Kinetics, thermodynamics, and mechanism of the formation of benzaldehyde-S(IV) adducts

Journal Article · Thu May 22 00:00:00 EDT 1986 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100402a043· OSTI ID:5497140

Olson, T M; Boyce, S D; Hoffmann, M R

The kinetics and mechanism of the formation of ..cap alpha..-hydroxyphenylmethanesulfonate (HPMS) by the addition of bisulfite to benzaldehyde were studied at low pH. A three-term rate law was observed as d(HPMS)/dt - (k/sub 1/..cap alpha../sub 2/ + (k/sub 2/ + k/sub 3/K/sub H-/(H/sup +/))..cap alpha../sub 1/)(S(IV))/sub t/(C/sub 6/H/sub 5/CHO) where ..cap alpha../sub 1/ = (HSO/sub 2//sup -/)/(S(IV)), ..cap alpha../sub 3/ = (SO/sub 2//sup 2 -/)/(S(IV)), and K/sub H/ is the proton association constant of benzaldehyde. The rate-limiting steps of each term appeared to be the nucleophilic attack of SO/sub 3//sup 2 -/ on the carbonyl carbon of benzaldehyde, the attack of HSO/sub 3//sup -/ on the carbonyl carbon, and the attack by HSO/sub 3//sup -/ on the protonated carbon of the carbocation, C/sub 6/H/sub 5/C/sup +/H(OH), respectively. Over the pH range of most natural systems, only the k/sub 1/ and k/sub 2/ steps contribute to adduct formation while the k/sub 3/ term becomes important for pH < 1. At 25/sup 0/C and ..mu.. = 1.0 M, the intrinsic rate constants were determined to be k/sub 1/ = (2.15 +- 0.09) x 10/sup 4/ M/sup -1/ s/sup -1/, k/sub 2/ = (0.71 +- 0.03) M/sup -1/ s/sup -1/, k/sub 3/ approx. 2.5 x 10/sup 7/ M/sup -1/ s/sup -1/. Para-substitution on the benzaldehyde ring resulted in a slight increase in reactivity for p-NO/sub 2/- and p-Cl-, and a decrease for p-OH-, p-OCH/sub 3/-, and p-CH/sub 3/-C/sub 6/H/sub 5/CHO. The equilibrium association constant, K = (C/sub 6/H/sub 5/CH(OH)SO/sub 3//sup -/)/(HSO/sub 3//sup -/)(C/sub 6/H/sub 5/CHO), at 25/sup 0/C was determined to be 4.8 (+-0.8) x 10/sup 3/ at ..mu.. = 0.1 M and 0.98 (+- 0.11) x 10/sup 3/ M/sup -1/ at ..mu.. = 1.0 M. ..delta..H/sup 0/ and ..delta..S/sup 0/ was determined to be -64.6 kJ mol/sup -1/ and -146 J mol/sup -1/ deg/sup -1/, respectively.

• Research Organization: California Institute of Technology, Pasadena
• OSTI ID: 5497140
• Journal Information: J. Phys. Chem.; (United States), Vol. 90:11
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
ADDUCTS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
THERMODYNAMICS
BENZALDEHYDE
SULFUR
EXPERIMENTAL DATA
PREDICTION EQUATIONS
STRUCTURAL CHEMICAL ANALYSIS
ALDEHYDES
DATA
ELEMENTS
EQUATIONS
INFORMATION
KINETICS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
REACTION KINETICS
SYNTHESIS
400301* - Organic Chemistry- Chemical &amp; Physicochemical Properties- (-1987)
500200 - Environment
Atmospheric- Chemicals Monitoring &amp; Transport- (-1989)