2-Mercaptobenzimidazole

Description

2-Mercaptobenzimidazole is a very useful corrosion inhibitor and cleaner. It can be used to remove the mercury (II) from aqueous solutions and chlor-alkali industry wastewater¹. It can be added to the surface film to inhibit the corrosion of metals like copper^2-3 and mild steel⁴. It can also be used as the carrier for the coated-wire mercury (II)-selective electrodes⁵.
2-Mercaptobenzimidazole is also used as an anti-degradant. It is utilized for protecting rubber from oxidation. It is also employed as an intermediate in the preparation of rabeprazole. Further, it finds application in anti-leprosy drugs in medicine⁶.

Reference

1. Manohar, D. M., K. A. Krishnan, and T. S. Anirudhan. "Removal of mercury (II) from aqueous solutions and chlor-alkali industry wastewater using 2-mercaptobenzimidazole-clay." Water Research 36.6(2002):1609.
2. Chadwick, D., and T. Hashemi. "Electron spectroscopy of corrosion inhibitors: Surface films formed by 2-mercaptobenzothiazole and 2-mercaptobenzimidazole on copper." Surface Science 89.1(1979):649-659.
3. Trachli, B., et al. "Protective effect of electropolymerized 2-mercaptobenzimidazole upon copper corrosion." Progress in Organic Coatings 44.1(2002):17-23.
4. Wang, Lin. "Evaluation of 2-mercaptobenzimidazole as corrosion inhibitor for mild steel in phosphoric acid." Corrosion Science 43.12(2001):2281-2289.
5. Mazloum, M, M. K. Amini, and I. Mohammadpoor-Baltork. "Mercury selective membrane electrodes using 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, and hexathiacyclooctadecane carriers." Sensors & Actuators B Chemical 63.1(2000):80-85.
6. https://www.alfa.com/en/catalog/A18350/

Chemical Properties

yellow or white crystals

Uses

An antidegradant, protecting rubber from oxidation. An intermediate in the synthesis of Rabeprazole (R070500)

Uses

2-Mercaptobenzimidazole is used as an antidegradant. It is utilized for protecting rubber from oxidation. It is also employed as an intermediate in the preparation of rabeprazole. Further, it finds application in anti-leprosy drugs in medicine. In addition to this, it is used as a copper plating brightener.

Synthesis Reference(s)

Organic Syntheses, Coll. Vol. 4, p. 569, 1963
The Journal of Organic Chemistry, 29, p. 3209, 1964 DOI: 10.1021/jo01034a020

General Description

White to yellow crystals or cream colored powder. Slight odor.

Air & Water Reactions

Dust explosion: 0.140 oz/ft3. Insoluble in water. 2-Mercaptobenzimidazole is moisture sensitive. .

Reactivity Profile

An organosulfide and an amine. Organosulfides are incompatible with acids, diazo and azo compounds, halocarbons, isocyanates, aldehydes, alkali metals, nitrides, hydrides, and other strong reducing agents. Reactions with these materials generate heat and in many cases hydrogen gas. Many of these compounds may liberate hydrogen sulfide upon decomposition or reaction with an acid. Amines are chemical bases. They neutralize acids to form salts plus water. These acid-base reactions are exothermic. The amount of heat that is evolved per mole of amine in a neutralization is largely independent of the strength of the amine as a base. Amines may be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen is generated by amines in combination with strong reducing agents, such as hydrides.

Fire Hazard

Flash point data for 2-Mercaptobenzimidazole are not available; however, 2-Mercaptobenzimidazole is probably combustible.

Flammability and Explosibility

Non flammable

Safety Profile

Poison by intraperitoneal and intravenous routes. Moderately toxic by ingestion. Skin and eye irritant. When heated to decomposition it emits toxic fumes of SO, and NO,. See also MERCAPTANS.

Purification Methods

Crystallise it from aqueous EtOH, AcOH or aqueous ammonia. It complexes with many metals. [Brown J Chem Soc 1976 1958, Beilstein 24 II 65, 24 III/IV 287.]