Applications of Pyridyl Thiourea_Industrial Additives

Background and Overview

Pyridylthiourea can be used as a pharmaceutical synthesis intermediate. If ppyridylthiourea is inhaled, move the patient to fresh air; if the skin comes in contact, take off contaminated clothing, rinse the skin thoroughly with soap and water, and seek medical treatment if you feel unwell; if the eye contacts, seek medical attention. Separate eyelids, rinse with running water or saline, and seek medical attention immediately; if ingested, rinse mouth immediately, do not induce vomiting, and seek medical attention immediately.

Application structure of p-pyridylthiourea

Application and preparation of p-pyridylthiourea

Pyridylthiourea was prepared as follows: 1,1-thiocarbonyldiimidazole (29.4g, 0.1 sodium bicarbonate 6mol) was added to 4-aminopyridine (14.1g, 0.15mol) in anhydrous tetrahydrofuran ( 600 mL) solution, and the resulting mixture was stirred for 17 hours. The solvent was removed under reduced pressure and the resulting solid was suspended in a mixture of dichloromethane and water. The undissolved solid was filtered and washed with acetone to obtain the solid product (8.98 g). Gaseous ammonia was bubbled through a solution of the resulting solid product (8.50 g, 0.06 mol) in anhydrous tetrahydrofuran (250 mL) for 20 minutes. The ammonia flow was stopped and the mixture was stirred for 17 hours, during which time a precipitate formed in the reaction. Filtration and drying of the solid under vacuum gave the desired thiourea product, p-pyridylthiourea (5.1 g).

Applications of pyridylthiourea

p-Pyridylthiourea can be used as a pharmaceutical synthesis intermediate, such as N-pyridin-4-yl-piperazine-1-carboxamidine trifluoroacetate. The specific steps are: p-pyridylthiourea (3.90 g, 26 mmol), a mixture of N-tert-butoxycarbonyl-piperazine (4.84 g, 26 mmol) and 1,3-dicyclohexylcarbodiimide (5.90 g, 28 mmol) in dioxane (105 mL) was refluxed . Nitrogen for 48 hours. The solvent was removed under reduced pressure and the residue was sonicated in toluene and filtered. The residue was concentrated to approximately one-third of its volume and filtered to afford the N-tert-butoxycarbonyl protected intermediate (660 mg).

Trifluoroacetic acid (12.8 mL) was added to a suspension of the protected intermediate (656 mg) in dichloromethane (12.8 mL) and the resulting solution was stirred for 1 hour. Removal of volatile materials under reduced pressure and trituration with diethyl ether gave the crystallized product (1.68 g) as its trifluoroacetate salt 514.MH+206; 1H NMR (DMSOd6) δ 9.2 (br.s, 1H ), 8.75 (br.s, 1H), 8.5 (m, 1H), 7.32 (m, 1H), 3.75 (m, 4H), 3.40 (m, 4H).