Aluminum hydrides reactions with

Lithium aluminum hydride, reaction with aldehydes, 610 reaction with carboxylic acids. 611-612... 

In most cases the identity of the reactive reducing species is not known with certainty. For example, the species initially formed by the reaction of lithium aluminum hydride (LAH) with alcohols may not be stable with respect to disproportionation. The degree of association of reducing species may be an important unknown factor in a particular case. Processes other than disproportionation or association may also make it difficult to predict the structure of the reagent formed from the reaction of LAH with sterically hindered alcohols (see Sect. II-A-1). 

Elaboration of 2-isoxazolines via their 4-endo-anions has been studied as a method to synthesize y-amino alcohols (78TL3129,3133,81AG(E)601,603). When the 5-methyl-3-phenyl-2-isoxazoline (527) was deprotonated with LDA/HMPA and methylated with methyl iodide, the tra 5-4,5-substituted isoxazoline (528) was formed predominantly (trans-.cis = 12 1). Reduction of this isoxazoline with lithium aluminum hydride proceeded with steric approach control to provide a diastereomeric mixture of y-amino alcohols (529, 530 Scheme 116). The 5-substituent was found to exhibit a greater steric influence on this reaction than the 4-substituent. 

On the basis of what we have already learned about the reactions of lithium aluminum hydride with aldehydes and ketones (Chapter 18) and the mechanisms presented so far in this chapter, we can readily predict the product that results when hydride reacts with a carboxylic acid derivative. Consider, for example, the reaction of ethyl benzoate with lithium aluminum hydride. As with all of the reactions in this chapter, this reaction begins with attack of the nucleophile, hydride ion, at the carbon of the carbonyl group, displacing the pi electrons onto the oxygen (see Figure 19.7). Next, these electrons help displace ethoxide from the tetrahedral intermediate. The product of this step is an aldehyde. But recall from Chapter 18 that aldehydes also react with lithium aluminum hydride. Therefore, the product, after workup with acid, is a primary alcohol. 

It has been involved in many industrial explosions. Explodes on contact with aluminum + barium nitrate + potassium nitrate + water. Forms explosive mixtures with aluminum powder + titanium dioxide, ethylene glycol (240°C), cotton lint (245°C), furfural (270°C), lactose, metal powders (e.g., aluminum, iron, magnesium, molybdenum, nickel, tantalum, titanium), sulfur, titanium hydride. Reaction with ethanol + heat forms the explosive ethyl perchlorate. Violent reaction or ignition under the proper conditions with aluminum + aluminum fluoride, barium chromate + mngsten or titanium, boron + magnesium + silicone rubber, ferrocenium diammine-tetrakis(thiocyanato-N) chromate(l —), potassium hexacyanocobaltate(3—), A1 +... 

Substrates covered are listed in the index page. Most investigators have worked with the complex hydrides of boron and aluminum therefore reactions with these form the principal part of the discussion. Some work with other organometallic hydrides and complex hydrides of some transition metals is also described. 

Oxymercuration of simple alkyl- and acyl-substituted cyclopropenes generally results in ring opening.Addition of mercury(II) acetate to 3-methyl-3-phenylcyclopropene, however, gave a low yield of a cyclopropane containing organomercury compound (15-20%), which was converted into an isomeric mixture of 1 -methoxy-2-methyl-2-phenylcyclopropanes by reduction with lithium aluminum hydride. Reaction of 5 with mercury trifluoroacetate in methanol and then sodium hydroxide led predominantly to one cylopropane. ... 

Finally, bis(dialkylamino)aluminum hydrides react with unsaturated carbon-carbon bonds. In the presence of catalytic amounts of (h -C5H5)2TiCl2 the reaction is complete within 10 min (93 % yieldf - ... 

Ziegler and Gellert (6) in 1949 showed that aluminum hydride reacts with ethylene at 60-80 °C to yield triethylaluminura. At 100-120 C reaction with additional ethylene leads to formation of higher alkyls of aluminum (Reaction 1). At temperatures above 120 C higher aluminum alkyls react with ethylene through a... 

DIMETHYL ETHER (115-10-6) CjHjO Highly flammable, peroxidizable gas. Forms ejqjlosive mixture with air [explosion limits in air (vol %) 3.4 to 18.0 flash point -42°F/-41°C autoignition temp 662°F/350°C Fire Rating 4]. May be heat-and shock-sensitive. Able to form unstable peroxides on prolonged exposxure to air. Violent reaction with oxidizers, aluminum hydride lithium aluminum hydride. Incompatible with strong acids, metal salts. On small fires, use dry chemical powder (such as Purple-K-Powder), dry sand, or COj extinguishers. 

Although the low-pressure polymerization of ethylene in the presence of a Ziegler catalyst is a catalytic process, the growth reaction of aluminum hydride or a corresponding alkylaluminum with ethylene occurs as an organometallic synthesis 29 at 60-80° aluminum hydride reacts with ethylene to yield tri-ethylaluminum ... 

By methods analogous to those cited in the section on hippeastrine, homolycorine (LXVII) afforded a diol upon reduction with lithium aluminum hydride. Treatment with p-toluenesulfonyl chloride followed hy iodide ion gave pluviine jS-methiodide (LXVIII) (mp 232°-233°). This salt was not identical with the known pluviine a-methiodide (mp 259°-261°). Structure proof for LXVJII rests on the pyrolysis of its methochloride to pluviine and anhydromethylpseudolycorine. This interconversion relates the asymmetric centers of pluviine to those of homolycorine and lycorenine. Comparable reactions with a- and j3-dihydrohomolycorine (LXIX and LXX, respectively) converted these compounds to the metho salts of a- and )8-dihydropluviine (LXXI and... 

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