Ky. Wang et al., MECHANISM STUDY OF SUGAR AND SUGAR ALCOHOL HYDROGENOLYSIS USING 1,3-DIOL MODEL COMPOUNDS, Industrial & engineering chemistry research, 34(11), 1995, pp. 3766-3770
Knowledge of the bond cleavage mechanism governing sugar and sugar alc
ohol hydrogenolysis is important-to control of the selectivity of suga
r and sugar alcohol hydrogenolysis. Previous work by others has result
ed in the suggestion of a variety of mechanisms to explain the C-C cle
avage in sugar and sugar alcohol hydrogenolysis, and has not provided
any definitive evidence to elucidate either the C-C or C-O cleavage me
chanism. In this work, we present a mechanism study carried out using
1,3-diol model compounds. Our experimental results indicate that cleav
age of the C-C and C-O bonds in hydrogenolysis is through retro-aldoli
zation and dehydration of a beta-hydroxyl carbonyl, respectively. The
structure of this beta-hydroxyl carbonyl is already contained in an op
en-chain sugar molecule, and is generated from the sugar alcohol molec
ule by dehydrogenation. The intermediates from both C-C and C-O cleava
ge are subsequently hydrogenated to yield alcohols or polyols. This me
chanism of sugar and sugar alcohol hydrogenolysis provides us a good b
ackground to understand factors that control the selectivity in sugar
and sugar alcohol hydrogenolysis. Based on this understanding, a ratio
nal approach to control of the selectivity of sugar and sugar alcohol
hydrogenolysis may be developed.