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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: AndersHoveland on May 11, 2012, 01:43:16 AM

Title: Predicting Hydrolysis
Post by: AndersHoveland on May 11, 2012, 01:43:16 AM

Predicting whether a compound will hydrolyse (react) with water can be complicated for those with less experience in chemistry. There are several factors which determine this, including atomic radius size, electronegetivity, double bonds, steric hindrance, and even physical solubility. Without knowing these factors, the reactivity of the following selected compounds could seem inexplicable.
 

Compounds that hydrolyse in water:
 
COCl2 (phosgene)
 SF4
 SCl2
 CSO (carbonyl sulfide)
 CH3Br (bromomethane, insecticide)
CH3I
 

Compounds that do not hydrolyse in water:
 
CCl4 (carbon tetrachloride*, used in some fire extinguishers)
 SF6 (sulfur hexafluoride, non-toxic)
 

Compounds that can reversibly hydrolyse with water:
 
CO2
 SO2
 NCl3 (dangerously unstable explosive)
 

Compounds that only very slowly hydrolyse with water:
 
CS2 (half-life 1.1 years at pH 9)
 CHCl3 (chloroform, half-life of 15 months)
 CH3NO3 (methyl nitrate, explosive ester)
 SO2F2 (sulfuryl fluoride, used as termite fumigant, solubility in water about 1g/L, hydrolysis half-life 3 days at pH 7, but hydrolyses much faster under alkaline conditions, half-life 10 minutes at pH 8.3)
 * actually CCl4 does does hydrolyse, but the reaction rate is neglibable under ordinary conditions, a half life of 7000 years has been calculated)
 

Hopefully this topic will provoke a discussion.
 

Title: Re: Predicting Hydrolysis
Post by: AWK on May 11, 2012, 03:00:57 AM

Quote

Compounds that can reversibly hydrolyse with water:
 
CO2
 SO2
 NCl3 (dangerously unstable explosive)

NCl₃ decomposes completely in water in 24 hours.