Hydroxybenzotriazole

Hydroxybenzotriazole

Hydroxybenzotriazole
Space-filling model of the hydroxybenzotriazole molecule
Names
IUPAC name Benzotriazol-1-ol
Other names N-Hydroxybenzotriazole HOBt
Identifiers
CAS Number	2592-95-2 Y 123333-53-9 (hydrate) N
ChemSpider	68282 Y
Jmol 3D model	Interactive image
InChI InChI=1S/C6H5N3O/c10-9-6-4-2-1-3-5(6)7-8-9/h1-4,10H Y Key: ASOKPJOREAFHNY-UHFFFAOYSA-N N InChI=1/C6H5N3O/c10-9-6-4-2-1-3-5(6)7-8-9/h1-4,10H Key: ASOKPJOREAFHNY-UHFFFAOYAP
SMILES n1nn(O)c2ccccc12
Properties
Chemical formula	C6H5N3O
Molar mass	153.134 g mol−1 (hydrate)
Melting point	156 to 159 °C (313 to 318 °F; 429 to 432 K) (decomposes)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Hydroxybenzotriazole (abbreviated HOBt) is an organic compound that is a derivative of benzotriazole. It is a white crystalline powder, which as a commercial product contains some water (~11.7% wt as the HOBt monohydrate crystal). Anhydrous HOBt is explosive.

It is mainly used to suppress the racemization of single-enantiomer chiral molecules and to improve the efficiency of peptide synthesis.

Use in peptide synthesis

Example of a coupling reaction with HOBt

Automated peptide synthesis involves the condensation of the amino group of protected amino acids with the activated ester. HOBt is used to produce such activated esters. These esters are insoluble (like the N-hydroxysuccinimide esters) and react with amines at ambient temperature to give amides.

HOBt is also used for the synthesis of amides from carboxylic acids aside from amino acids. These substrates may not be convertible to the acyl chlorides. For instance amide derivatives of ionophoric antibiotics have been prepared in this way.

Together with laccase, HOBt is also used for bleaching pulps. The method is still in the experimental stage and has not yet been commercialized.

Safety

Due to reclassification as UN0508, a class 1.3C explosive, hydroxybenzotriazole and its monohydrate crystal are no longer allowed to be transported by sea or air as per 49CFR (USDOT hazardous materials regulations). However, UNECE draft proposal ECE/TRANS/WP.15/AC.1/HAR/2009/1 has been circulated to UN delegates and, if implemented, would amend current regulations thus allowing for the monohydrate crystal to be shipped under the less-stringent code of UN3474 as a class 4.1 desensitized explosive.