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A method for the determination of dixanthogens
Talanta.1961.Vol. 8, PP. 746to 758. Pergzunon PressLtd. PrintedittNorthernIreland
SHORT COMMUNICATIONS
A method for the determination of dixanthogens (Received 6 March 1961.
Accepted 19 June 1961)
A METHOD for the determination of dixanthogens has been developed based on the action of chloramine-T on dixanthogen. The action of chloramine-T on xanthates has been studied by Rao and Mm-thy’ who have utilised the reaction as a means of determining carbon disulphide after converting it into ethyl xanthate. It was suggested that the reaction can be extended to dixanthogens and so experiments were conducted to study the action of chloramine-T on diethyl, dibutyl and diamyl dixanthogens, with a view to standardising their methods of determination. Reagents Chlorumine-T: O.lN solution prepared by dissolving a recrystallised sample of chloramine-T (145 g per litre) and standardising iodimetrically in an acid medium as described earlier.*‘” Diethyl dixanthogen: Pure potassium ethyl xanthate was oxidised by iodine to obtain an insoluble oily diethyl dixanthogen. The oil was extracted with petroleum ether and the solvent evaporated in vacuum. The resulting diethyl dixanthogen had a melting point’ of 28”. Analysis for sulphur (Carius) 53.12%; calculated 52.93 %. Dibutyl and diamyl dixanthogens were prepared under similar experimental conditions using the corresponding freshly prepared xanthates. Dixanthogens are insoluble in water, but soluble in alcohol. Alcohol solutions of dixanthogens of known concentration were therefore used for purposes of oxidation. Alcohol is not oxidised by chloramine-T under the experimental conditions employed. Procedure A known amount of dixanthogen was mixed with an excess of aciditled chloramine-T (10 ml of 0.W with 5 ml of 2N HCl) in an Erlenmeyer flask and set aside for 1 hr. Then 10 ml of 10% TABLE I.
Dixanthogen Diethyl Dibutyl Diamyl
OXIDATION OF DIXANTH~GENS BY CHLORAMINE-T
Dixanthogen taken, moles x 106
Chloramine-T consumed, equivalents x lop
260 1.92 1.86 2.02 1.78 2.06
6.17 5GO 3.41 3.80 3.19 3.66
Chloramine-T per mole of dixanthogen, equivalents 26.03 25.93 18.71 18.84 17.86 17.74
potassium iodide were added and the liberated iodine was titrated against standard thiosulphate solution. From the amount of chloramine-T consumed the number of equivalents of the oxidant required per mole of dixanthogen was calculated. The experimental results were found to be reproducible and are presented in Table I. The above table shows that 1 mole of diethyl dixanthogen consumes 26 equivalents of 746
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chloramine-T. This can be explained by the following mechanism, which is similar to that proposed for the oxidation of xanthate by chloramine-T in acid medium? S
S
II
II
C,H,O-C-S-S-C-OC,H,
f 130 + 7Ha0 + 2CaH,0H
+ 4HzS0, + ZHCOOH
This quantitative reaction can be employed as an elegant method for the determination of diethyl dixanthogen. Reactions between dibutyl and diamyl dixanthogens and chloramine-T were found to be more complicated, consuming only 18-19 equivalents of chloramine-T instead of 26 equivalents. The heavier alkyl radical attached to the carbon atom is perhaps responsible for the incomplete oxidation of carbon disulphide (xanthate or dixanthogen) to formic acid and sulphuric acid. However, with calibration even these can be estimated conveniently. AcknowZedgemerr&-The author wishes to express his grateful thanks to Prof. M. R. A. Rao for his keen interest in the work. S. RAMACH.~NDRARA~ Dept. of Inorganic and Physical Chemistry Indian Institute of Science Lbgalore, 12, S. India Summary-_One mole of diethyl dixanthogen reacts with 26 moles of chloramine-T, and this reaction can be used for the determination of the dixanthogen. Higher alkyl dixanthogens react in a more complicated fashion, but may still be estimated using an empirical correction. Znsamn~enfassnng-Ein Mole Diathyldixangthogenat reagiert mit 26 Molen Chloramin-T, was zur Bestimmung von Dixanthogenat herangezogen werden kann. Hiihere Alkylxanthogenate reagieren in komplizierter Weise, konnen jedoch gleichfalls be&runt werden, wenn eine empirische Korrektur angebracht wird. R&nm&XJne mole de diethyldixanthogene reagit sur 26 moles de chloramine T; cette reaction peut 2tre utili& pour le dosage du dixanthogene. Les alcoyl dixanthogenes superieurs reagissent de man&e plus compliqu&e, mais ils peuvent encore &tre doses en faisant une correction empirique. REFERENCES 1 V. a A. BE. 4 R.
R. S. Rao and R. V. Mm-thy Bishop and V. Nasini and A.
A. R. V. Murthy, Talanta, 1960,4,206. and B. S. Rao, Proc. Ind. Acad. Sci., 1952,35A, 7. J. Jennings, Talanta, 1958,1, 197. Scala, Gazz. Chim. ItaZ., 1887, 17, 75.
A self-sampling indicator tube for carbon dioxide (Received 8 May 1961. Accepted 20 May 1961) FOLLOWING the development of an indicator tube for the determination of oxygen in air,‘ea the production of a similar type of test for carbon dioxide covering the range 10-90% has been investigated. This work was undertaken mainly to provide a simple and rapid means of obtaining the correction for the oxygen tube when it is used in the presence of appreciable amounts of carbon dioxide,‘,* produced by combustion or respiration. Such a test would also be useful in industrial . . apphcatrons where the oxygen content of an atmosphere has to be reduced to minimise fire or explosion risks (e.g. in the grinding of inflammable powders such as sulphur) by dilution with carbon dioxide or flue gases which contain a high proportion of carbon dioxide. Both the oxygen and carbon dioxide tests employ reagents contained in evacuated glass tubes. To use the tubes, the sealed end is broken and the entering gas changes the wlour of the reagent over a distance which depends on the concentration of reacting gas (oxygen or carbon dioxide).
SHORT COMMUNICATIONS
A method for the determination of dixanthogens (Received 6 March 1961.
Accepted 19 June 1961)
A METHOD for the determination of dixanthogens has been developed based on the action of chloramine-T on dixanthogen. The action of chloramine-T on xanthates has been studied by Rao and Mm-thy’ who have utilised the reaction as a means of determining carbon disulphide after converting it into ethyl xanthate. It was suggested that the reaction can be extended to dixanthogens and so experiments were conducted to study the action of chloramine-T on diethyl, dibutyl and diamyl dixanthogens, with a view to standardising their methods of determination. Reagents Chlorumine-T: O.lN solution prepared by dissolving a recrystallised sample of chloramine-T (145 g per litre) and standardising iodimetrically in an acid medium as described earlier.*‘” Diethyl dixanthogen: Pure potassium ethyl xanthate was oxidised by iodine to obtain an insoluble oily diethyl dixanthogen. The oil was extracted with petroleum ether and the solvent evaporated in vacuum. The resulting diethyl dixanthogen had a melting point’ of 28”. Analysis for sulphur (Carius) 53.12%; calculated 52.93 %. Dibutyl and diamyl dixanthogens were prepared under similar experimental conditions using the corresponding freshly prepared xanthates. Dixanthogens are insoluble in water, but soluble in alcohol. Alcohol solutions of dixanthogens of known concentration were therefore used for purposes of oxidation. Alcohol is not oxidised by chloramine-T under the experimental conditions employed. Procedure A known amount of dixanthogen was mixed with an excess of aciditled chloramine-T (10 ml of 0.W with 5 ml of 2N HCl) in an Erlenmeyer flask and set aside for 1 hr. Then 10 ml of 10% TABLE I.
Dixanthogen Diethyl Dibutyl Diamyl
OXIDATION OF DIXANTH~GENS BY CHLORAMINE-T
Dixanthogen taken, moles x 106
Chloramine-T consumed, equivalents x lop
260 1.92 1.86 2.02 1.78 2.06
6.17 5GO 3.41 3.80 3.19 3.66
Chloramine-T per mole of dixanthogen, equivalents 26.03 25.93 18.71 18.84 17.86 17.74
potassium iodide were added and the liberated iodine was titrated against standard thiosulphate solution. From the amount of chloramine-T consumed the number of equivalents of the oxidant required per mole of dixanthogen was calculated. The experimental results were found to be reproducible and are presented in Table I. The above table shows that 1 mole of diethyl dixanthogen consumes 26 equivalents of 746
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chloramine-T. This can be explained by the following mechanism, which is similar to that proposed for the oxidation of xanthate by chloramine-T in acid medium? S
S
II
II
C,H,O-C-S-S-C-OC,H,
f 130 + 7Ha0 + 2CaH,0H
+ 4HzS0, + ZHCOOH
This quantitative reaction can be employed as an elegant method for the determination of diethyl dixanthogen. Reactions between dibutyl and diamyl dixanthogens and chloramine-T were found to be more complicated, consuming only 18-19 equivalents of chloramine-T instead of 26 equivalents. The heavier alkyl radical attached to the carbon atom is perhaps responsible for the incomplete oxidation of carbon disulphide (xanthate or dixanthogen) to formic acid and sulphuric acid. However, with calibration even these can be estimated conveniently. AcknowZedgemerr&-The author wishes to express his grateful thanks to Prof. M. R. A. Rao for his keen interest in the work. S. RAMACH.~NDRARA~ Dept. of Inorganic and Physical Chemistry Indian Institute of Science Lbgalore, 12, S. India Summary-_One mole of diethyl dixanthogen reacts with 26 moles of chloramine-T, and this reaction can be used for the determination of the dixanthogen. Higher alkyl dixanthogens react in a more complicated fashion, but may still be estimated using an empirical correction. Znsamn~enfassnng-Ein Mole Diathyldixangthogenat reagiert mit 26 Molen Chloramin-T, was zur Bestimmung von Dixanthogenat herangezogen werden kann. Hiihere Alkylxanthogenate reagieren in komplizierter Weise, konnen jedoch gleichfalls be&runt werden, wenn eine empirische Korrektur angebracht wird. R&nm&XJne mole de diethyldixanthogene reagit sur 26 moles de chloramine T; cette reaction peut 2tre utili& pour le dosage du dixanthogene. Les alcoyl dixanthogenes superieurs reagissent de man&e plus compliqu&e, mais ils peuvent encore &tre doses en faisant une correction empirique. REFERENCES 1 V. a A. BE. 4 R.
R. S. Rao and R. V. Mm-thy Bishop and V. Nasini and A.
A. R. V. Murthy, Talanta, 1960,4,206. and B. S. Rao, Proc. Ind. Acad. Sci., 1952,35A, 7. J. Jennings, Talanta, 1958,1, 197. Scala, Gazz. Chim. ItaZ., 1887, 17, 75.
A self-sampling indicator tube for carbon dioxide (Received 8 May 1961. Accepted 20 May 1961) FOLLOWING the development of an indicator tube for the determination of oxygen in air,‘ea the production of a similar type of test for carbon dioxide covering the range 10-90% has been investigated. This work was undertaken mainly to provide a simple and rapid means of obtaining the correction for the oxygen tube when it is used in the presence of appreciable amounts of carbon dioxide,‘,* produced by combustion or respiration. Such a test would also be useful in industrial . . apphcatrons where the oxygen content of an atmosphere has to be reduced to minimise fire or explosion risks (e.g. in the grinding of inflammable powders such as sulphur) by dilution with carbon dioxide or flue gases which contain a high proportion of carbon dioxide. Both the oxygen and carbon dioxide tests employ reagents contained in evacuated glass tubes. To use the tubes, the sealed end is broken and the entering gas changes the wlour of the reagent over a distance which depends on the concentration of reacting gas (oxygen or carbon dioxide).