The oxidation of 2-alkoxy-3,6-di-tert-butylphenols. The reversible dimerization of 2-alkoxy-3,6-di-tert-butylphenoxy radicals
摘要:
The oxidation of 2-alkoxy-3,6-di-tert-butylphenols has been studied. It was found that 2-RO-3,6-di-tert-butylphenoxy radicals (R = Et, Pr, Ph) undergo dimerization by C-O coupling. The X-ray structure of 2-ethoxy-3,6-di-tert-butylphenoxy dimer has been determined. Radical dimers dissociate reversibly in solution to give two phenoxy radicals at 200-350 K. By using EPR spectroscopy the equilibrium concentration of the phenoxy radicals, equilibrium constants and AH and AS of dissociation have been determined. (c) 2005 Elsevier Ltd. All rights reserved.
取代基中的反应的效果3,6-二-叔丁基- о苯醌与有机锌和organocadmium化合物,导致三种类型的产品:3-烷基-6-叔丁基- о -benzoquinones,4-烷基-3,6-二-叔丁基- о -benzoquinones和2-烷氧基- (或2-苯氧基)-3,6-二-叔-butylphenols。相关分析提供了证据,表明第一类和第二类产物是通过亲核的1,2-和1,4-加成形成的,而取代的苯酚则是由单电子转移产生的。
interaction between organometallic R2M and carbonyl compounds. The reaction of organometalliccompounds R2M with o-quinone, where R = Ph, Me, Et, Pr, 1Pr or tBu and M ≡ Zn, Cd, and Al, proceeds in two ways: (1) the single-electron oxidation of the organometalliccompound by o-quinone, resulting in derivatives of alkyl(phenyl)oxyphenols; (2) the polar 1,2 and 1,4 addition of organometallic molecules to o-quinone