Reactions of Magnesium Hydride and Diethylmagnesium with Olefins¹

Abstract

removed by filtration, washed with ether, and air-dried. The dry solid melted at 170-172' and weighed 0.75 gram (71%). Evaporation of the solvent on the steam bath gave an additional 50 to 100 milligrams of yellow solid (m.p. 165-168').The crude product waa recrystallized from 96y0 ethanol and melted a t 171.0-172.0°.Anal. Calcd. for C1aHlaNO,: 63.15% C, 5.30% H. Found:Acid hydrolysis of ethyl 9-benzoxazolylpyruvate methylation product. A mixture of 1 gram of the methylation product described in the preceding section and 25 ml. of 20% hydrochloric acid was heated under reflux for 6 hr. The colorless acidic solution was chilled in an ice bath and neutralized with eodium bicarbonate. A white precipitate formed which darkened rapidly on standing in contact with the aqueous solution. The precipitate, when dried, weighed 0.8 g. The crude material was crystallized from a benzene-petroleum ether mixture and sublimed in Vacuo (at 1 mm. of mercury and 75-85'). The colorless, crystalline product melted a t 63.25% C, 5.467'0 H. 93-95'. The hydrolysis product was proved to be o-methylaminophenol by comparison of melting points and mixture melting points with an authentic sample.27 the authors are grateful for helpful discussions. BETHLEHEM, PA. (27) The melting points were determined simultaneously in the same apparatus, since there is considerable disagreement in the literature regarding the correct melting point of o-methylaminophenol, [CONTRIBUTION FROM THEl RESEARCH AND DEVELOPMENT LABORATORIES O F THE ETHYL CORPOR.4TIOS ]Magnesium hydride was found to add to ethylene, 1-octene, and isobutylene to form the magnesium-carbon bond in low yields. The extent of the reaction appears to be dependent upon the surface or form of the hydride and is limited by the occurrence of side and consecutive reactions, such as solvent cleavage, carbonization, and chain growth. Evidence was obtained for catalysis of the hydride-alkylation reaction by organometallics, such as alkylaluminum and alkylboron compounds. Relevant to the chain growth reaction, it was found that a mixture of magnesium hydride and triethylboron in diethyl ether catalyzed the low-pressure polymerization of ethylene at room temperature to form solid polyethylene.Diethylmagnesium was found to be considerably more reactive than magnesium hydride toward olefins. With ethylene in diethyl ether, 25-35% conversion of diethylmagnesium to n-butylmagnesium compounds was obtained. In hydrocarbon solvents, complete consumption of the diethylmagnesium occurred, with the formation of hydrocarbons containing ten or more carbon atoms per molecule.

Reactivity of a Molecular Magnesium Hydride Featuring a Terminal Magnesium–Hydrogen Bond

“…The presence of (somewhat labile) Al i Bu 3 in the molecule obviously complicates the reaction considerably. While nonpolar double bonds do not undergo insertion (i.e., hydromagnesiation), , polar substrates such as aldehydes and ketones smoothly reacted with 1 to give the expected alkoxides. CO 2 gave the formate, which exhibits a rather unusual κ O ,κ O ′ coordination .…”

Iron‐Catalysed Hydrofunctionalisation of Alkenes and Alkynes

“…[140] The hydromagnesiation reaction of olefins 267 can be an attractive alternative to standard methods for the synthesis of Grignard reagents 268 if the required alkyl or vinyl halides are not readily synthesised or if they contain functional groups incompatible with Grignard reagent formation. The reaction of MgH 2 with alkenes is inefficient, [141] and although titanium and zirconium salts can be used to catalyse this reaction, [142] the most common approach is to use a Grignard reagent 269 bearing b-hydrogen atoms as a superficial source of "HÀMgX" (Scheme 59 A). An equivalent of alkene 270 is produced as a by-product, and thus the reaction is generally reversible and thermodynamically driven.…”

Magnesiumorganische Innerkomplexe, Teil II [1]. Ethyl(dialkylaminoalkyl)- und Ethyl(4-alkoxybutyl)magnesium-Verbindungen / Organomagnesium Inner Complexes, Part II [1]. Ethyl(dialkylaminoalkyl)- and Ethyl(4-alkoxybutyl)magnesium Compounds

“…Es ist bekannt, daß M gEt2 (hergestellt durch D isproportionierung von EtM gX) mit Ethylen unter Einschub weniger M oleküle in die M g-C-Bindung reagiert [9].…”