Cadmium alkyl halides

Cadmium alkyl and aryl halides, RCdX, as weU as cadmium allyls have been prepared by Grignard reactions but, as yet, have not realized any commercially important uses despite reactivity toward a number of organic and inorganic materials. 

Metal alkyls can be prepared in a simple manner from the main group halides (X = Cl, Br, I) and the appropriate alkyl Grignard reagent (RMgl) or the alkyllithium salt (RLi), as shown for the cadmium alkyls (Equation (2)).13 The elimination of impurities from the precursor source is of great importance, as any remaining impurities are invariably carried over into the growing semiconductor layers. Incorporation of impurities, even at levels as low as 1015 free carriers per cubic centimeter (one part in ca. 107), can drastically affect the electronic properties of the... 

Efforts to improve the efficient synthesis of organocadmium complexes by reaction of elemental cadmium with alkyl halides have been reported. Recent studies show that the presence of catalytic amounts of Cul and BuMgl in the reaction of alkyliodides with cadmium metal allows for the formation of 172a-c in high yield and high purity (Equation (58)).241... 

Mixed alkyl halide compounds result from the reaction of dialkylcadmium with cadmium halides. 

R2Cd compounds were first obtained by the direct reaction of cadmium metal with alkyl halides. Unfortunately, this method is limited and typically does not readily yield pure products. However, the direct method is facilitated by the use of highly activated cadmium slurries. " ... 

In support of the theory that the intermediate formation of alkyl esters occurs when dilute adds are used is the fact that olefins readily form addition compounds, because of thdr unsaturated nature, with certain substances and the claims that have been made for the hydrolysis of ethyl esters to ethanol. Almost 100 per cent yields of ethanol are daimed for the interaction of a mixture composed of 1 part of ethyl chloride and 10 parts of water by weight at 250° C. in the presence of catalysts composed of zinc, copper or cadmium sulfate or zinc chloride supported on active charcoal.58 In such processes as this, high yields can only be obtained by redrculation of the unconverted alkyl halide, or by the use of abnormally long times of contact at the low temperature, with removal of hydrochloric add. 

When alkyl halides react with metallic cadmium96,151 the primary product is probably the compound of type RCdX, as with the other elements of Group II, but so far such compounds have been obtained pure only by the action of anhydrous cadmium salts on dialkylcadmiums in anhydrous ether.152... 

Alkylpapaverinium salts, often called papaverine methochloride, etho-sulfate, etc., are prepared readily from the base and alkyl halides, sulfates, etc., by standard methods. Their reduction furnishes iV-alkyltetrahydro-papaverines (21, 27, 28). For example, iV-methylpapaverinium sulfate yields DL-laudanosine (XIII) on cathodic reduction (29) another publication records an almost quantitative yield of XIII by reduction of methyl-papaverinium chloride with zinc-cadmium alloy and acetic-formic acid (28). 

Acyl chlorides have been converted into unsymmetrical ketones by reaction with alkyl halide at a cadmium anode- - and by reaction with alkyl manganese iodide.Cyclopropylalkyl (or vinyl) ketones are formed in moderate yields by reaction of an acyl halide with cyclopropyltrimethylsilane. ... 

Zinc, Cadmium, and Mercury.—Slurries of finely divided Cd or Zn, formed by codeposition of the appropriate metal vapour with a solvent, are active enough to form organometallic reagents (presumed to be metal dialkyls) by reaction with simple alkyl halides. Not only a-bromoesters, but also a-bromoketones, can be reacted with Zn to give Reformatsky-like reagents. Subsequent reaction with an... 

Cadmium alkyls are useful reagents in organic chemistry for the conversion of acyl halides to ketones. They are prepared in situ by the direct addition of anhydrous CdCl2 to an ether solution of the Grignard reagent. 

Organocadmium compounds can be prepared from Grignard reagents or organo-lithium compounds by reaction with Cd(II) salts.180 They can also be prepared directly from alkyl, benzyl, and aryl halides by reaction with highly reactive cadmium metal generated by reduction of Cd(II) salts.181... 

The high reactivity of the cadmium metal powder is clearly demonstrated by the ready oxidative addition of a variety of alkyl and aryl halides. 

In terms of their chemical behavior, dialkylzinc compounds generally react to transfer alkyl groups to other metals. Dialkyls of cadmium are usually prepared by the reaction of a Grignard reagent with a cadmium halide. 

Reduction of RCOCI to RCHO. Sodium borohydride and this cadmium salt reduce acyl chlorides to aldehydes, but only in solvents such as DMF, DMA, and HMPT. DMF is essential, but the amount of DMF in the salt is sufficient. For the most part, yields are 50-90%. Aryl, alkyl, and benzylic halides do not react. Other functional groups (nitrile, nitro, ester, C=C) are also inert. 

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