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Environmental fate & pathways

Hydrolysis

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Description of key information

CTC is considered stable against abiotic hydrolysis under environmental conditions.

Key value for chemical safety assessment

Additional information

The rate of hydrolysis in water is second order with respect to CTC, but is extremely slow, with a calculated half-life of 7,000 years at a concentration of 1 ppm according to Mabey and Mill (1978), whereas Jeffers et al (1989) estimated the half-life for hydrolysis at 25 °C and pH 7 to be 40.5 years. Haag & Yao (1992) reported the aqueous hydrolysis rate to be < 2 · 10-6 M-1 s-1, calculated from gas phase measurements. A second order reaction rate constant of 3 · 1010 L  mol-1s-1with hydrated electrons at ambient temperature was measured by Anbar & Neta (1967). This value underlines the considered insignificance of hydrolytical CTC transformation.

 

Therefore, hydrolysis is not a degradation relevant process for carbon tetrachloride under environmental conditions.

 

Decreasing CTC concentrations with depth in the ocean have been observed by Lovelock et al (1973) and it was suggested that hydrolysis may be the cause of it. But this decrease is more likely caused by biodegradation of CTC, occurring more readily,

particularly under anaerobic conditions.