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What is Butyl isocyanate?

Feb 19，2020

Butyl isocyanate (N-BUTYL ISOCYANATE; BUTYL ISOCYANATE, STAB.; N-BUTYL ISOCYANATE 99%; Butylisocyanat; HYLENE PARA-PHENYLENEDIISOCYANATE (PPDI); n-butyl isocynate; C5H9NO) is the important raw material or intermediate that has widely applied in the synthesis of pharmaceutical, pesticide and dyestuff products, such as benzimidazole fungicides, sulfonylurea herbicides, and benomyl [1].

Butyl isocyanate is the precursor for the synthesis of benzimidazole fungicides via reacting with methyl 2-benzimidazolecarbamate. a highly reactive decomposition product in various organic solvents or aqueous preparations of both the dry flowable and the wettable powder of benomyl, or methyl l-(butylcarbamoyl)-2-benzimi- dazolecarbamate, which is possible role for phytotoxic symptom in of benomyl [2]. The toxicity of benomyl to the earthworm were contributed to the anti-cholinesterase activity that the cholinesterase inhibitory power of benomyl is from the formation of small quantities of butyl isocyanate. In addition, the mode of action of the benzimidazole analogues for both fungicidal activities might similar to that for earthworm toxicity [3].

Butyl isocyanate is typical catalyst for the synthesis of the sulfonylurea herbicides, such as chlorsulfuron, sulfometuron, metsulfuron-methyl, and chlorimuron-ethyl, by treating the different groups substituted sulfonamide with phosgene in the presence of butyl isocyanate [4]. Moreover, butyl isocyanate is also an intermedia for the synthesis of sulfonylurea. The sulfonylureas could be prepared by the reaction between the sulfonamide and butyl isocyanate in aqueous acetone containing one equivalent of base. The other groups substituted sulfonylurea also could be prepared by reaction of the isocyanate with the groups substituted sulfonamide [5]. A number of novel sulfonylurea derivatives with sugar lowering activity, such as glibenclamide, tolbutamide, chlorpropamide and other hypoglycemic sulfonylurea agents also could be synthesized by using butyl isocyanate as synthetic intermediate.

Fig.1 The synthesis of sulfonylurea by the reaction of the sulfonamide and butyl isocyanate.

Butyl isocyanate has been found that can work as active-site-specific reagent, substrate analog for yeast alcohol dehydrogenase, which contain chemically reactive groups suitable for the specific covalent bond with a sulfhydryl group in three of the enzyme’s four active site [7]. Butyl isocyanate also provides the active-site recognition component and the isocyanate the chemically reactive group which can form covalent derivatives of several functional groups in proteins. For example, papain was inactivated by the reaction of the active-site SH group and stoichiometric amounts of butyl isocyanate at low pH.

Butyl isocyanate has also been worked as precursors for the industries polymers and other products. In conclusion, butyl isocyanate is the important intermediate that can applied in the synthesis of various pharmaceutical, pesticide and industry products.

References

[1] https://www.chemicalbook.com/ProductChemicalPropertiesCB8153607.htm

[2] Tang, C. S., Yanagihara, K., & Zhang, Y. (1992). 1-butyl isocyanate from aqueous Benlate® formulations. Archives of environmental contamination and toxicology, 23(2), 270-272.

[3] Stringer, A., & Wright, M. A. (1976). The toxicity of benomyl and some related 2‐substituted benzimidazoles to the earthworm Lumbricus terrestris. Pesticide Science, 7(5), 459-464.

[4] Levitt, G. (1983). Sulfonylureas: new high potency herbicides. In Pesticide Chemistry: Human Welfare and Environment (pp. 243-250). Pergamon.

[5] Loev, B., Snader, K. M., & Walz, D. T. (1963). The synthesis of some new sulfonylureas. Journal of medicinal chemistry, 6(5), 506-508.