Synthesis polycarboxylates

Casnati, A. Baldini, L. Sansone, F. Ungaro, R. Armaroli, N. Pompei, D. Barigelletti, F. Synthesis, complexation and photophysics in protic solvents of lanthanide complexes of novel calix[4]arene polycarboxylic-2,2,-bipyridine mixed ligands. Supramol. Chem. 2002,14(2-3), 281-289. 

Catalysts are also required in many stepwise polymerizations. For example, reaction of polycarboxylic acids and polyols (Reaction 7) is catalyzed by acids ester interchange, by metal compounds such as titanium alkoxides. On the other hand, polyurea synthesis (Reaction 6) generally does not require a catalyst. Metallic compounds are also useful in oxidative polymerization of phenols to give poly(phenylene oxides), illustrated in Reaction 14. 

Several investigations have been carried out to modify starch catalytically with the aim of obtaining specific hydrophilic properties. For example, selective oxidation of the hydroxymethyl groups of starch molecules leads to polycarboxylic adds, which can be used as adsorbers in diapers (nappies). A suitable catalyst for the synthesis of... 

Other interesting targets for applications of catalytic oxidation of sugars may include the synthesis of free gluconic acid [23] and antiscaling polycarboxylated sugar [26-28]. 

Soon after the introduction of convergent dendrimer synthesis, " hemispherical, aryl-ester-coated, benzyl ether-based dendrons were reported. Attachment to a divalent core and conversion to the polycarboxylate 25 (Fig. 5) yielded dendriiners that facilitated a 200-fold increase in pyrene (26) solubility in water eompared with that of pure water without the dendrimer. Notably, use of sodium dodecyl sulfate (SDS above cmc 9 X 10 M) for pyrene encapsulation resulted in only an 100-fold enhancement. 

A.D. Wilson, J.W McLean, Glass-ionomer Cement, Quintessence Publishing, Chicago, 1988. S. Crisp, B.E. Kent, B.G. Lewis, A.J. Ferner, A.D. Wilson, Glass ionomer cement formulations. n. The synthesis of novel polycarboxylic acids, J. Dent. Res. 59 (1980) 1055-1063. 

Another important group are the polyamide imides and polyimides. The substitution of tricarboxylic acid anhydride for dicarboxylic acids during synthesis results in thermally more stable polyamide imides. The polycondensation reaction proceeds in two steps, with the solution of the intermediate polycarboxylic acid used in applications where the final product can be generated by a thermal or baking process. Uses include heat-resistant wire and cable coatings. The basic synthesis of polyamide imides is as follows ... 

Other grafts to natural materials are exemplified by Dordick s work [173] in which he produced polyesters from sugars and polycarboxylates by enzyme catalysis of the condensation polymerization. These polymers and the method of synthesis may well be the future of renewable resource chemistry. 

Polycarboxylate Crown Ethers Synthesis, Complexation, Applications... 

Abstract. Crown ethers derived from tartaric acid present a number of interesting features as receptor frameworks and offer a possibility of enhanced metal cation binding due to favorable electrostatic interactions. The synthesis of polycarboxylate crown ethers from tartaric acid is achieved by simple Williamson ether synthesis using thallous ethoxide or sodium hydride as base. Stability constants for the complexation of alkali metal and alkaline earth cations were determined by potentiometric titration. Complexation is dominated by electrostatic interactions but cooperative coordination of the cation by both the crown ether and a carboxylate group is essential to complex stability. Complexes are stable to pH 3 and the ligands can be used as simultaneous proton and metal ion buffers. The low extractibility of the complexes was applied in a membrane transport system which is a formal model of primary active transport. 

The central reaction is, of course, the Williamson ether synthesis. Early reports on the preparation of tartaric acid ethers [11], suggested that the base thallous ethoxide, (TlOEt), was essential to avoid epimerization of the chiral centers. The first syntheses thus utilized this base in dimethyformamide (DMF), and oligo-ethylenglycol diiodides for the preparation of di- and tetra-carboxylate crown ethers [4, 12]. More recently, we found that by strict control of stoichiometry, sodium hydride could be used successfully to displace tosylate without loss of chiral integrity [5]. Scheme 1 shows a recent synthesis of an 18-crown-6 hexaacid from three units of (H-)tartaric acid [13]. This route illustrates all the key features in the syntheses of polycarboxylate crown ethers. 

As suggested by the Tamiflu example shown above (cf., diazide 34), the Curtius rearrangement opens the possibility for polyamine synthesis from polycarboxylic acids. When two carboxyl groups are attached to the same carbon, hydrolysis of the rearrangement product provides aldehydes or ketones. Tricarboxylic acid hydrazide 42, for example, served as the starting... 

Illumination of suspensions of P. shermanii by light (2000-2500 lux) for 48-72 h sharply decreases the production of vitamin B and its corrinoid precursors, cobyrinic acid and its amides, and is accompanied by a considerable increase in porphyrin synthesis (mainly coproporphyrins III) (Yeliseev and Bykhovsky, 1990). The amidation of cobyrinic acids is an important regulatory step of the vitamin Bn biosynthesis (Yeliseev et al., 1988). When methylation is impaired, polycarboxylic corrinoids accumulate, inhibiting steps that precede the synthesis of corrinoids, including the methylation of UPB III (Bykhovsky and Zaitseva, 1989). 

Alkyd resins completely based on renewable resources have been the subject of a few studies. EP 0741 175 A2 to Hoechst describes waterborne alkyd emulsions based on renewable resources. The patent describes the use of sorbitol (easily derived from starch) as the polyhydric alcohol part and succinic acid anhydride as the polycarboxylic acid part. Hajek described the use of sorbitol and xylitol in alkyd resin synthesis, whereas Bagchi et al. described the partial replacement of conventional polyols, i.e., glycerol and pentaerythritol, by sorbitol. 

Schwamborn, M. (1998) Chemical Synthesis of polyaspartates a biodegradable alternative to currently used polycarboxylate homo- and copolymers. Polym. Degrad. Stab., 59 (1), 39-45. 

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