Evaluation of amines as bases for the H2O2-Cl2 singlet-oxygen generation reaction

Abstract

The performance of a sparger-type, singlet-delta-oxygen generator using various amines as alternative bases to NaOH was found to be comparable to the performance of a generator with the Cl2-NaOH-H2O2-H2O reactant system. Based on the percentage of singlet-oxygen evolution from the generator and the known rates of reaction between Cl2 and propylamine, the reaction between Cl2 and HO−2, which is assumed to produce singlet oxygen, is estimated to be ∼108 M−1 s−1.

Production of singlet oxygen by the reaction of non-basic hydrogen peroxide with chlorine gas

“…As OH À is by far a stronger base than HO 2 À (see Table 1), almost all the MtOH would be changed into MtO 2 H so that the components of BHP are virtually H 2 O, H 2 O 2 , HO 2 À and Mt + , with H 2 O 2 mainly existing in the form of HO 2 À ions. 6 The Cl 2 + BHP reaction thus has always been considered to be the reaction of Cl 2 with HO 2 À ions, 6,7 Cl…”

“…The second order rate constant of Reaction (1), k 1 , has been measured to be B10 8 M À1 s À1 . 7 In contrast to BHP, as the base in non-basic hydrogen peroxide (nBHP) is by far a weaker base than HO 2 À (see Please note that safeguards must be taken when dealing with C 5 H 5 N, NH 4 F and H 2 O 2 . C 5 H 5 N vapor is harmful if inhaled; one should prepare nBHP-1 (C 5 H 5 N) in a fume cupboard and minimize its exposure time to the air.…”

“…7 In [HOO À -ClÁ Á ÁCl] a , the O-Cl bond gradually forms as the Cl-Cl bond gradually breaks up, and after undergoing the electron transfer it splits into HOOCl and Cl À . Subsequently, HOOCl ionizes into ClOO À and H + .…”

“…As OH À is by far a stronger base than HO 2 À (see 2 À ions. 6 The Cl 2 + BHP reaction thus has always been considered to be the reaction of Cl 2 with HO 2 À ions, 6,7 Cl 2 þ 2HO 2…”

“…7 In contrast to BHP, as the base in non-basic hydrogen peroxide (nBHP) is by far a weaker base than HO 2 À (see …”