Magnesium compounds halides

These c-complexes have been less extensively studied than the r 3-allyltitanium derivatives. r 1 -Allyltitanocenes can readily be prepared from the corresponding magnesium compounds by reaction with Cp2TiCl2 or by reaction of preformed r 3-allyltitanium complexes with but-2-enyl halides [36]. Crotyl-type reagents, which are accessible only in the E-iso-meric form, add to aldehydes with an anti selectivity (Scheme 13.17). 

Coupling of acetylenes and halides, copper-promoted, 50,100 Cuprous chloride, reaction with an organo-magnesium compound, 50,98... 

Asymmetrically substituted allyl magnesium compounds often react to yield products derived from both the parent allyl halide and the corresponding aUylic isomer, in varying relative yields . Depending on the arrangement of the substituents, cis and trans... 

In practice, the metal in the form of ribbon or borings is added gradually to a solution of well dried alkyl or aryl halide in dry ether a brisk reaction usually takes place, owing to the formation of the magnesium compound of type B.Mg.X (X=01,Br,I). 

In addition to the magnesium compounds, lithium alkyls are versatile reagents that also function as alkyl group transfer agents. Lithium alkyls are prepared by the reaction of lithium with an alkyl halide using benzene or petroleum ether as a solvent ... 

As in the case of aldehydes, Barbier reactions of magnesium, organic halide and ketone can be an alternative to the reactions via preformed organomagnesium compounds [18, 53],... 

This compound is prepared in an ether solution, and it is believed that the ether enters into the product and that the formula is probably not the simple magnesium alkyl halide, but is... 

The first organic compound of boron was isolated by Frankland in 1862, by the interaction of zinc methyl and triethyl borate. This method and the use of zinc alkyls with boron trichloride was continued until the discovery of the Grignard reagent. In 1900 boron tri-methyl was prepared by the action of magnesium methyl iodide on trimethyl borate, and in 1921 a number of boron trialkyls were obtained by the interaction of magnesium alkyl halides and boron trifluoride. Of the derivatives of the type RgB, boron trimethyl is a gas, spontaneously inflammable in air boron triethyl, a spontaneously inflammable liquid whilst the higher members of the series are liquids, readily oxidised when exposed to air. The metl yL fpd ethyl derivatives combine with ammonia to foriii IliS type I BOH only... 

Table XIII. of the Appendix gives a list of compounds prepared by the following general method, together with their physical constants, Three times the ealeulated quantity of magnesium alkyl halide is used, and after the introduction of the tin alkyl halides the mixture is boiled under reilux for two hours, the etlier removed, and the residue baked on the water-buth lor one liour. After cooling, ether is added, and the whole deosed with water. Mixed tin tetra-alkyls are converted into inixed tin trialkyl bromides of the type R R SnX by the action of bromine at - 40° to —30° C., ati alkyl group being split out, this resembling the bromination of lead alkyls.

Lead tetra-alkyls containing one or two secondary radicles can easily be obtained by the action of lead alkyl mono- or dihalides on secondary magnesium alkyl halides, win 1st those containing three secondary radicles are derived ] )rimaril,y from the tctra-alkyls. Table XX. of the Appendix gives a list of these compounds, together with their physical constants. 

Magnesium compounds hydrate readily, and anhydrous magnesium halides form addition compounds with aldehydes, ketones and ethers, which are structurally similar to those of Be. Otherwise its complexes are few and unstable. 

Before lithium aluminium hydride was available as a reducing agent, the tin hydrides were prepared by treating the stannyl-lithium or stannyl-sodium compounds with ammonium halides in liquid ammonia.31 More recently, stannyl-magnesium compounds have been used in the same way (equation 15-14).32... 

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