Carboxylic acid generation

Anionic polymerization techniques were also critical for the synthesis of a model cyclic triblock terpolymer [cyclic(S-fo-I-fr-MMA)] [196]. The linear cctw-amino acid precursor S-fr-I-fr-MMA was synthesized by the sequential anionic polymerization of St, I and MMA with 2,2,5,5-tetramethyl-l-(3-lithiopropyl)-l-aza-2,5-disilacyclopentane as the initiator and amine generator, and 4-bromo-l,l,l-trimethoxybutane as a terminator and carboxylic acid generator. Characterization studies of the intermediate materials as well as of the final cyclic terpolymer revealed high molecular and compositional homogeneity. Additional proof for the formation of the cyclic structure was provided by the lower intrinsic viscosity found for the cyclic terpolymer compared to that of the precursor. 

Where acetic is the starting acid (eq. 1), homologation selectively yields the corresponding C3+ aliphatic carboxylic acids. Since acetic acid is itself a "syngas" chemical derived from methanol via carbonylation (2,3), this means the higher MW carboxylic acids generated by this technique could also be built exclusively from C0/H2 and would thereby be in-depent of any petroleum-derived coreactant. 

The main drawback to this reaction is the toxicity of diazomethane and some of its precursors. One possible alternative is the use of alkyltriazenes as reactive alkylating agents.52 Alkyltriazenes are readily prepared from primary amines and aryldiazonium salts.53 The triazenes, on being protonated by the carboxylic acid, generate a reactive alkylating agent that is equivalent, if not identical, to the alkyldiazonium ions generated from diazoalkanes. 

Anodic oxidation of a carboxylic acid generates a carbenium ion at the a-carbon. This contrapolarization enables a facile fragmentation of y-keto acids [255],... 

Carboxylic acids generated in acylation reactions have been effectively sequestered by ion pair formation with Amberlite IRA-68 ion exchange resin.29 3 Similarly, 4-nitrophenoxide formed in acylations of 4-nitrophenyl esters has been captured by anion exchange with the quaternary ammonium hydroxide resin 12.31 An exception to ion pair-mediated sequestration of byproducts is the polyamine functionalized resin 3 that was shown to covalently sequester the (3-methoxy enone hydrolysis byproduct from Danishefsky s diene via imine formation.23... 

The presence of the carboxylic group will cause further breakdown. The removal of this group by the reaction with carbodiimide helps stop continued breakdown of the polyester. Carbodiimides are made from isocyanates. Their reaction with the carboxylic acid generated in the hydrolysis is illustrated in Figure 2.42. 

Succinic acids. The dianion salt of carboxylic acids, generated with LDA and freed from diisopropylamine, on reaction with L ouples to form derivatives of succinic acid. This coupling of 3-phenylpropionic acid dianion results largely in the r/Z-isomer (equation 1). 

The mechanism of stabilization of polyesters by carbodiimides is based on their rapid reaction with carboxylic acids, generated in the hydrolysis of polyesters. Carboxylic acids are catalysts for further hydrolysis of the polyesters. 

To a considerable extent, pyrolysis of nylons made from a diamine and a dibasic carboxylic acid generate the same type of compounds as poly(amino acids). It includes... 

Because the C-NMR analyses showed that gluconic acid was the only carboxylic acid generated in the reaction medium, the yields in gluconic acid (YglU/ %) were calculated directly from the NaOH consumption. The main side product is fructose due to isomerisation in the presence of oxygen and appears at an extent between 2.6 and 4.6 % yield when Yglu is larger than 10 %. 

The reaction of vinyl chloroformate with the sodium salt of a carboxylic acid generates the corresponding vinyl ester in good yields in most cases (43) [224]. This method constitutes a very good laboratory synthesis of vinyl esters. 

Fatty acids (Section 17.8) Long-chain carboxylic acids generated by the hydrolysis of fats. Fatty acids are derived from acetic acid and always contain an even number of carbons. 

Barton [58] has shown that the irradiation of thiohydroxamic esters of perfiuoro-carboxylic acids generates Rp radicals which in the presence of olefins give addition products. However, in the absence of radical traps they attack the sulfur to yield, for example, S-trifluoromethyl derivatives of pyridine (Scheme 26). 

Carboxylic acids generated by source rocks are strongly dissociated. 

In general, the evolution of the oxidation was followed by the sodium hydroxide consumed to neutralize the carboxylic acids generated in C6 carbons (conductometric titration). The increase of NaOCl concentration up to 2 eq involved an increase in the degree of oxidation (Do) of cellulose samples. 

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