neodecanoic acid [27], and the ester is then called vinyl neodecanoate (VN). The advantage of VA/VN copolymers over other VA copolymers is greater hydrolysis resistance and increased hydrophobicity [27]. These advantages are realized at relatively low cost. Developments such as this are likely to increase the rate of conversion to waterborne systems. 

Saturated fatty acids, such as myristic, palmitic, and stearic acid, have been used as the carboxylic acid component of vinyl esters [56]. In the hydroformylation with a heterogeneous Rh/C catalyst, mainly the branched aldehyde was observed, which in turn was converted into the corresponding alcohols (Scheme 6.97). 

Zhang et al. effected palladium-catalyzed oxidative C3-vinylations of indol-izine-l-carboxylates 136 with various styrenes (Scheme 10.45)."° Use of the bidentate nitrogen ligand bipy was key to formation of the branched a-product regioisomer 137 over the linear P-product. The authors later demonstrated that the same indolizine-l-carboxylates could be C3-acylated with a variety of a,P-unsaturated carboxylic acids via C—H and C—C double bond cleavage under oxidative conditions (138). "... 

The synthesis of branched polyvinyl acetate was based on the same method carboxyl-ended material was transformed to acid chloride with thionyl chloride and condensed with a linear copolymer of vinyl alcohol and vinyl acetate (155, 156). 

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