Thermolysis of Model Compounds for Coal. 2. Condensation and Hydrogen Transfer during Thermolysis of Naphthols

Article abstract of DOI:10.1021/jo00139a001

The dominant initial products from thermolysis of 1-naphthol in the liquid phase at 400 deg C are 2,2'-binaphthalene-1,1'-diol (2) and 1-tetralone (6).As reaction proceeds, binaphthol 2 undergoes rapid cyclization to dinaphtho<1,2-b:2',1'-d>furan (1), while ketone 6 is more slowly converted ultimately to naphthalene (8).The initial rate of this ring coupling and hydrogen-transfer reaction shows an apparent kinetic order of ca 2.5 in m-terphenyl diluent.In benzophenone solvent, formation of coupled binaphthol 2 is accelerated, but reduced product 6 is replaced by diphenylmethane.Thermolysis of 2-naphthol behaves similarly except that coupling occurs both between C-1 and C-1' to give dinaphtho<2,1-b:1',2'-d>furan (3), preceded by 1,1'-binaphthalene-2,2'-diol (4), and between C-1 and C-3' to give dinaphtho(2,1-b:2',3'-d>furan (5).The major reduction product is 2-tetralone (14).The ratio of (3 + 4)/5 decreases with increasing reaction time.Mechanistic hypotheses for this characteristic thermal behavior of phenols are explored.The significance of the reactions involved for conversion processes for coal, which contains significant phenolic functionality, is discussed.