Cyanogen bromide formation from the reactions of monobromamine and dibromamine with cyanide ion

Hongxia Lei, Roger A. Minear, Benito J. Mariñas

Research output: Contribution to journalArticlepeer-review

Abstract

Cyanide ion (CN-) was found to react with monobromamine (NH 2Br) and dibromamine (NHBr2) according to the reactions NH2Br + CN- + H2O → NH3 + BrCN + OH- and NHBr2 + CN- + H2O → NH2Br + BrCN + OH- with respective reaction rate constants of 2.63 × 104 M-1 s-1 and 1.31 × 108 M-1 s-1. These values were found to be 105-106 times greater than those for the corresponding reactions between chloramine species and CN-. As a result, bromamines, even if present at relatively low concentrations, would tend to outcompete chloramines in reacting with CN-, and thus, the formation of BrCN would predominate that of CICN through these reaction mechanisms. The NH2Br reaction was found to be general-acid-catalyzed. The third-order catalysis rate constants for H+, H2PO 4-, HPO42-, H3BO 3, and NH4+ correlated linearly with their corresponding acid dissociation constants, consistent with the Brønsted-Pedersen relationship. The NHBr2 reaction did not undergo catalysis. A model was developed to predict the concentrations of bromamines over time on the basis of the above two reactions with CN- and bromamine formation/decomposition reactions previously reported.

Original languageEnglish (US)
Pages (from-to)2559-2564
Number of pages6
JournalEnvironmental Science and Technology
Volume40
Issue number8
DOIs
StatePublished - May 15 2006

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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