The general procedure for the synthesis of 2-methyl-5-amino-2H-tetrazole from compound (CAS: 949089-83-2) is as follows:
1. To a clean stainless steel reactor was added palladium hydroxide (1 g), N,N-dibenzyl-2-methyl-2H-tetrazol-5-amine (10 g from Step C) and ethanol (100 mL).
2. Hydrogen was introduced into the reaction system, heated to 50 °C, and the hydrogen pressure was maintained at 50 psi for 16 hours.
3. When hydrogen absorption ceased, replace the hydrogen in the reaction system with nitrogen and filter to remove the catalyst.
4. The catalyst pad was washed with 25 mL of ethanol and the washings were combined with the filtrate and concentrated to give 2.7 g of an off-white solid product (73% yield).
5. Prepare an analytical sample by recrystallization from isopropanol.
Product characterization data:
1H NMR (400MHz, DMSO-d6) δ 5.94 (s, 2H), 4.03 (s, 3H); 13C NMR (400MHz, DMSO-d6) δ 167.8, 40.52. Calculated values for elemental analysis (measured values): C, 68.79 (68.54); H, 6.13 (6.41); N, 25.07 ( 24.83).
Alternative method (using a mixture of regional isomers):
1. To a clean stainless steel reactor was added palladium hydroxide (1.4 g), a 9:1 mixture of N,N-dibenzyl-2-methyl-2H-tetrazol-5-amine with N,N-dibenzyl-1-methyl-1H-tetrazol-5-amine (14 g, from Step C) and ethanol (140 mL).
2. Hydrogen was introduced into the reaction system, heated to 50°C, and hydrogen pressure was maintained at 50 psi for 16 hours.
3. When hydrogen absorption ceased, replace the hydrogen in the reaction system with nitrogen and filter to remove the catalyst.
4. The catalyst pad was washed with 50 mL of ethanol and the washings were combined with the filtrate and concentrated to give an off-white solid product of 5.1 g (as a stoichiometric mixture of 1-methyl-2H-tetrazol-5-amine and 2-methyl-2H-tetrazol-5-amine).
5. The crude product was dissolved in dichloromethane and filtered to remove unwanted isomers.
6. Displacement of the dichloromethane layer by isopropanol gave 3.8 g of the target product.
