Methyl radicals reaction with propionic acid

Electrolysis of salts of fatty acids gives free radicals which are capable of reacting with added substrates. For instance, when water-free potassium acetate is electrolyzed in the presence of polymerizing substances (e.g., styrene) methyl groups are incorporated as end groups into the polymer. Goldschmidt et ai. analyzed the products formed in the electrolysis of potassium propionate in propionic acid and showed that they could be accounted for by the following reaction sequence ... 

Type iii-b This reaction leads to products (67). The electrochemical oxidation of the sodium salts of acetic, propionic, and isovaleric acids in the presence of ethylenic compounds bearing electron-withdrawing substituents gives 1,2-dialkylated adducts as the main products. A methyl radical generated from an acetate ion reacts with diethyl fumarate to give diethyl 2,3-dimethylsuccinate in 80% yield [106]. 

The polar effect was at first invoked to explain various directive effects observed in aliphatic systems. Methyl radicals attack propionic acid preferentially at the a-position, ka/kp = 7.8 (per hydrogen), whereas chlorine " prefers to attack at the /3-position, ka/kp = 0.03 (per hydrogen). In an investigation of f-butyl derivatives, a semiquanti-tative relationship was observed between the relative reactivity and the polar effect of the substituents, as evidenced by the pK, of the corresponding acid. In the case of meta- and / ara-substituted toluenes, it has been observed that a very small directive effect exists for some atoms or radicals. When treated by the Hammett relation it is observed that p = —0.1 for H , CeHs , P-CH3C6H4 and CHs . On the contrary, numerous radicals with an appreciable electron affinity show a pronounced polar effect in the reaction with the toluenes. Compilation of Hammett reaction constants and the type of substituent... 

This intricate behaviour was reflected in the competitive carbonylation of the methyl and ethyl radicals when EtI + MeOH and Mel + EtOH mixtures were reacted. Ethyl acetate but also trace methyl acetate were produced. No ethyl propionate was detected on the one hand and essentially methyl acetate and lower amounts of propionic acid, methyl propionate and ethyl acetate were formed (25) using rhodium zeolites indicating that various exchange reactions were proceeding with high enough rates so as to result in a different effective feed composition. These side reactions reveal the importance of the polarity of the medium as well as the nature of the transition metal. 

It is shown that tert-butyl ester 3-(3, 5 -fert.butyl-4 -hydroxyphenyl)-propionic acid possesses anomalously high antioxidative efficacy in radical reaction in the conditions of the initiated oxidation of wo-propyl benzene with an inhibition constant = 3 x 10 1-mol -s and number of stopping of chain f = 5. On the basis of results of quantum-chemical calculations enthalpies H°), entropies S°) and energy of a cleavage of communications OH-bond of tert.butyl and methyl ester 3-(3, 5 -di-tert. butyl-4 -hydroxyphenyl)-propionic acid are calculated energy of formation (-E°). 

In general, the PET decarboxylation of carboxylic acids exhibits low product selectivity, due to the subsequent radical coupling in solution however, the PET reaction between potassium propionate and the methyl ester of N-methyltrimellitic acid imide is highly regioselective to the para-addition product. This contrasts with other intramolecular and intermolecular PET reactions of quinolinic acid imides, which do not show a high degree of regioselectivity (Scheme S)." ... 

Concurrently, the hydroperoxide may be converted to methyl ethyl ketone (MEK). If the initial radical attack is at the primary rather than the secondary carbon, the process makes propionic and formic acids. Reaction conditions can be changed to produce more MEK at the expense of some acetic acid. The maximum acetic acid/MEK ratio is 6.5-7 on a weight basis. If ethyl acetate is also formed, the ratio can go down to acetic acid/(ethyl acetate + MEK) of 3.6-4, with MEK being about 55 percent of the byproduct. 

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