Patent GB-444631-A (GB)
Title: Improvements in the manufacture and production of 2.3-dihydroindoles
IPC: C07D209/08
Filed: 1934-09-15
Abstract: 2 : 3 Dihydroindoles are made by subjecting indoles to the action of hydrogen at elevated temperatures in the presence of catalysts comprising copper.  The process can be advantageously carried out at increased pressures, particularly in the liquid phase, when it is sometimes preferable to use solvents, and the process can be made continuous.  Gases containing or agents producing hydrogen may be used instead of the gas itself, the pressure of which can be raised to over 200 atmospheres, the temperatures being between 150--250 DEG C., without hydrogenating the benzene ring.  Derivatives of indole may be used instead of indole itself.  Catalysts containing copper are prepared by the usual methods, and by the decomposition of a copper-magnesium alloy with steam, giving a mixture of copper and magnesium oxide.  By using compounds such as copper formate, which leave behind finely-divided copper, separate preparation of the catalyst is avoided.  Small amounts of other metals may be incorporated with the copper.  In examples: (1) 2-methylindole is heated in a stirring autoclave to 220 DEG  C. under a hydrogen pressure of 200 atmospheres with copper oxide.  The product is fractionally distilled to separate the 2 : 3 dihydro-2 methylindole; (2) 2-methylindole is heated to 180 DEG  C. under the conditions of example 1 with a catalyst comprising copper, aluminium and barium; (3) 2-methylindole is treated as in example 2, using a catalyst comprising copper and manganese; (4) indole is treated as in example 2 at 170 DEG  C.; (5) 2 : 5 dimethylindole is treated as in example 2 at 170 DEG  C. and 250 atmospheres pressure; (6) 1 : 2 dimethylindole is treated as in example 2; (7) 2 : 6 dimethylindole; and (8) 2 methyl-6 methoxy indole are treated as in example 2; (9) 2 phenylindole is dissolved in methanol and treated at 150 DEG  C. as in example 2.  Specification 326,523, [Class 2 (iii)], is referred to.ALSO:2 : 3 Dihydroindoles are made by subjecting indoles to the action of hydrogen at elevated temperatures in the presence of catalysts comprising copper.  The process can be advantageously carried out at increased pressures, particularly in the liquid phase, when it is sometimes preferable to use solvents, and the process can be made continuous.  Gases containing or agents producing hydrogen may be used instead of the gas itself, the pressure of which can be raised to over 200 atmospheres, the temperatures being between 150--250 DEG  C., without hydrogenating the benzene ring. Derivatives of indole may be used instead of indole itself. Catalysts containing copper are prepared by the usual methods, and by the decomposition of a copper-magnesium alloy with steam, giving a mixture of copper and magnesium oxide.  By using compounds such as copper formate, which leave behind finely-divided copper, separate preparation of the catalyst is avoided.  Small amounts of other metals may be incorporated with the copper.  In examples: (1) 2-methylindole is heated in a stirring autoclave to 220 DEG  C. under a hydrogen pressure of 200 atmospheres with copper oxide.  The product is fractionally distilled to separate the 2 : 3 dihydro-2 methyl-indole.  (2) 2-methylindole is heated to 180 DEG  C. under the conditions of example 1 with a catalyst comprising copper, aluminium and barium. (3) 2-methylindole is treated as in example 2, using a catalyst comprising copper and manganese (4) Indole is treated as in example 2 at 170 DEG  C. (5) 2-5 dimethylindole is treated as in example 2 at 170 DEG  C. and 250 atmospheres pressure.  (6) 1 : 2 dimethylindole is treated as in example 2 (7) 2 : 6 dimethylindole and (8) 2 methyl-6 methoxy indole are treated as in example 2 (9) 2 phenylindole is dissolved in methonol and treated at 150 DEG  C. as in example 2 Specification 326,523, [Class 1 (i)], is referred to.