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. 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.

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.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document