Preparation of Lithium Hydride

Preparation of Lithium Hydride. Perform the experiment in the presence of your instructor ) Assemble an apparatus as shown in 

When the absorption of the hydrogen stops (how can this be determined ), cool the apparatus to room temperature in a hydrogen atmosphere. Write the equation of the reaction. Extract the boat from the tube. What is the colour of the product See how lithium hydride reacts with water. What is the nature of the bond in a lithium hydride molecule  

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Benzo-l,2-dithiole-3-thiQne (77b) reacts with lithium in THF to produce a complex which is useful in the preparation of lithium hydrides (78BEP867155). Various 3-(4-dimethyl-aminophenyl-l,2-dithiolylium salts (175) and other dithiolylium salts function as dyes for polyacrylonitrile and have been proposed as sensitizers for organic photoconductors (64USP3158621, 66USP3299055, 71USP3530145, 71USP3575968). 

Use Polymerization of isoprene and butadiene intermediate in preparation of lithium hydride rocket fuel component metalating agent. 

Preparation. Commercial manufacture of LiAlH uses the original synthetic method (44), ie, addition of a diethyl ether solution of aluminum chloride to a slurry of lithium hydride (Fig. 2). 

Uses. The largest use of lithium metal is in the production of organometaUic alkyl and aryl lithium compounds by reactions of lithium dispersions with the corresponding organohaHdes. Lithium metal is also used in organic syntheses for preparations of alkoxides and organosilanes, as weU as for reductions. Other uses for the metal include fabricated lithium battery components and manufacture of lithium alloys. It is also used for production of lithium hydride and lithium nitride. 

Aromatic polysulfites can be produced if bisphenols, eg, bisphenol A, are heated with diphenyl sulfite in the presence of lithium hydride (112). Halosulfates and Halosulfites. A general method for the preparation of alkyl halosulfates and halosulfites is the treatment of the alcohol with sulfuryl or thionyl chloride at low temperatures while passing an inert gas through the mixture to remove hydrogen chloride (113). 

In a similar manner, 47/-[l,2,5]oxadiazolo[3,4- /]pyrimidine-5,7-dione 1-oxides 344 are conveniently prepared in high yields by the oxidative intramolecular cyclization of 6-amino-5-nitro-l/7-pyrimidine-2,4-diones 343 employing iodosylbenzene diacetate as an oxidant in the presence of lithium hydride (Equation 80) <1998JOG6947>. 

It is prepared by the gradual addition of aluminium chloride to a slurry of lithium hydride in ether. The precipitated LiCl and unreacted LiH are fdtered off. 

Aluminum hydride is prepared by the reaction of lithium hydride with aluminum chloride in diethyl ether... 

To a solution of lithium diisopropylamide. prepared from 5.04 mL (35.6 mmol) of diisopropylamine, 22.3 mL (35.6 mmol) of a 1.6 M solution of butyllithium in hexane and 34 mL of THF at —78 C is added dropwise a solution of 5.44 g (32.4 mmol) of ( + )-l-[(R)-ethylsulfinyl]-4-methylbcnzene sulfoxide in 37 mL of THF. A suspension of lithium bromoacetate, prepared from 6.75 mL (48.6 mmol) of bromoacetic acid and 5.15 g (64.84 mmol) of lithium hydride in 50 mL of THF, is added at the same temperature to the yellow solution of the sulfinyl anion. The mixture is stirred for 5 min at — 78 °C, sat. aq NH4C1 is added, and then 10 M hydrochloric acid is added dropwise until the solution reaches pH 2. The mixture is extracted with ethyl acetate, the extracts are concentrated, chromatography of the residue gives the product yield 4.24 g (58%) mp 53-55rC (hexane/diethyl ether). 

The alcoholysis of sulfites such as dimethyl sulfite offers a convenient method for the preparation of high-boiling dialkyl sulfites [33]. Earlier, Voos and Blanke [8a] reported that dimethyl sulfite is converted to diethyl sulfite in 44 % yield. The reaction was shown to be acid-catalyzed and failed when barium carbonate was present. However, a patent refers to the use of lithium hydride in the transalcoholysis of 2,2-(4,4 -dihydroxyphenyl)propane with diphenyl sulfite or di-o-cresyl sulfite [32]. Recently Mehrotra and Mathur [34] reported that the alcoholysis reaction proceeds in the absence of catalysts. Their results are summarized in Eqs. (21)—(23) and Table VII. Tertiary butanol did not... 

A synthesis of lapachol using reaction conditions better than those used by Fieser was carried out by Fridman et al [149].They used the lithium salt of 2-hydroxy-1,4-naphthoquinone prepared in situ instead of the silver salt used for Fieser [150]. The lithium salt was prepared in situ by addition of lithium hydride to the frozen solution of the quinone in dimethyl sulfoxide, Fig. (14). As the solution thawed, the lithium quinone was slowly formed and was then alkylated with 3,3-dimethylallyl bromide. Lapachol was thus obtained in 40% yield. 

Lithium tetrahydridogallate, which was first prepared by Finholt, Bond, and Schlesinger,1 is a very useful starting material for the preparation of gallium hydride derivatives.2-3 The present synthesis is based on an adaptation of the original preparation.1-4 Since gallium-hydrogen bonds are susceptible to hydrolysis, it is necessary to perform the preparation in the absence of air. The procedure described is based on the use of Schlenk-type inert-atmosphere techniques. 

If di(/butylainino)silane, a colorless liquid (bp 50 °C/3 mbar) easily prepared in tetrahydrofuran from commercially available dichlorosilane and rbutylamine in a molar ratio of 1 4, is freated at 0 °C with an equimolar amount of nbutyl lithium in npentane, lithiation of one N-H group as well as cyclization combined with elimination of hydrogen occurs (Eq. 2). Reactions of this type are known from the literature [4, 5] to proceed at higher temperature or in the presence of small amounts of an alkali metal or its hydride. We therefore assume that traces of lithium hydride formed in a side reaction might have catalyzed the formation of compound 4a. 

The reagent is prepared in THF solution by the reaction of lithium hydride (2, 251) with triethylborane. It is stable indefinitely. 

Lithium hydride is an industrial product utilized in organic synthesis, preparation of other hydrides, etc. The hydride, deuteride and tritide of Li play a role in the nuclear industry. 

Direct displacement of chloride in acyl chlorides by hydride has been used to prepare aldehydes in 25-50% yield through the use of lithium hydride. " It was necessary to reflux the acid chloride in benzene or toluene with freshly prepared lithium hydride for 4-20 h. Under these conditions, there is the distinct likelihood that, when formed, aldehydes with a-hydrogen atoms would undergo aldol condensation. Sodium and calcium hydrides afforded only traces of aldehyde. 

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