Chlorophenylalkyl-Substituted Carboxylic Acids and Silanes Designed as Adhesion Promoters

摘要

The six new carboxylic acids of this study feature a terminal p-chlorophenyl substituent, a polymethylene spacer, and either one or two carboxyl groups. The carboxyl groups may be replaced by -SiCl3 or -Si(OC2H5)3 groups. Such structures are designed to promote adhesion between a solid substrate and an organic resin by forming a monolayer strongly attached to the substrate and exposing a chlorophenyl outer surface which is easily wet by the resin. Multistep syntheses were carried out for the preparation of monocarboxylic acids p-ClC6H4(CH2)n-1CO2H, where n is 12, 14, 18, and 20, via Friedel-Crafts reactions and Wolff-Kishner reductions. Some also used a subsequent LiAlH4 reduction. Succinic and glutaric acids substituted in the alpha position by a p-ClC6H4(CH2)12-substituent were prepared through malonic ester syntheses. The acids were characterized by melting points, neutralization equivalents, and elemental assays. NMR spectra showed that the chlorine substitution is at least 95% para. Gas-liquid chromatography was used to assess the purity of both intermediates and products; most of the acids had purities exceeding 97.5%. Principal impurities were the unchlorinated analogs and lower homologs. The Friedel-Crafts method was employed to prepare p-ClC6H4(CH1)2SiCl3; this compound and its trimethoxy and triethoxy analogs were characterized by conventional criteria. (Author)