1-Phenyl-1-propanone → 1H-Inden-1-one, 2-methyl-

Participants

Reaction Conditions

Reaction Steps

A mixture of propiophenone (30 g, 223.6 mmol) hexamethylenetetramine (HMTA) (43.8 g, 313 mmol) and acetic anhydride (41 g, 402 mmol) was heated at 80° C. for 4 hours under a nitrogen atmosphere. The reaction mixture was cooled to 30° C. and quenched into a stirred mixture of methylene chloride (200 ml) and sodium hydroxide (200 of 2N solution). The organic layer was separated and washed with aqueous HCl (100 ml of 1N solution). The methylene chloride solution containing the product, 2-methyl-1-phenyl-prop-2-en-1-one was azeotropically dried by distilling CH2Cl2 to approximately 50 ml volume and was directly used in the next step without any further operation. The CH2Cl2 solution was added to concentrated H2SO4 (130 ml) at such a rate that the reaction temperature was maintained between 50°-60° C. The CH2Cl2 was removed by distillation and nitrogen sweep as soon as it was added. The reaction mixture was stirred at 50°-60° C. for one hour, cooled to 20° C. and quenched into a stirred mixture of methylene chloride (200 ml) and water (200 g). After separating the aqueous layer, the organic layer was concentrated in the rotary evaporator to produce 121 g (82%) of 2-methyl-inden-1-one (Example 1, Table 1).

Provenance & Evidence