Carbonodithioic acid, O-(3-methylbutyl) ester

Endpoint summary

Additional information

Abiotic degradation

Solid sodium isobutyl xanthateis hygroscopic, absorbing moisture decomposes, releasing very toxic and extremely flammable carbon disulfide. Decomposition rate increases with increase in temperature and decrease pH.

Decomposition of xanthates depends on temperature and NaOH concentration:

-dx/dt = k₁x + k₂x [NaOH]²

At 65⁰C for: sodium ethyl xanthate (CAS# 140-90-9): k₁= 9.7 10^-4min^-1and k₂= 3.3 10^-4

               sodium isopropyl xanthate (CAS# 140-93-2): k₁= 2.0 10^-4min^-1and k₂= 6.1 10^-5

               sodium n-butyl xanthate (CAS# 141-33-3): k₁= 6.4 10^-4min^-1and k₂= 2.4 10^-5

At 75⁰C for: sodium ethyl xanthate (CAS# 140-90-9): k₁= 2.1 10^-3min^-1and k₂= 6.3 10^-4

             sodium isopropyl xanthate (CAS# 140-93-2): k₁= 4.2 10^-4min^-1and k₂= 1.2 10^-4

             sodium n-butyl xanthate (CAS# 141-33-3): k₁= 1.4 10^-3min^-1and k₂= 4.6 10^-4

It was found that the minimum of xanthates decomposition rate is at pH range from 7 to 9.

(Wronski M., Kinetics of xanthate decomposition in sodium hydroxide solution, Roczniki Chemii, 33, pp1071-1080, 1959)

Investigation of potassium ethyl xanthate(CAS# 140-89-6) water solution at pH 6-10 shoved coexistence of xanthate ions, EtX^-, dixanthogen, (EtX)₂and carbon disulfide(CAS# 75-15-0). (Pomianowski A. , Leja J., (1963)

Simultaneous reactions leading to decomposition of xanthate/or dixanthate species to alcohol and carbon disulfide were detected.

Decomposition of sodium ethyl xanthate as 40% solution at 20⁰C would give rise to an increase in CS₂concentration of approximately 0.1% per day.

(Full Public Report Sodium Ethyl Xanthate Priority Existing Chemical No. 5 May 1995Australian Government Publishing Service Canberra)

Reactivity:Xantates react with oxidizing agents, acids and alkaline solutions. With strog acids the substance decomposes quantitatively producing carbon disulfide and an alcohol. In strong alkali solutions, at pH >13, react forming carbon disulfide, hydrogen, an alcohol, trithiocarbonate and sodium carbonate. Salts of copper, iron, lead or zinc accelerate decomposition of xanthates.

Reaction with strong oxidizing agents as peroxides, nitrates and perchlorates causing risk of fire and explosion.

Solid xanthates decompose exposed to moisture in air, releasing carbon disulfide.

Hydrolysis is a significant factor in determination the environmental fate of xanthates.

In neutral or mildly alkaline water solution, sodium ethyl xanthate decomposes to ethyl alcohol, carbon disulfide, sodium carbonate and sodium trihiocarbonate. (Full Public Report Sodium Ethyl Xanthate Priority Existing Chemical No. 5 May 1995Australian Government Publishing Service Canberra)

Water solutions are also relatively stable at temperature <18⁰C and the pH within the range 10 - 11. (NICNAS. Sodium Ethyl Xanthate. Priority Existing Chemical, Secondary Assessment, Report No. 5S. February 2000)

Biotic degradation                               

After 28 days biodegradation of sodium isopentyl xanthate: D21days = 83.1+/_1.0%

The above results indicate that sodium isopentyl xanthate (CAS#2540-36-5) is readily biodegradable

- pass level, according to OECD 301:

- pass value in the 10 day window (form 0 day to 10 day) is 70% removal of DOC,

Direct or indirect exposure of sediment is unlikely.

 

After 28 days biodegradation of sodium isobutyl xanthate: D28days = 95.4+/_1.1%

The above results indicate that sodium isobutyl xanthate (CAS#25306-75-6) is readily biodegradable

- pass level, according to OECD 301:

- pass value in the 10 day window (form 1 day to 11 day) is 70% removal of DOC,

Direct or indirect exposure of sediment is unlikely.