Monoozonides of chloro-substituted conjugated dienes: preparation, stability, and some chemical reactions

1986 ◽  
Vol 64 (8) ◽  
pp. 1553-1559 ◽  
Author(s):  
Karl Griesbaum ◽  
Ashis R. Bandyopadhyay ◽  
Martin Meister
Keyword(s):  
Chemical Reactions ◽  
Conjugated Dienes ◽  
Double Bonds ◽  
Subsequent Reaction

The chlorodienes (E)-4-chloro-3-methyl-1,3-hexadiene (5a), (E)- and (Z)-4-chloro-2,3-dimethyl-1,3-hexadiene (5b/6b), (E,E)-5-chloro-4-methyl-2,4-heptadiene (5c), (4E)- and (4Z)-5-chloro-3,4-dimethyl-2,4-heptadiene (5d/6d), chloroprene (11a), and 2-chloro-3-methyl-1,3-butadiene (11b) are selectively ozonized at the non-chlorinated double bonds to give the corresponding monoozonides 7, 8, and 12. Further ozonolyses of the monoozonides of 5b and of 11b in methanol as well as epoxidation of the monoozonide of 5b and subsequent reaction of the resulting chloroepoxide with AgBF4 are described.

Mechanism of Rubber Vulcanization with Sulfur

1938 ◽  
Vol 11 (1) ◽  
pp. 107-130
Author(s):  
W. K. Lewis ◽  
Lombard Squires ◽  
Robert D. Nutting
Keyword(s):  
Natural Rubber ◽  
Temperature Coefficient ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Reaction Rate ◽  
Complex Behavior ◽  
Double Bonds ◽  
Irreversible Reaction ◽  
Sulfur Addition

Abstract THAT vulcanization of rubber with sulfur always involves a chemical reaction consisting in the addition of sulfur to the double bonds of the rubber molecule has been conclusively established (18, 28). The facts indicate that this addition of sulfur to rubber is an irreversible reaction (31). The temperature coefficient of the reaction is high, increasing about 2.65 fold per 10° C. at ordinary curing temperatures (31). Furthermore, the reaction is apparently exothermic (4, 24). It is noteworthy that catalysts are apparently necessary, since synthetic rubbers prepared from pure materials add sulfur slowly, if at all. The proteins and perhaps the resins in natural rubber undoubtedly serve as accelerators. The curves for combined sulfur vs. time of cure for typical mixes are shown in Figures 1 and 2. Figure 1 is taken from the data of Kratz and Flower (16); the composition and temperature of cure for this mix are shown in Cranor's Table I (9). Figure 2, curve 1, is from Table I of Eaton and Day (10), and curve 2 from data obtained in this laboratory (27, Table I). Superficial inspection of these curves shows extraordinary divergence of type. Figure 1 is a typical fadeaway curve, characteristic of most chemical reactions, where the reaction rate decreases with decreasing concentration of the reacting materials. Curve 1, Figure 2, is an entirely different type, where the rate of sulfur addition is constant until nearly 70 per cent of the initial sulfur has reacted. Curve 2, Figure 2, shows even more complex behavior. Again the rate is constant in the initial portions of the cure. However, following this period, the rate increases markedly but later falls off, approaching zero, to give an S-shaped eurve.

Structural Changes in Vulcanization of Buna-S

1946 ◽  
Vol 19 (3) ◽  
pp. 534-545
Author(s):  
Max H. Keck ◽  
La Verne E. Cheyney
Keyword(s):  
Natural Rubber ◽  
Chemical Reactions ◽  
Structural Changes ◽  
Double Bonds

Abstract In conclusion, the data presented here indicate that two types of chemical reactions take place during the vulcanization of Buna-S stocks of a specific type: (1) a combination with sulfur, which may or may not involve the double bonds in the polymer, and which may be similar in character to the primary vulcanization reaction of natural rubber; (2) a second reaction, presumably polymerization, which accompanies the first and is related to and possibly initiated by it, and which continues on over cure.

The Quantum Mechanics of Chemical Reactions Involving Conjugate Double Bonds

1933 ◽  
Vol 1 (8) ◽  
pp. 586-592 ◽  
Author(s):  
Henry Eyring ◽  
Albert Sherman ◽  
George E. Kimball
Keyword(s):  
Quantum Mechanics ◽  
Chemical Reactions ◽  
Double Bonds

Addition of thianthrene cation radical to non-conjugated dienes—Part II: Addition to two double bonds

2006 ◽  
Vol 27 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Bing-Jun Zhao ◽  
Henry J. Shine ◽  
John N. Marx ◽  
Anna T. Kelly ◽  
Cristina Hofmann ◽  
...  
Keyword(s):  
Cation Radical ◽  
Conjugated Dienes ◽  
Double Bonds

Chemical Reactions during Vulcanization. III

1942 ◽  
Vol 15 (3) ◽  
pp. 560-571
Author(s):  
E. A. Hauser ◽  
M. C. Sze
Keyword(s):  
Zinc Oxide ◽  
Double Bond ◽  
Chemical Reactions ◽  
Eleostearic Acid ◽  
Chemical Change ◽  
Membered Ring ◽  
Double Bonds ◽  
Tung Oil ◽  
Rate Of Reaction ◽  
Preceding Discussion

Abstract From the preceding discussion the following conclusions may be drawn: A. Vulcanization with Sulfur in General 1. Vulcanization with sulfur is fundamentally a chemical change involving activated sulfur and organic double bonds. 2. Sulfur must decompose from S8 (in the form of an eight-membered ring) to smaller molecular units, perhaps to S2 and S1 before it can be activated and react. 3. The ratio of atoms of sulfur combined to the number of double bonds lost is not restricted to one atom of sulfur for each double bond, but may have other values, which depend on the conditions and the reactions involved. B. Factice Formation 1. The rate of reaction of sulfur with tung and linseed oils is greatly influenced by small proportions of such agents as zinc oxide and mercaptobenzothiazole. 2. Combination of sulfur with the conjugated double bonds of the eleostearic acid in tung oil takes place at the terminal carbon atoms of the conjugated system, giving a typical 1,6-addition. 3. The following possible chemical reactions explain adequately the process of factice formation from tung and lineseed oil. Under different conditions different reactions predominate.

Synthesis of conjugated dienes and polyenes via diethyl phosphite promoted carbonyl olefination

RSC Advances ◽  
2014 ◽  
Vol 4 (74) ◽  
pp. 39497-39507 ◽  
Author(s):  
Ru Wang ◽  
Songlin Zhang
Keyword(s):  
Conjugated Dienes ◽  
Diethyl Phosphite ◽  
Double Bonds ◽  
One Pot ◽  
Carbonyl Olefination

A convenient one-pot protocol involving the transfer of carbon–carbon double bonds to obtain conjugated dienes and polyenes has been developed.

Anomalous ozone degradations of 1-chloro substituted conjugated dienes in methanol

1987 ◽  
Vol 65 (3) ◽  
pp. 487-490 ◽  
Author(s):  
Karl Griesbaum ◽  
Ashis R. Bandyopadhyay
Keyword(s):  
Conjugated Dienes ◽  
Double Bonds ◽  
Cleavage Reactions ◽  
Single Bonds

Diozonolyses in methanol of (E)-4-chloro-2,3-dimethyl-1,3-hexadiene (4a) and of (4E)-5-chloro-3,4-dimethyl-2,4-heptadiene (4b) resulted in complete cleavage of the double bonds and of the single bonds of the respective diene systems. The course of these anomalous cleavage reactions has been established by step-wise ozonolyses of these dienes, and by the identification of labile methoxy hydroperoxides as intermediates.

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