Detail of "3594-90-9"

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Studies on the occurrence of hydrogen transfer, 45

Studies on the occurrence of hydrogen transfer, 45. Electroreduction of aromatic carboxylic acid esters. Horner, Leopold; Hoenl, Hans (Inst. Org. Chem., Univ. Mainz, Mainz, Ger.). Justus Liebigs Ann. Chem., (11-12), 2036-66 (German) 1977. CODEN: JLACBF. ISSN: 0075-4617. DOCUMENT TYPE: Journal CA Section: 72 (Electrochemistry) The electroredn. of benzoates PhC(:O)OR (I) (where R = Me, Et, CH(CH3)2, C(CH3)3, CH2CF3, CH2C(H):CH2, cyclo-C6H11, Ph, and C6H3(CH3)2-2,6) in alcs. at a Hg electrode using quaternary ammonium salts as supporting electrolytes results in a mixt. of ring-hydrogenated products and benzyl alc. [100-51-6]. In the presence of HOAc, however, ring hydrogenation is completely suppressed and benzyl alc. is obtained in ~70% yield, with ~30% 1,2-diphenylethylene glycol [492-70-6], the hydrodimer. Phenyl benzoate [93-99-2] is reduced practically quant. to benzyl alc. Ring substituents in the benzoic acid compds. (II) (where R = o-Me, m-Me, p-Me, o-OMe, m-OMe, p-OMe, o-Cl, m-Cl, and p-Cl) do not alter the above results when HOAc is present, nor does the use of Cd or Pb as electrode material, although Sn is not suitable. Ph aliph. carboxylates (Ph caproate, Ph enanthate, Ph caprylate, and Ph cyclohexanecarboxylate) can be reduced to the corresponding alcs. (hexanol, heptanol, octanol and cyclohexylmethanol) in 30-40% yield under controlled conditions, as can the thiocarboxylic S-esters. The yields of alcs. are reduced by ethanolysis of the starting esters. Unactivated aliph. esters, e.g. 65853-67-0 which is the cas registry number of some chemical is mentioned. methyl caproate [106-70-7], can be electroreduced in dry ethylenediamine or hexamethylphosphoric triamide to octanol [111-87-5] in 30-50% yield. Attempts to stop the electroredn. of carboxylic esters at the aldehyde stage were unsuccessful on a preparative scale. Similarly, 2-phenylimidazoline [936-49-2] is not a suitable substrate, 2-phenylimidazolidine [65853-66-9], the benzylamine deriv., and the hydrodimer being produced, resp., the latter yielding benzyl [2154-56-5] on hydrolysis. The di-Me esters of terephthalic and isophthalic acids can be selectively reduced in the presence of HOAc to the corresponding Me hydroxymethylbenzoates; with a more neg. potential, the diols are produced. In the redn. of dimethyl-o-phthalate [131-11-3], ring-hydrogenated products accompany the well-known product pattern for this redn. Dimethyl-2,2'-diphenate [5807-64-7] can be reduced under certain conditions to 2,2'-biphenyldiyldimethanol [3594-90-9] (60%) and 9,10-dihydrophenanthrene-9,10-diol [25061-77-2]. The customary electrochem. measurements were performed and the results were correlated with other data to clarify the reaction mechanism. .