Olefinic halides

Olefin, n. olefin, olefine, -alkohol, m. olefinic alcohol, olefin alcohol, -haloid, n, olefin halide, olefinisch, a. olefinic. 

A triple bond may be formed by dehydrohalogenation of dihalides and olefinic halides of the general types RCX= CHj, RCH= =CHX, RCH= =CXR, RCHXCHjX, RCHXCHXR, RCHjCHX, and RCXjCHjR. The choice of a base depends somewhat on the position desired for the triple bond in the product. Sodium amide tends to rearrange the triple bond toward the end of the chain," and potassium hydroxide favors reverse isomerization toward the center of the chain,Although neither rearrangement is dependable from a synthetic standpoint, it is best to choose the base favoring the desired product. 

The condensation of saturated hydrocarbons with haloolefins in the presence of anhydrous aluminum chloride also results in the formation of alkyl halides, as in the preparation of l-chloro-3,4-dimethylpentane from isobutane and allyl chloride (40%). Under the same conditions, alkyl halides react with olefinic halides to give dihaloalkanes. unsym-Heptachloropropane is synthesized from tetrachloroethylene and chloroform (93%). ... 

Olefinic halides may be used as alkylating agents in the malonic ester synthesis. The olefinic malonic acids are decatboxylated to olefinic acids at lower temperatures (140-160°) than those employed for alkylmalonic acids. Examples include the conversion of 4-pentenylmalonic acid to 6-heptenoic acid (67%), allylmalonic acid to allylacetic acid (70%), and 2-cyclopentenylmalonic acid to 2-cyclopentenylacetic acid (99%)- ... 

Olefinic amino aciefe and alkoxy amino acids are obtained by this method from olefinic halides and halo ethers, respectively. 

Hydrocarbons, aromatic—Continued condensation with olefinic halides, 108... 

Even though there is an instance in which stereochemistry of the olefinic halide was not retained in the product [Eqs. (143) and (144) 296, but see also Ref 260], a number of coupling reactions [see Eqs. (123), (128), (129), (132), (134), (135), (139), (146), and (149)] verified that the process took place with virtually complete retention of configuration of olefinic substrates which, no doubt, is an outstanding feature of this method. 

The electron-withdrawing group is absolutely necessary for the acceptance of electron density from a nucleophile. Simple olefinic halides, RCH=CH-X, are very unreactive because there is no good place to put the electrons from the nucleophile. 

The efifect of electrocatalyst and operating conditions on selectivity were examined recently for the reduction of olefinic halides to saturated halides or cleavage products (hydrogenation versus hydrogenolysis) 31. These two steps proceed in parallel at different rates on various electrocatalysts. Thus, the ability for double bond reduction decreases in the order Pd Ru > Ag > Pt, although the overall rate is about the same on Pd and Pt (cf. Table VI). Figure 24 shows the extensive variation of reaction specificity with cathode potential as well as the smaller effect of electrolyte concentration. Similar behavior is exhibited by other halides and electrodes 31. ... 

Electrochemical reduction of organic halides has attracted considerable attention. Conventional electroreduction on mercury results only in cleavage of the carbon-halogen bond without reduction of unsaturates (52). However, Cd, Zn, Sn, and Cu form also ethane from olefinic halides 370). An EEC mechanism has been proposed for these reductions [i.e., two electrochemical steps (E) and a chemical (C) step, consecutively] involving a direct electron transfer to the halide and formation of a carbanion 32) ... 

A further example of the cyclization of a highly functionalized carbohydrate derivative is given by the preparation of polyhydroxylated cyclopentanes from halogenated carbohydrates19. Treatment of the olefinic halides with tributyltin hydride affords two isomeric products. 

Vinylic halides, allylic halides, homoallylic halides and other olefinic halides. 

Nickel bisphosphine complexes are used as catalysts in cross-coupfing of aromatic and olefinic halides with Grignard reagents. Kumada and co-workers [69] reported a cross-coupling reaction... 

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