ジアリールメタン類に関する研究(第2報)

1,2,4-トリメチルベンゼンとフォルムアルデヒドとの縮合反応生成物の接触水素化分解

抄録

The catalytic hydrocracking of bis (trimethylphenyl)-methane (BTMPM), condensation products of 1, 2, 4-trimethylbenzene (1, 2, 4-TMB) with formaldehyde, was studied with a fixed bed type reactor under atmospheric pressure. The CoO-MoO₃-Al₂O₃ catalyst pretreated with hydrogen or hydrogen and hydrogen sulfide mixture was used. Benzene solution of recrystallized BTMPM was used as the feed. Reaction conditions covered the ranges of temperature from 340 to 500°C, molar ratio (H₂/H. C.) from 1.5 to 8.5 and LHSV from 2 to 5hr^-1. Results were summarised as follows.
1) The hydrocracking of BTMPM occurred at a relatively low temperature such as 340°C, and the conversion was 100% under the above operating variables. The selectivity of tetramethylbenzenes (TeMB) was 92-95%, and the purity of 1, 2, 4, 5-TeMB in TeMB was 98%, while the selectivity of TMB was 105%. This fact suggested that hydrodemethylation of BTMPM and/or TeMB occurred slightly. The isomerization of 1, 2, 4, 5-TeMB was negligible under the above conditions.
2) The activity change with the reaction time of the catalyst pretreated with hydrogen was relatively small. The deactivated catalyst was regenerated by calcination at 430-550°C in the presence of air, and following treatment with hydrogen.
3) It was estimated that the crude condensation products of 1, 2, 4-TMB with formaldehyde are composed of 2, 4, 5, 2', 4', 5'-, 2, 3, 6, 2', 4', 5'- and 2, 3, 5, 2', 4', 5'-hexamethyldiphenylmethane.
In the catalytic hydrocracking of unsymmetrical diarylmethane, two different sites of carbon-carbon cleavage are possible. It was estimated that these two cleavage don't proceed with equal probability, but one cleavage occurs in preference to another.