15.2 Nitro compounds without double bonds conjugated with the NO2 group

2005 ◽  
pp. 230-237
Author(s):  
A. Berndt
Keyword(s):  
Nitro Compounds ◽  
Double Bonds

Studies in the Vulcanization of Rubber. VII. Unsaturation of Rubber Vulcanized with Nitro Compounds and Benzoyl Peroxide

1937 ◽  
Vol 10 (4) ◽  
pp. 735-742
Author(s):  
John T. Blake ◽  
Phillip L. Bruce
Keyword(s):  
Benzoyl Peroxide ◽  
Chemical Reaction ◽  
Nitro Compounds ◽  
Unsaturated Hydrocarbon ◽  
Secondary Reaction ◽  
Double Bonds ◽  
Decomposition Products ◽  
Vulcanized Rubber ◽  
Chemical Theory

Abstract RUBBER is primarily an unsaturated hydrocarbon. Sulfur adds to its double bonds during vulcanization to form soft and hard vulcanizates. In the formation of soft vulcanized rubber, unsaturation is reduced several per cent by the chemical addition of sulfur. Spence and Scott (10) showed that the proportion of combined sulfur corresponds exactly to the decrease in unsaturation, and therefore that sulfur combination consists entirely of addition to the double bonds of rubber. The studies of one of the authors (1) on the vulcanization of rubber with nitro compounds indicate that these substances or their decomposition products combine with rubber. Van Rossem (8) also showed that vulcanization with benzoyl peroxide is accompanied by a decrease in extractable material, indicating that either the reagent or its decomposition products combine chemically with the rubber. The natural expectation would be that addition to the double bonds occurs and that the unsaturation decreases correspondingly. Van Rossem's proposed mechanism for the vulcanization with benzoyl peroxide would involve no change in unsaturation. Fisher and Gray (2) applied Kemp's method (4) in determining the iodine numbers of a single vulcanizate of each of four compounds. The vulcanizing agents involved were m-dinitrobenzene, trinitrotoluene, and benzoyl peroxide. Their unsaturation values agreed closely with calculated values for the unvulcanized compounds. They concluded from their results that “Ordinary vulcanization is an unknown or undetermined type of change in the hydrocarbon involving no change in the unsaturation and that chemical union of sulfur is a secondary reaction.” If true, this evidence is a serious blow to the chemical theory of vulcanization which postulates that a chemical reaction is essential for the process. The present paper offers evidence that the vulcanization of rubber with these reagents does involve change in its unsaturation.

Synthesis of fine chemicals by the conjugate addition of nitroalkanes to electrophilic alkenes

2006 ◽  
Vol 78 (10) ◽  
pp. 1857-1866 ◽  
Author(s):  
R. Ballini ◽  
L. Barboni ◽  
G. Bosica ◽  
D. Fiorini ◽  
A. Palmieri
Keyword(s):  
Michael Reaction ◽  
Conjugate Addition ◽  
Building Blocks ◽  
Nitro Compounds ◽  
Fine Chemicals ◽  
Double Bonds ◽  
Aliphatic Nitro Compounds ◽  
Michael Adducts

Several aliphatic nitro compounds have been employed as stabilized carbanions in the conjugate addition to a variety of electron-poor alkenes (Michael reaction). Depending on the nature of the alkene, new carbon-carbon single or double bonds can be generated. However, all the Michael adducts can be efficiently utilized as key building blocks for the synthesis of a huge array of fine chemicals, including homo- and heterocyclic structures.

Gold liposomes

1996 ◽  
Vol 54 ◽  
pp. 898-899
Author(s):  
James F. Hainfeld
Keyword(s):  
Direct Methods ◽  
Important Class ◽  
Double Bonds ◽  
Membrane Phospholipids ◽  
Essential Ingredient ◽  
Lipid Structures

Lipids are an important class of molecules, being found in membranes, HDL, LDL, and other natural structures, serving essential roles in structure and with varied functions such as compartmentalization and transport. Synthetic liposomes are also widely used as delivery and release vehicles for drugs, cosmetics, and other chemicals; soap is made from lipids. Lipids may form bilayer or multilammellar vesicles, micelles, sheets, tubes, and other structures. Lipid molecules may be linked to proteins, carbohydrates, or other moieties. EM study of this essential ingredient of life has lagged, due to lack of direct methods to visualize lipids without extensive alteration. OsO4 reacts with double bonds in membrane phospholipids, forming crossbridges. This has been the method of choice to both fix and stain membranes, thus far. An earlier work described the use of tungstate clusters (W11) attached to lipid moieties to form lipid structures and lipid probes.

Stereoselective Synthesis 1 Stereoselective Reactions of Carbon—Carbon Double Bonds

2011 ◽  
Author(s):  
J. G. de Vries ◽  
K. Muñiz ◽  
G. Franciò ◽  
W. Leitner ◽  
P. L. Alsters ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Double Bonds ◽  
Stereoselective Reactions
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