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.

scholarly journals Iodine value of tung biodiesel fuel using Wijs method is significantly lower than calculated value

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Toshisada Suzuki ◽  
Kazuki Sumimoto ◽  
Kazuhiro Fukada ◽  
Takeshi Katayama
Keyword(s):  
Double Bond ◽  
Iodine Value ◽  
Eleostearic Acid ◽  
Southern China ◽  
Average Molecular Weight ◽  
Atomic Radius ◽  
Biodiesel Fuel ◽  
Double Bonds ◽  
Tung Oil ◽  
Wijs Method

AbstractThe tung tree (Vernicia fordii) is a non-edible oil plant native to southern China and was introduced in Japan in the nineteenth century. The tree produces tung oil, which is composed of approximately 80% α-eleostearic acid (9c, 11t, 13t-octadecatrienoic acid), 7% linoleic acid, and 6% oleic acid. Tung oil may be a non-edible source of biodiesel fuel (BDF) production. The iodine value (IV) is one of parameters to guarantee BDF quality, and the most common method for the determination of IV is the Wijs method. The IV can be calculated from the average molecular weight and the number of double bonds from the GC–MS data. In this study, the IVs of olive, castor, soybean, linseed, and perilla BDF using the Wijs method were found to be almost the same as the calculated IV. On the other hand, the IV of tung BDF by the Wijs method indicated a significantly lower value than that of the calculated value. To determine the cause of this discrepancy, the samples before and after halogenation using the Wijs method, were analyzed by 1H NMR. The conjugated double bond signals did not disappear, and a broad double bond signal remained in the tung BDF spectrum after halogenation. These results demonstrated that iodine, with a large atomic radius, could not react completely with the three conjugated double bonds in α-eleostearic acid. Therefore, the IV of tung BDF was significantly lower than the calculated value.

Sample Stability: A Suggested Definition and Medthod of Determination

1976 ◽  
Vol 22 (12) ◽  
pp. 2045-2045
Author(s):  
Ralph E Thiers ◽  
Gaw T wu ◽  
Allen H Reed ◽  
Lawrence K Oliver
Keyword(s):  
Double Bond ◽  
Membered Ring ◽  
Double Bonds ◽  
Test Statistic ◽  
Original Magnification ◽  
Letter To The Editor ◽  
Sample Stability ◽  
Single Bonds

Abstract Volume 22 p 52, colunm 1: In two palces, "γ-GT/ml" should read "γ-GT/CC." In Figures 2 through 4 in this paper, the "X800" in the legend refers to the original magnification. p 179: In Table 2, in the —20 °C experiment, the "test statistic" of samples 5 through 18 should be more negative by 0.5 and that of sample 24 should be —7.0 rather then —5.0. These change do not affect the conclusions. p 197, column 1: In the first full paragraph, reference "(2)" should read "(21)." p 777: In Figure 1, structures B and C should not contain an endocyclic double bond (structure A is correct)-i.e., the double bonds at the tops of the seven membered ring should be single bonds. p 833: Corrections to this Table are detailed in a Letter to the Editor, p 1751, q.v. p 1324: The drawing for Figure 2 has been interchanged with the drawing in the upper half of Figure 9, p 1327. p 1427: Richard S. Schifreen should be listed as an author. p 1745, column 1: The [3H]cortisl belongs to ref. 1, and was not supplied by Diagnostic Products Corp. p 1751, column 3, first paragraph: 9.7 mg/liter should read 0.7 mg/liter.

scholarly journals THE STEREOSELECTIVE ADDITION OF DIHALOCARBENES TO cistrans, trans-CYCLODODECA-1,5,9-TRIENE AND THE SYNTHESIS OF CYCLOTRIDECANONE

1966 ◽  
Vol 44 (9) ◽  
pp. 1021-1026 ◽  
Author(s):  
H. Nozaki ◽  
S. Katô ◽  
R. Noyori
Keyword(s):  
Double Bond ◽  
Membered Ring ◽  
Ring Cleavage ◽  
Addition Reactions ◽  
Double Bonds ◽  
Olefinic Bond ◽  
Stereoselective Addition

The addition reactions of dibromo- and dichloro-carbenes to cis,trans,trans-cyclododeca-1,5,9-triene (I) followed a stereoselective scheme analogous to that of other reagents forming a three-membered ring on addition to an olefinic bond. The carbenes attacked preferentially one of the trans double bonds of I and then added to the cis double bond of the resulting bicyclic cis,trans dienes. Skattebøl's ring cleavage of dihalocarbene adducts of cis-cyclo-dodecene as well as of the monoadducts of I, followed by several steps, gave cyclotridecanone in fairly good yields.

Chemical Reactions during Vulcanization

1940 ◽  
Vol 13 (1) ◽  
pp. 65-73
Author(s):  
E. A. Hauser ◽  
J. R. Brown
Keyword(s):  
Tensile Strength ◽  
Double Bond ◽  
Chemical Reactions ◽  
Infrared Absorption ◽  
Sulfur Compound ◽  
Double Bonds ◽  
Absorption Data ◽  
Dehydrogenation Reaction ◽  
Excess Loss ◽  
Sulfur Vulcanization

Abstract Direct addition or bridging of sulfur seems to occur at the double bonds of the rubber in sulfur vulcanization without accelerators (Figure 5, a and b). In accelerated stocks the fact that sulfur combines in excess of one atom of sulfur saturating one double bond of the rubber hydrocarbon suggests that sulfur may also combine in a dehydrogenation reaction (Figure 5, c), and that this type of sulfur linkage is most effective in producing high tensile strengths. The excess loss in unsaturation on overcure indicates that direct polymerization without sulfur (Figure 5, d), as well as reactions of oxygen at the double bonds, may occur after most of the sulfur has combined, but that these chemical changes are not definitely associated with changes in the vulcanized structure as measured by tensile strength. In the vulcanization of a simple rubber-sulfur compound, infrared absorption data indicate that oxygen is combining with the rubber during overcure to produce a degradation in the hydrocarbon structure which is accompanied by a decided loss in tensile strength.

MNDO CI study of the photoisomerization of pentadieniminium

1990 ◽  
Vol 55 (12) ◽  
pp. 2874-2879 ◽  
Author(s):  
Peter Ertl
Keyword(s):  
Schiff Base ◽  
Double Bond ◽  
Configuration Interaction ◽  
Mndo Method ◽  
Double Bonds

Photoisomerization mechanism in model retinal-like protonated Schiff base pentadieniminium was investigated by using MNDO method with configuration interaction. Isomerizations around various double bonds were studied and twisted biradical geometries in S0 and S1 states were optimized. Photoisomerization proceeds exclusively around the central double bond where the twisted S1 state is strongly stabilized and the S0-S1 gap is minimal.

scholarly journals Tung Oil-Based Production of High 3-Hydroxyhexanoate-Containing Terpolymer Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate-co-3-Hydroxyhexanoate) Using Engineered Ralstonia eutropha

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1084
Author(s):  
Hye Soo Lee ◽  
Sun Mi Lee ◽  
Sol Lee Park ◽  
Tae-Rim Choi ◽  
Hun-Suk Song ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Eleostearic Acid ◽  
Fossil Fuels ◽  
Ralstonia Eutropha ◽  
Wild Type ◽  
Medical Field ◽  
Tung Oil ◽  
Medium Chain Length ◽  
Partial Harvesting ◽  
Biodegradable Properties

Polyhydroxyalkanoates (PHAs) are attractive new bioplastics for the replacement of plastics derived from fossil fuels. With their biodegradable properties, they have also recently been applied to the medical field. As poly(3-hydroxybutyrate) produced by wild-type Ralstonia eutropha has limitations with regard to its physical properties, it is advantageous to synthesize co- or terpolymers with medium-chain-length monomers. In this study, tung oil, which has antioxidant activity due to its 80% α-eleostearic acid content, was used as a carbon source and terpolymer P(53 mol% 3-hydroxybytyrate-co-2 mol% 3-hydroxyvalerate-co-45 mol% 3-hydroxyhexanoate) with a high proportion of 3-hydroxyhexanoate was produced in R. eutropha Re2133/pCB81. To avail the benefits of α-eleostearic acid in the tung oil-based medium, we performed partial harvesting of PHA by using a mild water wash to recover PHA and residual tung oil on the PHA film. This resulted in a film coated with residual tung oil, showing antioxidant activity. Here, we report the first application of tung oil as a substrate for PHA production, introducing a high proportion of hydroxyhexanoate monomer into the terpolymer. Additionally, the residual tung oil was used as an antioxidant coating, resulting in the production of bioactive PHA, expanding the applicability to the medical field.

A stereospecific synthesis of trisubstituted double bonds

1970 ◽  
Vol 23 (4) ◽  
pp. 813 ◽  
Author(s):  
AJ Birch ◽  
B McKague
Keyword(s):  
Double Bond ◽  
Stereospecific Synthesis ◽  
Considerable Proportion ◽  
Double Bonds ◽  
Steric Configuration

An aspect of the synthesis of sterically defined trisubstituted double bonds is discussed. Metal-ammonia reductions of hydropyridinium salts such as (1 ; R, R' = H or Me) result in allylic fissions, with a considerable proportion of double bond retention in its original situation and complete retention of the original steric configuration in that position.

Chlorination of Natural Rubber in Solution with Gaseous Chlorine

1953 ◽  
Vol 26 (4) ◽  
pp. 902-911 ◽  
Author(s):  
C. S. Ramakrishnan ◽  
D. Raghunath ◽  
J. B. Pande
Keyword(s):  
Double Bond ◽  
Natural Rubber ◽  
Cyclization Reaction ◽  
Double Bonds ◽  
Chlorine Atoms ◽  
Reaction Stage ◽  
Stage 1 ◽  
Additive Reaction

Abstract The chlorination of rubber solutions by gaseous chlorine was followed by isolating the partially chlorinated products and preparing their ozonides. The ozonides were hydrolyzed, and the acids and aldehydes formed on hydrolysis were determined. By a comparison with the amounts of acids and aldehydes obtained from ozonides of unreacted rubber, the amount of residual isoprenic double bonds present was found. The loss of double bonds attending the introduction of chlorine atoms into the molecule of rubber indicates four definite stages in chlorination : (1) initial substitutive attack by chlorine, with concomitant cyclization, resulting in a loss of one double bond between two isoprenic units, (2) substitution, (3) additive reaction, and (4) essentially substitution. Chlorination of aged rubber solutions differs from the above in that the cyclization reaction (stage 1) seems to be absent.

The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

1943 ◽  
Vol 16 (4) ◽  
pp. 841-847
Author(s):  
A. Gantmacher ◽  
S. Medvedev
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Raman Spectra ◽  
Polymer Molecule ◽  
Polymerization Process ◽  
High Polymer ◽  
Single Bond ◽  
Double Bonds ◽  
Continuous Background ◽  
Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

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