Non-metal redox kinetics: general-acid-assisted reactions of chloramine with sulfite and hydrogen sulfite

Journal Article · Wed Oct 21 00:00:00 EDT 1987 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00268a006· OSTI ID:7148412

Yiin, B S; Walker, D M; Margerum, D W

The rate expression for chloramine oxidation of sulfite is -d(NH/sub 2/Cl)dt = k/sub HA/(HA)(SO/sub 3//sup 2 -/)/sub T/(NH/sub 2/Cl), where HA is a general acid and (SO/sub 3//sup 2 -/)/sub T/ = (SO/sub 3//sup 2 -/) + (SHO/sub 3//sup -/) is the sum of concentrations of the isomeric forms HSO/sub 3//sup -/ and SO/sub 3/H/sup -/). Rate constants (M/sup -2/ s/sup -1/, except as noted, 25.0/sup 0/C, ..mu.. = 0.50) are resolved for the SO/sub 3//sup 2 -/ reactions where HA = H/sub 3/O/sup +/ (8 x 10/sup 10/), H/sub 2/PO/sub 4//sup -/ (1.3 x 10/sup 6/), SHO/sub 3//sup -/ (3.7 x 10/sup 5/), B(OH)/sub 3/ (5.8 x 10/sup 3/), NH/sub 4//sup +/ (1.7 x 10/sup 2/) and H/sub 2/O (7.7 M/sup -1/ s/sup -1/). The k/sub HA/ values increase with the acid strength of HA (Broensted ..cap alpha.. = 0.71). In the proposed transition state, simultaneous H/sup +/ transfer from HA to NH/sub 2/Cl and Cl/sup +/ transfer from NH/sub 2/Cl to SO/sub 3//sup 2 -/ occurs. The ClSO/sub 3//sup -/ thus formed hydrolyzes rapidly to give SO/sub 4//sup 2 -/ and Cl/sup -/. The NH/sub 2/Cl reaction with SHO/sub 3//sup -/ also is assisted by acids, and k/sub HA/ values (M/sup -2/ s/sup -1/) are resolved for H/sub 3/O/sup +/ (3.6 x 10/sup 8/), CH/sub 3/COOH (2 x 10/sup 5/), H/sub 2/PO/sub 4//sup -/ (2 x 10/sup 5/), and SHO/sub 3//sup -/ (1.3 x 10/sup 6/). Since the latter three acids have k/sub HA/ values of the same magnitude, cyclic transition states are proposed in which these acids donate a proton NH/sub 2/Cl and accept a proton from SHO/sub 3//sup -/, as the Cl/sup +/ transfers from nitrogen to sulfur.

• Research Organization: Purdue Univ., West Lafayette, IN (USA)
• OSTI ID: 7148412
• Journal Information: Inorg. Chem.; (United States), Vol. 26:21
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
CHLORAMINES
CHEMICAL REACTIONS
HYDROGEN COMPOUNDS
OXIDATION
SULFITES
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
QUANTITY RATIO
REDOX REACTIONS
AMINES
DATA
INFORMATION
KINETICS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
REACTION KINETICS
SULFUR COMPOUNDS
400201* - Chemical & Physicochemical Properties
520100 - Environment
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