One-pot homogeneous process for the large scale manufacture of 2-substituted benzimidazoles
2-substituted benzimidazoles and methods of preparing the same are disclosed. The compositions may include a compound or salt thereof, a strong acid, and a carboxylic acid. The compositions may exclude a polar aprotic solvent. The compositions may be used to inhibit corrosion of a metal surface in contact with an aqueous system, and provide enhanced protection against corrosion of metals in the aqueous system.
1 . A composition, comprising: a strong acid, a carboxylic acid, and a compound or salt thereof of formula (I):
wherein
each X is independently hydrogen, halogen, or a C 1-5 alkyl group, and m is 1, 2, 3, or 4;
R 1 is hydrogen, a C 1 -C 12 alkyl group, or a C 4 -C 6 aryl group;
R 2 is absent, hydrogen, a C 1 -C 12 alkyl group, or a C 4 -C 6 aryl group;
R 3 is a bond or CHR 4 ;
R 4 is hydrogen, halogen, NR 5 R 6 , or OR 5 ;
wherein R 5 and R 6 are each independently hydrogen, a C 1 -C 12 alkyl group, or a C 4 -C 6 aryl group; and
each Z is independently selected from CH and N,
wherein:
the carboxylic acid is acetic acid, and
the composition comprises greater than 10 wt. % to 70 wt. % of the carboxylic acid, and further wherein the composition excludes a polar aprotic solvent.
2 . The composition of claim 1 , further comprising water.
3 . The composition of claim 1 , wherein
each X is independently hydrogen or halogen;
R 1 is hydrogen;
R 2 is absent; and
R 3 is CHR 4 .
4 . The composition of claim 1 , wherein R 3 is a bond and at least one Z is nitrogen.
5 . The composition of claim 1 , wherein the compound or salt thereof is of formula (II)
wherein
Y is independently hydrogen, halogen, or a C 1-5 alkyl group; and n is 1, 2, 3, 4, or 5.
6 . The composition of claim 1 , wherein the strong acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, sulfamic acid, p-toluenesulfonic acid, hydrobromic acid, and any combination thereof.
7 . The composition of claim 1 , further comprising a high temperature stable phase transfer catalyst.
8 . The composition of claim 1 , wherein a concentration of the compound of formula (I), or a salt thereof, in the composition is about 1 wt. % to about 50 wt. %.
9 . A method of inhibiting corrosion, comprising:
adding the composition of claim 1 to an industrial water system comprising a metallic surface.