Tetramethylthiuram Monosulfide and Tetramethylthiuram Disulfide: Heats of Formation and the S—S Thermochemical Bond Energy

1962 ◽  
Vol 35 (3) ◽  
pp. 661-664
Author(s):  
W. D. Good ◽  
J. L. Lacina ◽  
J. P. McCullough
Keyword(s):  
Bond Energy ◽  
Combustion Calorimetry ◽  
Heats Of Formation ◽  
Normal Alkane ◽  
Tetramethylthiuram Disulfide ◽  
Heats Of Combustion

Abstract The heats of combustion and formation were determined for tetramethylthiuram monosulfide [bis-(dimethylthiocarbamoyl) sulfide] and tetramethylthiuram disulfide [bis-(dimethylthiocarbamoyl) disulfide]. The S—S thermochemical bond energy in tetramethylthiuram disulfide was shown to be about the same as in normal alkane disulfides and in S8. Rotating-bomb combustion calorimetry was found satisfactory for compounds that contain both sulfur and nitrogen.

Massenspektrometrische Bestimmung von Bindungsenergien in siliciumorganischen Verbindungen / Mass-spectrometric Determination of Bond Dissoziation Energies in Organosilicon Compounds

1975 ◽  
Vol 30 (3) ◽  
pp. 347-355 ◽  
Author(s):  
P. Potzinger ◽  
A. Ritter ◽  
J. Krause
Keyword(s):  
Bond Energy ◽  
Mass Spectrometric ◽  
Heats Of Formation ◽  
Organosilicon Compounds ◽  
Silicon Compounds ◽  
Mass Spectrometric Determination ◽  
Heats Of Combustion

The appearance potentials for a large number of organosilicon ions have been measured. Combination of these values with thermochemical heats of combustion allow the determination of bond energy terms which may be used to calculate heats of formation for all silicon compounds containing hydrogen, alkyl and chlorine ligands. The bond dissoziation energies D(Si - H)= 89 ± 4, D(Si - C) = 85 ± 4 and D (Si - Si) =75 ± 8 kcal/Mol were found to be independent of the number of methylgroups attached to silicon. In addition the Si - Cl bond energy was found to be 116 and 104 kcal/Mol in (CH3)3SiCl and Cl3SiCl respectively.

Mechanism of the Action of Accelerators of Vulcanization. Vulcanization of Rubber by a Sulfur Radioisotope

1954 ◽  
Vol 27 (4) ◽  
pp. 974-976 ◽  
Author(s):  
G. A. Blokh
Keyword(s):  
Bond Energy ◽  
Disulfide Bonds ◽  
Sodium Sulfite ◽  
Butadiene Rubber ◽  
Exchange Reactions ◽  
Cent Solution ◽  
Tetramethylthiuram Disulfide ◽  
Cold Acetone ◽  
Rubber Accelerators

Abstract The problem of the mechanism of the action of accelerators and vulcanizing agents during the vulcanization of rubber has been studied in earlier works. It was shown that, during the vulcanization of natural and sodium-butadiene rubber, accelerators of the type of mercaptobenzothiazole and tetramethylthiuram disulfide enter into exchange reactions with the vulcanizing agent, sulfur. However, the role of the chemically combined sulfur, that is, the so-called bridge sulfur, in the exchange reactions with the accelerators remained unexplained. As Dogadkin and Tarasova show, in the case of sulfur vulcanizates, the following kinds of bonds between the rubber chains can occur : (1) —C—C—, formed as a result of polymerization or condensation processes (bond energy 62.7 kcal. per mole); (2) —C—S—C—, monosulfide bonds, formed during thiuram vulcanization (bond energy 54.5 kcal. per mole) ; (3) —C—S—S—C—, disulfide bonds; (4) —C—Sn—C—, polysulfides, formed during vulcanization with elemental sulfur in the absence of accelerators containing sulfur (bond energy 27.5 kcal. per mole). These authors established the presence of polysulfide bonds by extracting sulfur from vulcanizates, already extracted with cold acetone, by heating the extracted vulcanizate in a 10 per cent solution of sodium sulfite. Ten to twenty per cent of the total amount of combined sulfur was thus extracted as polysulfide, whereas rubber vulcanized with thiuram contained no sulfur at all which could be extracted by sodium sulfite. In order to study the exchange reactions between accelerators containing sulfur and chemically combined or bridge sulfur, the present investigation was made.

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