Phenylhydrazine → 2,2'-bithiophene-5-carboxaldehyde N-phenylhydrazone

Participants

Reaction Steps

A mixture of 2,2′-bithiophene-5-carboxaldehyde (5.0 g, 0.0257 mole, obtained from TCI Europe nv, Boerenveldseweg 6, 2070 Zwijndrecht) and 10 ml of 2-propanol was added to a 100 ml, 2 neck round bottom flask equipped with a reflux condenser and a mechanical stirrer. Heat was applied until all 2,2′-bithiophene-5-carboxaldehyde entered into solution. After all 2,2′-bithiophene-5-carboxaldehyde was dissolved, a hot solution of phenylhydrazine (3.05 g, 2.78 ml, 0.0309 mole, obtained from Aldrich) in 3 ml of 2-propanol was added to the 2,2′-bithiophene-5-carboxaldehyde solution. After the reaction mixture was refluxed for 6 hours, the mixture was cooled to room temperature. The crystals formed were filtered off, and then washed with a mixture of 2-propanol and hexane in 1:1 ratio by volume. The yield of the product, 2,2′-bithiophene-5-carboxaldehyde N-phenylhydrazone, was 6.95 g (94.9%). The product was recrystallized from 2-propanol and dried at 60° C. in a vacuum oven for 6 hours. The melting point of the product was found to be 156-158° C. An infrared absorption spectrum of the product was characterized by the following absorption wave numbers (KBr window, cm−1): 3306 (NH); 3104, 3061 (CHaromatic); 1599 (C═C, C—N). A 1H-NMR spectrum (300 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 7.77 (s, 1H, CH═N); 7.30-7.00 (m, 9H, Ph, Ht, NH); 6.95 (d, 1H, Ht); 6.87 (t, 1H, 4-H Ph). An elemental analysis yielded the following results in weight percent: C, 63.50; H, 4.16; N, 9.97, which compares with the following calculated elemental weight percent for a compound with the formula C15H12N2S2: C, 63.35; H, 4.25; N, 9.85.

Provenance & Evidence