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Reactions of wood components with hydrogen sulfide. VIII. Influence of cation and base catalysts on the reductive thiolation reaction at cellulose‐reducing endgroups
Author(s) -
Procter A. R.
Publication year - 1971
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1971.070150101
Subject(s) - chemistry , catalysis , sodium hydrosulfide , sodium sulfide , inorganic chemistry , cellulose , ammonia , base (topology) , reducing agent , magnesium , hydrogen sulfide , organic chemistry , sulfur , mathematical analysis , mathematics
In the presence of calcium, magnesium, and ammonium ions, the reductive thiolation reaction at cellulose‐reducing endgroups by a hydrogen sulfide–hydrosulfide ion buffer system is more efficient when compared to the sodium base system. The calcium and magnesium base systems show a maximum reaction rate when the buffer pH is 5.9, thus behaving similarly to the previously described sodium base system. In the ammonium base system, however, there is a specific ammonia‐catalyzed reaction with no maximum in the reaction rate over the available pH range. The increased efficiency of the bivalent ion systems is thought to be due to the formation of a salt‐like complex between the cation and an intermediate gem‐dithiol structure in the reductive thiolation reaction scheme. Ammonia enters into the kinetics of the reaction, but the exact mechanism of its action is unclear. Some other nitrogenous bases also catalyze the reductive thiolation. The use of ammonium hydrosulfide to carry out the reductive thiolation reaction is also briefly described.