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Linear and branched zinc(II) xanthates with varying alkyl chain length were synthesized and characterized by 1H NMR, 13C NMR, and IR spectroscopy, as well as elemental analysis. Zinc sulfide as the final decomposition product upon thermal annealing of zinc(II) xanthates was confirmed by XRD analysis. Cure time for epoxy resin composite at various temperatures was analyzed employing zinc(II) xanthates (5 % mass) as latent cure catalysts. XRD investigation of the cured epoxy resin including zinc(II) xanthates upon thermal annealing revealed the presence of ZnS in‐situ in the composite matrix, indicating the in‐situ thermal decomposition of zinc(II) xanthates as probable mechanism for curing. Thermogravimetric analysis was performed to investigate the thermal decomposition temperature trend of zinc(II) xanthates. A parallel trend was observed correlating the thermal decomposition temperature trend of zinc(II) xanthates and the order of curing catalytic efficiency utilizing zinc(II) xanthates. In the case of linear alkylzinc(II) xanthates with an increase in the alkyl chain length, both thermal decomposition temperature and the cure time were enhanced. In contrast, in case of branched alkyl chain zinc(II) xanthates with increasing alkyl chain length show decreasing thermal decomposition temperature as well as cure time.

The latent thermal curing catalyst “Ga(iii) xanthate” for an epoxy resin/phenol composite, and its curing behaviour are reported.

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CO 2 Et N O CO 2 Et N O CO 2 Et N (RR)-Co-salen OH HO N CO 2 Et HO Boc N CO 2 Et HO Boc Boc H H Boc Boc H 5-hydroxypipecolic acid synthesis from intramolecular reaction of epoxy amino acids; enatiomers separated by hydrolase and diastereomeric epoxide separated by Jacobsen's hydrolytic kinetic resolution.ABSTRACT: Diethyl malonate derivatives were used to synthesize racemic 2-amino-5-hexenoic acid. This racemic 2-amino-5-hexenoic acid (homoallylyglycine) derivatives were efficiently resolved aided by chymotrypsin or L-acylase, giving rise to L-and D-enatiomers. These isolated enatiomerically pure amino acids with tert-butoxycarbonyl (Boc) protection were oxidised with 3-chloroperbenzoic acid. The oxidation gave rise to an inseparable diastereomeric epoxides due to newly generated chiral center at C 5 carbon. The isolation of one of the diastereomeric epoxide was possible by selectively converting the remaining diastereomer into a dihydroxyl compound catalysed by Jacobsen's hydrolytic kinetic resolution (HKR).The isolated epoxide was regioselectively attacked by LiBr to give vicinal halohydrin, with bromide attacking on terminal C 6 carbon.Upon (Boc) deprotection of the halohydrin, lead to intramolecular cyclization by attack of free amine at C 6 carbon, generating a single isomer of 5-hydroxypipecolic acid which was effortlessly recovered in good yield after re-protection of the amine with (Boc) group. Similarly the dihydroxyl compound isolated earlier was converted to an halohydrin with iodine at the C 6 carbon. This was feasible by efficient regioselective monotosylation with catalytic (Bu 2 SnO) followed by iodine substitution. This was utilized to synthesize the 5hydroxypipecolic acid derivative in the same described sequence consisting of Boc removal by acid treatment, cyclization, reprotection and purification. Finally the same sequence was repeated with D-isomer and two diastereomers were isolated.