THE THERMAL DECOMPOSITION OF DIMETHYL DISULPHIDE

1954 ◽  
Vol 32 (8) ◽  
pp. 768-779 ◽  
Author(s):  
John A. R. Coope ◽  
W. A. Bryce
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Sulphide ◽  
Carbon Disulphide ◽  
Main Reaction ◽  
Methyl Mercaptan ◽  
Primary Reaction ◽  
Gaseous State ◽  
Dimethyl Disulphide ◽  
Volatile Products ◽  
Free Sulphur

The thermal decomposition of dimethyl disulphide has been studied in the gaseous state by a static method. The primary reaction, which follows a reproducible induction period, produces one mole of methyl mercaptan per mole of disulphide, together with a product of low volatility believed to be a thioformaldehyde polymer:[Formula: see text]There is also a competing reaction producing a large quantity of hydrogen sulphide. The remaining volatile products, hydrocarbons of two or more carbon atoms (believed to be chiefly ethylene), free sulphur, polysulphides, and carbon disulphide are formed either by the latter reaction or by the extensive decomposition of products. The decomposition is catalyzed by hydrogen sulphide, and more strongly by the complete reaction mixture. A mechanism is proposed for the main reaction.

PYROLYSIS OF ETHYL MERCAPTAN

1955 ◽  
Vol 33 (8) ◽  
pp. 1281-1285 ◽  
Author(s):  
Jean L. Boivin ◽  
Roderick MacDonald
Keyword(s):  
Hydrogen Sulphide ◽  
Carbon Disulphide ◽  
Optimum Temperature ◽  
Mass Spectral Analysis ◽  
Mass Spectral ◽  
Ethyl Mercaptan ◽  
Catalyst Metal ◽  
Free Sulphur ◽  
Carbonyl Sulphide ◽  
By Products

The decomposition of ethyl mercaptan to ethylene and hydrogen sulphide was studied at various temperatures, with and without a catalyst. Metal sulphides (copper, nickel, and cadmium) proved to be the most efficient catalysts for cracking ethyl mercaptan into unsaturated end products, the optimum temperature being 500–600 °C. When no catalyst was used a 40–50% yield of ethylene and a nearly quantitative conversion to hydrogen sulphide was observed between 600 and 700 °C. Other products identified in the exit gas were carbon disulphide, carbonyl sulphide, methane, hydrogen, ethane, thiophene, diethyl sulphide, and free sulphur. Identification of these products was aided by infrared and mass spectral analysis of the gas. A tentative mechanism for the reaction justifying the presence of the above by-products is outlined.

THE DECOMPOSITION OF DITHIOCARBAMATE FUNGICIDES, WITH SPECIAL REFERENCE TO THE VOLATILE PRODUCTS

1952 ◽  
Vol 30 (2) ◽  
pp. 131-138 ◽  
Author(s):  
L. E. Lopatecki ◽  
W. Newton
Keyword(s):  
Hydrogen Sulphide ◽  
Carbon Disulphide ◽  
Atmospheric Oxygen ◽  
Iron Salts ◽  
Volatile Products ◽  
Metallic Salts ◽  
Dithiocarbamic Acid ◽  
Basic Hydrolysis ◽  
Ethylene Thiourea ◽  
Sodium Diethyl Dithiocarbamate

The gaseous exchange accompanying decomposition of dithiocarbamate fungicides was measured in the Warburg manometer. Sodium diethyl dithiocarbamate decomposed under slightly acid conditions, producing carbon disulphide and a salt of diethylamine. The insoluble zinc and iron salts of dimethyl dithiocarbamic acid also decomposed in a similar fashion, but no carbon disulphide was given off from the more stable copper salt of this compound. The rate of decomposition of these metallic salts fell in the following decreasing order:[Formula: see text]Disodium ethylene bis-dithiocarbamate (nabam) decomposed under slightly acid conditions to produce approximately equal volumes of hydrogen sulphide and carbon disulphide, and presumably left a residue of ethylene thiourea. In distilled water, on the other hand, nabam underwent a slow basic hydrolysis and oxidation, with absorption of approximately two volumes of oxygen, and evolution of one volume of carbon disulphide. Apparently the sulphur fraction which is evolved as hydrogen sulphide from nabam under acid conditions is, under basic conditions, oxidized in solution by atmospheric oxygen to sulphate.

The photochemical and thermal decompositions of hydrogen sulphide

1953 ◽  
Vol 216 (1126) ◽  
pp. 344-361 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Quantum Yield ◽  
Hydrogen Sulphide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Fraction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Photochemical Decomposition ◽  
Bimolecular Mechanism

The photochemical decomposition of hydrogen sulphide has been investigated at pressures between 8 and 550 mm of mercury and at temperatures between 27 and 650° C, using the narrow cadmium line ( λ 2288) and the broad mercury band (about λ 2550). At room temperature the quantum yield increases with pressure from 1.09 at 30 mm to 1.26 at 200 mm. Above 200 mm pressure there was no further increase in the quantum yield. Temperature had little effect on the quantum yield at λ 2550, but there was a marked increase in the rate of hydrogen production between 500 and 650° C with 2288 Å radiation. This may have been caused by the decomposition of excited hydrosulphide radicals. The results are consistent with a mechanism involving hydrogen atoms and hydrosulphide radicals. The mercury-photosensitized reaction is less efficient than the photochemical decomposition, the quantum yield being only about 0.45. The efficiency increased with temperature and approached unity at high temperatures and pressures. This agrees with the suggestion that a large fraction of the quenching collisions lead to the formation of Hg ( 3 P 0 ) atoms. The thermal decomposition is heterogeneous at low temperatures and becomes homogeneous and of the second order at 650° C. The experimental evidence suggests the bimolecular mechanism 2H 2 S → 2H 2 + S 2 . The activation energies are 25 kcal/mole (heterogeneous) and 50 kcal/mole (homogeneous).

Volatile Products Formed in the Thermal Decomposition of a Tobacco Substrate

2013 ◽  
Vol 52 (42) ◽  
pp. 14984-14997 ◽  
Author(s):  
Federica Barontini ◽  
Alessandro Tugnoli ◽  
Valerio Cozzani ◽  
John Tetteh ◽  
Marine Jarriault ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Volatile Products

Effect of sulphur compounds on the heptane pyrolysis kinetics

1985 ◽  
Vol 50 (12) ◽  
pp. 2893-2902 ◽  
Author(s):  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Thermal Decomposition ◽  
Stainless Steel ◽  
Carbon Disulphide ◽  
Reaction Times ◽  
Pyrolysis Kinetics ◽  
Sulphur Compounds ◽  
Dithiophosphoric Acid ◽  
Tube Reactor ◽  
Flow Through ◽  
Steel Flow

The effect of 1-didecyl sulphide, diethyl disulphide, p,p'-dichlorodiphenyl disulphide, 1-butanethiol, 0,0'-di-1-butyl dithiophosphate zinc, 0,0'-diethyl dithiophosphoric acid and carbon disulphide, respectively, on the kinetics and selectivity of the thermal decomposition of heptane at 700 °C and 100 kPa was studied in a stainless steel flow-through tube reactor. The sulphur substance content was 0.1-1.0 wt.%. 1-Didecyl sulphide, p,p'-dichlorodiphenyl disulphide, 1-butylthiol, 0,0'-di-1-butyl dithiophosphate zinc and carbon disulphide favour the decomposition of heptane by 5-17%. A decrease in the heptane decomposition rate was observed in the presence of diethyl disulphide (2.8%) and 0,0'-diethyl dithiophosphoric acid (13.9%). The selectivity of decomposition to ethylene is increased by diethyl disulphide, p,p'-dichlorodiphenyl disulphide, carbon disulphide and 1-didecyl sulphide and, in the range of short reaction times, also by 0,0'-diethyl dithiophosphoric acid, 0,0'-di-1-butyl dithiophosphate zinc and 1-butanethiol.

Electron Optical Study of the Thermal Decomposition of Kaolinite

Clay Minerals ◽  
1970 ◽  
Vol 8 (3) ◽  
pp. 279-290 ◽  
Author(s):  
J. D. C. McConnell ◽  
S. G. Fleet
Keyword(s):  
Thermal Decomposition ◽  
Reaction Mechanisms ◽  
Spinel Phase ◽  
Oxide Phase ◽  
Secondary Development ◽  
Main Reaction ◽  
Optical Study ◽  
Limited Extent ◽  
Microporous Structure ◽  
Temperature Range

AbstractThe electron microscope has been used to study the mechanisms of thermal decomposition of kaolinite in the temperature range 800-1350°C. Three main reaction mechanisms appear to be important in this temperature range. At 850°C metakaolinite breaks down to produce an amorphous defect oxide phase which is homogeneous and finely porous. When heated at 900°C the reaction product is a defect spinel with strongly preferred orientation and microporous structure. This defect spinel phase is observed in the temperature range 900-1150°C and shows little change in microstructure throughout this temperature range where the secondary development of muUite also occurs to a limited extent. Above 1150°C mullite develops in quantity and appears to represent the bulk of the reaction product at 1200°C.

Changes in Concentration of Volatile Sulphur Compounds of Mouth Air during the Menstrual Cycle

1978 ◽  
Vol 6 (3) ◽  
pp. 245-254 ◽  
Author(s):  
Joseph Tonzetich ◽  
George Preti ◽  
George R Huggins
Keyword(s):  
Menstrual Cycle ◽  
Hydrogen Sulphide ◽  
Maximum Level ◽  
Methyl Mercaptan ◽  
Physiological Changes ◽  
Sulphur Compounds ◽  
Volatile Sulphur Compounds ◽  
Vaginal Secretions ◽  
Cyclic Variations ◽  
Cyclic Changes

Five female subjects were studied to determine the applicability of volatile sulphur analysis of mouth air to monitor chemical, cytological and physiological changes observed during the menstrual cycle. Volatile sulphur results were compiled over twelve ovulatory cycles derived from two or three consecutive cycles from each subject. The results of mouth air evaluations were compared with concurrently determined levels of hormones in blood serum and organic metabolites in vaginal secretions. Distinct cyclic variations were observed in concentrations of all three volatile sulphur components (hydrogen sulphide, methyl mercaptan and dimethyl sulphide) of mouth air. There was a definite overall trend for the compounds to increase two- to four-fold immediately around mid-cycle and menstruation as well as during mid-proliferative and mid-luteal phases of each menstrual cycle. In those cycles in which hormonal profiles were obtained, the increase in volatile sulphur content closely coincided with the mid-cycle surge in luteinizing hormone, while the peak during the mid-luteal phase corresponded to a period of maximum level of progesterone and elevated oestrogens. The concentrations of lactic acid and urea in vaginal secretions also underwent cyclic changes analogous to those described for volatile sulphur components of mouth air. The occurrence of malodourous concentrations of hydrogen sulphide and methyl mercaptan immediately around menses in most of the cycles studied satisfactorily accounts for the reported incidence of breath malodour observed during this time.

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