Sulfur Crosslinks in Polybutadiene Vulcanizates

1969 ◽  
Vol 42 (4) ◽  
pp. 1136-1146 ◽  
Author(s):  
Earl C. Gregg
Keyword(s):  
Methyl Iodide ◽  
Sulfur Atom ◽  
Rate Equation ◽  
Methyl Bromide ◽  
Cleavage Rate ◽  
First Time ◽  
Secondary Carbon

Abstract For the first time the crosslink terminus structure of monosulfide crosslinks and the amount of that structure in an elastomer vulcanizate has been determined directly from a sample of the vulcanizate. By measuring the rate of swelling of vulcanizates, immersed in either methyl iodide or methyl bromide, the rate of crosslink cleavage was measured. Comparison of this cleavage rate with the cleavage rate of model monosulfide compounds permits a measure of the terminus structure of the monosulfide crosslinks. The fraction of each monosulfide structure was determined from the cleavage rate equation for the vulcanizate. The monosulfide crosslink terminus structure in a particular polybutadiene vulcanizate was found to be saturated, having secondary carbon atoms on both sides of the sulfur atom, i.e., it was a saturated, tetrafunctional crosslink equal to 38% of the total crosslinks.

The kinetics of the decarboxylation of β-resorcylic acid in catechol

1976 ◽  
Vol 29 (2) ◽  
pp. 443 ◽  
Author(s):  
MA Haleem ◽  
MA Hakeem
Keyword(s):  
Rate Equation ◽  
Kinetic Data ◽  
Reaction Rate ◽  
Complex Mechanism ◽  
First Order ◽  
Absolute Reaction Rate ◽  
First Time ◽  
Kinetics Of ◽  
Absolute Reaction ◽  
Reaction Rate Equation

Kinetic data are reported for the decarboxylation of β-resorcylic acid in resorcinol and catechol for the first time. The reaction is first order. The observation supports the view that the decomposition proceeds through an intermediate complex mechanism. The parameters of the absolute reaction rate equation are calculated.

Palladium-promoted sulfur atom migration on carboranes: facile B(4)−S bond formation from mononuclear Pd-B(4) complexes

2018 ◽  
Vol 90 (4) ◽  
pp. 607-616
Author(s):  
Yin-Ping Wang ◽  
Yue-Jian Lin ◽  
Guo-Xin Jin
Keyword(s):  
Sulfur Atom ◽  
Bond Formation ◽  
Reaction Process ◽  
One Pot ◽  
Leaving Group ◽  
Atom Migration ◽  
First Time

AbstractFor the first time, carborane complexes containing a B(4)–S bond were obtained directly by heating mononuclear Pd-B(4)-bound carborane complexes. A possible mechanism involved in sulfur atom migration is presented in which the leaving group, pyridine, benzyl isocyanide or PPh3, is demonstrated to be the trigger of the reaction process. In this work, efficient routes are developed through one-pot reactions to prepare B(4)-S carborane derivatives.

THE CHEMICAL STABILITY OF THE S-METHYL XANTHATES OF SOME SIMPLE ALCOHOLS

1956 ◽  
Vol 34 (9) ◽  
pp. 1302-1314 ◽  
Author(s):  
D. L. Vincent ◽  
C. B. Purves
Keyword(s):  
Hydrogen Peroxide ◽  
Methyl Ester ◽  
Methyl Iodide ◽  
Chemical Stability ◽  
Periodic Acid ◽  
High Yield ◽  
Methylating Agents ◽  
First Time ◽  
Oxygen Atoms

n-Octadecyl S-methyl xanthate, m.p. 38–39°, and n-hexadecyl S-methyl xanthate, m.p. 28–28.5°, were prepared for the first time, and were used to study the behavior of the S-methyl xanthate group toward reagents commonly used in research on carbohydrates. Although stable to some conditions of acetylation, hydrolysis, and methanolysis, the S-methyl xanthate group was destroyed by all methylating agents tried, with the exception of nitrosomethylurethane. The latter reagent converted a sodium xanthate salt in high yield to the S-methyl ester. Octadecyl and hexadecyl S-methyl xanthates when oxidized with hydrogen peroxide yielded crystalline substances of composition C20H40O4S2 and C18H36O4S2, respectively, whose structures were not determined. These substances each contained three additional oxygen atoms. Various attempts to estimate the S-methyl xanthate group by oxidation with bromine or periodic acid, or by reduction to methyl iodide, were unsuccessful.

Methyl bromide, other brominated methanes, and methyl iodide in polar firn air

2001 ◽  
Vol 106 (D2) ◽  
pp. 1595-1606 ◽  
Author(s):  
W. T. Sturges ◽  
H. P. McIntyre ◽  
S. A. Penkett ◽  
J. Chappellaz ◽  
J.-M. Barnola ◽  
...  
Keyword(s):  
Methyl Iodide ◽  
Methyl Bromide

scholarly journals Strain IMB-1, a Novel Bacterium for the Removal of Methyl Bromide in Fumigated Agricultural Soils

1998 ◽  
Vol 64 (8) ◽  
pp. 2899-2905 ◽  
Author(s):  
Tracy L. Connell Hancock ◽  
Andria M. Costello ◽  
Mary E. Lidstrom ◽  
Ronald S. Oremland
Keyword(s):  
Methyl Iodide ◽  
Methyl Bromide ◽  
Agricultural Soils ◽  
Treatment Strategies ◽  
Methyl Chloride ◽  
Methylotrophic Bacterium ◽  
Rrna Gene ◽  
Low Concentrations ◽  
Novel Bacterium ◽  
Bacterium Strain

ABSTRACT A facultatively methylotrophic bacterium, strain IMB-1, that has been isolated from agricultural soil grows on methyl bromide (MeBr), methyl iodide, methyl chloride, and methylated amines, as well as on glucose, pyruvate, or acetate. Phylogenetic analysis of its 16S rRNA gene sequence indicates that strain IMB-1 classes in the alpha subgroup of the class Proteobacteria and is closely related to members of the genus Rhizobium. The ability of strain IMB-1 to oxidize MeBr to CO2 is constitutive in cells regardless of the growth substrate. Addition of cell suspensions of strain IMB-1 to soils greatly accelerates the oxidation of MeBr, as does pretreatment of soils with low concentrations of methyl iodide. These results suggest that soil treatment strategies can be devised whereby bacteria can effectively consume MeBr during field fumigations, which would diminish or eliminate the outward flux of MeBr to the atmosphere.

scholarly journals Alternatives to Methyl Bromide for Strawberry Runner Plant Production

HortScience ◽  
2005 ◽  
Vol 40 (6) ◽  
pp. 1709-1715 ◽  
Author(s):  
Zahangir Kabir ◽  
Steven A. Fennimore ◽  
John M. Duniway ◽  
Frank N. Martin ◽  
Gregory T. Browne ◽  
...  
Keyword(s):  
Methyl Iodide ◽  
Methyl Bromide ◽  
High Elevation ◽  
Fruit Production ◽  
Environmental Risks ◽  
Plant Production ◽  
Soil Fumigant ◽  
Yield And Quality ◽  
Production Cycles ◽  
Strawberry Runner

For years, strawberry (Fragaria ×ananassa L.) runner plant nurseries have relied on methyl bromide (MB) fumigation of soil to produce healthy transplants. Methyl bromide, however, has been phased out due to its environmental risks. The potential for alternative fumigants to replace MB was evaluated at low and high elevation strawberry nurseries in California. The alternative fumigant iodomethane plus chloropicrin (IMPic) and a nonfumigated control (NF) were compared to methyl bromide plus chloropicrin (MBPic) at a low elevation nursery (LEN) and at a high elevation nursery (HEN) near Susanville, Calif. At a HEN near Macdoel, Calif., MBPic was compared to alternative fumigants IMPic, 1,3-dichloropropene plus chloropicrin mixture (Telone C35) followed by dazomet, chloropicrin (Pic) followed by dazomet and NF. Plants produced at the LEN were transplanted at the Macdoel HEN to measure the effects of soil fumigant history on plant health and runner plant production. Plants produced at both high elevation nurseries were evaluated for fruit yield and quality at two commercial fruit production sites in soils previously fumigated with MBPic or Pic. Runner plant production at the nurseries was similar in plots fumigated with either MBPic or alternative fumigants. All fumigation treatments had higher runner plant production than plants produced for two production cycles on NF soils. Generally, fruit yields from nursery plants produced on soils fumigated with IMPic, Pic followed by dazomet, or Telone C35 followed by dazomet, were similar to fruit yields from plants produced on MBPic fumigated soils. Overall, our results indicate that preplant soil treatments with IMPic, Pic followed by dazomet, and Telone C35 followed by dazomet, are potential alternatives to MBPic fumigation for strawberry runner plant nurseries. Fruit yields by plants in MBPic and Pic fumigated soils were comparable; however, they were more variable in Pic fumigated soils. Chemical names used: 1,3-dichloropropene (1,3-D), methyl bromide, methyl iodide (iodomethane), trichloronitromethane (chloropicrin), tetrahydro-3, 5-dimethyl-2 H-1,3,5-thiadiazine-2-thione (dazomet).

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