Carboxymethy lation

A DS of up to 1.0 is obtained in one step by applying optimised reaction conditions 3.8 M aqueous NaOH, reaction temperature of 60 °C for 90 min in tert-butanol/water or isopropanol/water 85 15 (v/v) mixtures (Table 12) [219]. The DS of CMD can be increased by repeated carboxymethy-lations. CMD with DS 1.5 was realised by two-step carboxymethylation. Under optimal conditions, the applied NaOH solution was 3.8 M. The DS value is decreased with lower NaOH concentrations because of incomplete activation of the hydroxyl groups, and also with higher NaOH concentrations due to increasing side reactions of MCA with NaOH forming glycolic acid [280]. 

The type I deiodinase of liver and kidney is inactivated by different SH-selective reagents. In particular, it shows an extremely high susceptibility to carboxymethy-lation by iodoacetate and a somewhat lesser sensitivity for iodoacetamide and bro-moacetate [42]. In comparison, A-alkylmaleimides are only inhibitory at high concentrations (> 0.1 mM) [42]. Enzyme inactivation by iodoacetate follows pseudo... 

Parish, C.A., and Rando, R.R. (1994). Functional significance of G protein carboxymethy-lation. Biochemistry 33 9986-9991. 

This reaction profile, also called carbonylation, governs the reactivity of Pd-carbonyl complexes. Anionic M[Pd(CO)l3], for instance, catalyzes the reductive carbonylation of esters.f On the other hand, Pd(CO)(PPh3)3 was reported to catalyze the carboxymethy-lation of organic halides and the cyclocarbonylation of cinnamyl halides.f " However, the Pd-CO complexes are most often generated in situ from preformed alkyl -palladium complexes and CO under stoichiometric or catalytic conditions, for example, in the copolymerization of alkenes and CO. Decarbonylation reactions also involve the intermediacy of Pd-CO complexes. In this case, migratory deinsertion (Sect, n.3.1), that is, the microscopic reversal of the migratory insertion, takes place. 

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