Organocadmium compounds

Organo-cadmium compounds are compounds in which the cadmium atom is bonded directly to the carbon atom of the organic functional groups. Such compounds include compounds CdR ₂ , Cd (R) X, in which R = alkyl or aryl radical, X = Hal, OR, SR, etc.

Content

Physical and chemical properties

Compounds Cd (Alk) ₂ are colorless flammable liquids with an unpleasant odor that decompose on heating above 150 ° C. Smoke in humid air, are not subject to self-ignition. Cd (Ar) ₂ compounds are colorless solids, insoluble in most organic solvents. Compounds Cd (R) Hal are formed in an equilibrium reaction, the equilibrium of which is strongly shifted to the right:

{\mathsf {CdR_{2}+CdHal_{2}\rightleftarrows 2Cd(R)Hal}}

{\ displaystyle {\ mathsf {CdR_ {2} + CdHal_ {2} \ rightleftarrows 2Cd (R) Hal}}}

Compounds also exist, such as methyloxymethylcadmium Cd (CH ₃ ) OCH ₃ and methylthiomethyl cadmium Cd (CH ₃ ) SCH ₃ , which are solid associates. The compounds [Cd (R) N ₃ ] OCH ₃ are thermally stable coordination polymers.

When heated and exposed to light, cadmium-organic compounds, with the exception of dimethylcadmium, decompose with the release of metallic cadmium. In air, they undergo oxidation, and dialkylcadmium forms peroxide compounds Cd (OOAlk) ₂ .

The reactivity of organo-cadmium compounds is lower than that of their organozinc analogues. So, organocadmium compounds do not interact with carbon dioxide and hydrogen halides ; react with aldehydes and ketones at a low rate, but in the presence of metal salts, the reaction rate increases. At the same time, they react with halogens and proton donor compounds - acids , alcohols , thiols , etc. Their reaction with anhydrides and acid chlorides leads to ketones:

{\mathsf {Cd(C_{2}H_{5})_{2}+2CH_{3}COCl\rightarrow CdCl_{2}+CH_{3}COC_{2}H_{5}}}

{\ displaystyle {\ mathsf {Cd (C_ {2} H_ {5}) _ {2} + 2CH_ {3} COCl \ rightarrow CdCl_ {2} + CH_ {3} COC_ {2} H_ {5}}}}

Receiving and applying

The synthesis of organocadmium compounds is carried out using Grignard reagents :

{\mathsf {CdCl_{2}+2CH_{3}MgCl\rightarrow Cd(CH_{3})_{2}+2MgCl_{2}}}

{\ displaystyle {\ mathsf {CdCl_ {2} + 2CH_ {3} MgCl \ rightarrow Cd (CH_ {3}) _ {2} + 2MgCl_ {2}}}}

Alkyl lithium is also used instead of alkyl magnesium halides. Organocadmium compounds are also capable of exchanging organic radicals:

{\mathsf {3Cd(C_{2}H_{5})_{2}+2B(CH_{2}CH{\text{=}}CH_{3})_{3}\rightarrow 3Cd(CH_{2}CH{\text{=}}CH_{3})_{2}+B(C_{2}H_{5})_{3}}}

{\ displaystyle {\ mathsf {3Cd (C_ {2} H_ {5}) _ {2} + 2B (CH_ {2} CH {\ text {=}} CH_ {3}) _ {3} \ rightarrow 3Cd ( CH_ {2} CH {\ text {=}} CH_ {3}) _ {2} + B (C_ {2} H_ {5}) _ {3}}}}

Electrochemical oxidation of cadmium in the presence of alkyl or aryl halides also relates to methods for the synthesis of organocadmium compounds. Compounds Cd (R) OR ′ and Cd (R) SR ′ are prepared by reacting Cd (Alk) ₂ with R′OH and R′SH, respectively. Compounds Cd (R) N ₃ are prepared by the reaction of CdR ₂ with ClN ₃ .

Organo-cadmium compounds are used to produce ketones from acid anhydrides and acid chlorides; to obtain hydroperoxides by oxidation of Cd (Alk) ₂ with atmospheric oxygen; as catalysts for polymerization, including together with titanium tetrachloride .

Toxicity

Like most cadmium compounds, its organic derivatives are toxic.

Literature

Knunyants I.L. et al. Vol . 2 Duffa-Copper // Chemical Encyclopedia. - M .: Soviet Encyclopedia, 1990 .-- 671 p. - 100,000 copies. - ISBN 5-85270-035-5 .