The Unsaturation of Butadiene Rubbers. I

1949 ◽  
Vol 22 (2) ◽  
pp. 287-298
Author(s):  
A. A. Vasil'ev
Keyword(s):  
Intramolecular Cyclization ◽  
Degree Of Saturation ◽  
Double Bonds ◽  
Iodine Chloride ◽  
Iodine Bromide

Abstract 1. The data on the unsaturation of butadiene rubbers previously obtained by using the method based on the reaction with iodine bromide have been checked and confirmed with the aid of the reactions with pyridine sulfate dibromide and with iodine chloride. 2. The influence of various factors on the unsaturation of butadiene rubbers has been checked, and the possibility of estimating changes in unsaturation with the aid of the reaction with iodine bromide has been established. 3. The present investigation shows that, during the reaction between butadiene rubbers and halogens, it is impossible to attain a degree of saturation exceeding 85–90 per cent of the theoretical values. This is apparently due to the existence of intramolecular cyclization, to the presence of intermolecular connecting bridges, and possibly to the presence of double bonds resistant to halogenation or of conjugated double bonds in the molecules of these rubbers. The reaction with halogens offers no possibility of confirming these suppositions experimentally.

Stereocontrolled synthesis of rosuvastatin calcium via iodine chloride-induced intramolecular cyclization

2016 ◽  
Vol 14 (4) ◽  
pp. 1363-1369 ◽  
Author(s):  
Fangjun Xiong ◽  
Haifeng Wang ◽  
Lingjie Yan ◽  
Sheng Han ◽  
Yuan Tao ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Stereocontrolled Synthesis ◽  
Iodine Chloride ◽  
Rosuvastatin Calcium

A novel, stereoselective approach towards rosuvastatin calcium from the known (S)-homoallylic alcohol has been developed.

The cyclization of natural rubber

1963 ◽  
Vol 273 (1354) ◽  
pp. 345-359 ◽  
Keyword(s):  
Natural Rubber ◽  
Stannic Chloride ◽  
Double Bonds ◽  
Perbenzoic Acid ◽  
Infra Red ◽  
Iodine Chloride ◽  
Series Of Experiments ◽  
Average Size ◽  
Kinetics Of ◽  
Reaction In Solution

Several methods of measuring the unsaturation remaining in natural rubber after cyclization have been compared. Approximate agreem ent was obtained with the reagents, perbenzoic acid, phenyl iododichloride and ozone; iodine chloride gave high values. Perbenzoicacid is considered the most satisfactory of these reagents. The unsaturation in some cyclized rubber samples was found to be below 20% of that in the original rubber. This value is inconsistent with a cyclized rubber structure of single rings each involving two isoprene units and supports instead a polycyclic structure. This structure is also supported by some degradation experiments. Infra-red spectroscopy shows that the double bonds remaining after cyclization are not of the original trialkyl-substituted type. Use has been made of measurements of total unsaturation by means of perbenzoic acid and of trialkyl-substituted double bonds by infra-red spectrometry to investigate the kinetics of the cyclization reaction in solution and catalyzed by stannic chloride. All the results were accurately fitted by theoretical equations derived for a reaction proceeding in stepwise fashion along the rubber chains. The average size of the polycyclic structures formed during cyclization was found to be independent of both rubber and catalyst concentrations but to be markedly dependent on the temperature, varying in a series of experiments from approximately one and a half condensed rings at 110 °C to six rings at 60 °C. The rate of the reaction was first order in the rubber and second order in the catalyst.

Electrophilic ipso-Halocyclization of N-Phenyl-N-triflylpropiolamides Leading to 8-Halo-1-azaspiro[4.5]deca-3,6,9-trien-2-ones

Synthesis ◽  
2020 ◽  
Vol 52 (10) ◽  
pp. 1489-1497
Author(s):  
Gerhard Maas ◽  
Vito A. Fiore ◽  
Michael Keim ◽  
Roland Werz
Keyword(s):  
Amide Bond ◽  
Secondary Amines ◽  
Primary Amines ◽  
Iodine Chloride ◽  
Iodine Bromide

N-Phenyl-N-triflylpropiolamides react with iodine chloride or iodine bromide by an intramolecular electrophilic ipso-halocyclization/nucleophilic halide addition sequence to furnish cyclohexadiene-spiro-γ-lactams. These products can undergo cleavage of the amide bond with primary amines and of the N–Cspiro bond with secondary amines, leading to N-alkyl-2-iodo-3-phenylacrylamides and N-(4-halophenyl)-2-iodo-3-(2-triflylamino)phenylacrylamides, respectively.

Sulfur Bond in Vulcanizates Implications of Halogen Reactions

1947 ◽  
Vol 20 (3) ◽  
pp. 627-648
Author(s):  
S. R. Olsen ◽  
C. M. Hull ◽  
Wesley G. France
Keyword(s):  
Double Bond ◽  
Carbon Tetrachloride ◽  
Sulfur Atom ◽  
Side Reactions ◽  
Double Bonds ◽  
Vulcanized Rubber ◽  
Iodine Chloride ◽  
Allyl Sulfide ◽  
Sulfur Bond

Abstract 1. When iodine chloride is used for the determination of double bonds in sulfur-vulcanized rubber or GR-S, it undergoes side reactions induced by combined sulfur. 2. Bromine in carbon tetrachloride is believed to give a satisfactory measure of the double bonds in a rubber-sulfur vulcanizate dissolved in dichlorobenzene-chloroform mixture. 3. The relation of one double bond consumed per sulfur atom combined in the rubber-sulfur type vulcanizate was confirmed. 4. Organic accelerators (in the absence of metal activators) catalyze the combination of sulfur without altering the ratio of one double bond loss per sulfur atom combined. 5. The introduction of a metal oxide or soap, such as zinc, causes a different type of vulcanization, which results in less than one double bond consumed per sulfur atom combined. 6. The reactions of propyl sulfide, dodecyl sulfide, propyl disulfide, allyl sulfide, methallyl sulfide, and butylmethallyl sulfide with iodine chloride and with bromine, respectively, are described. 7. The behavior of rubber-sulfur vulcanizates resembles that of butylmethallyl sulfide in reactions with iodine chloride and bromine, respectively; this suggests an alkyl-allyl type sulfur bond. 8. The theory of vulcanization proposed by Armstrong, Little, and Doak, based on the α-methylenic concept of Farmer, is supported by the findings of this investigation.

The Influence of Structure on the Chemical Activity and Vulcanizability of Butadiene Polymers

1958 ◽  
Vol 31 (3) ◽  
pp. 569-580 ◽  
Author(s):  
B. A. Dogadkin ◽  
A. V. Dobromyslova ◽  
F. S. Tolstukhina ◽  
N. G. Samsonova
Keyword(s):  
Linear Function ◽  
Relative Content ◽  
Double Bonds ◽  
Initial Region ◽  
Linear Region ◽  
Kinetic Curves ◽  
Perbenzoic Acid ◽  
Ordinate Axis ◽  
Sulfur Addition ◽  
Iodine Chloride

Abstract 1. Differences between the chemical reactivities of 1,4- and 1,2-structures of butadiene are found in the reactions with perbenzoic acid, iodine chloride, and sulfur. 2. The interaction of perbenzoic acid with solutions of butadiene polymers is represented by kinetic curves with an initial region of a high rate, mainly corresponding to the reaction of the double bonds of 1,4-structure, and a final linear region of a low rate, characterizing the reaction of the double bonds in the vinyl side chains of 1,2-structure. By extrapolation of the linear region to the ordinate axis it is possible to determine the relative contents of the 1,4- (and hence of the 1,2-) structure in the polymer. 3. The kinetic curves for the interaction of the polymer solutions with iodine chloride are of analogous form. The initial region of the kinetic curve represents addition at the double bonds, while the linear region corresponds to the substitution reaction. By extrapolation of the linear region to the ordinate axis it is possible to determine the actual double bond content of the polymer. 4. The kinetic curves for iodine liberation are also of similar form ; here the linear region corresponds to the substitution reaction, and the initial region corresponds to the cyclization reaction. The amount of iodine liberated in this reaction is a linear function of the content of the 1,2-structure in the polymer. 5. Mainly the double bonds of the 1,4-structure react when sulfur interacts with the polymer solutions. The total rate of sulfur addition is a linear function of the content of the 1,4-structure. 6. The activation energy for sulfur addition increases with increasing relative content of the 1,2-structure in the polymer. 7. Formation of sulfur crosslinks in vulcanizates occurs mainly as the result of reactions in the 1,4 polymer structure. In consequence, the degree of crosslinking ΔE/ΔS is a linear function of the relative content of 1,4-structure in the polymer.

scholarly journals Polycentric binding in complexes of trimethylamine-N-oxide with dihalogens

RSC Advances ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 6131-6145
Author(s):  
Olga M. Zarechnaya ◽  
Aleksei A. Anisimov ◽  
Eugenii Yu Belov ◽  
Nikolai I. Burakov ◽  
Alexander L. Kanibolotsky ◽  
...  
Keyword(s):  
Ambient Conditions ◽  
Iodine Chloride ◽  
Monodentate Ligands ◽  
Iodine Bromide

Dihalogens readily interact with trimethylamine-N-oxide under ambient conditions. Stable 1 : 1 adducts were obtained in a case of iodine chloride and iodine bromide. Formally monodentate ligands are bound in a polycentric manner.

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