Nitrogen reaction with lithium

The most rambvmctious member of the family from the standpoint of rapid growth into many markets is lithium. Here we have what is really a half-brother of sodium and potassiiun, since lithiiun resembles the alkaline earth metals in so many ways—in its relatively covalent nature, its reaction with nitrogen, the relative insolubihty of its salts in water, and their relative solubility in organic solvents. Lithium metal applications of interest today include those in polymerization catalysis and in organic synthesis as well as in classified fields pertaining to futuristic fuels. 

Lithium reacts with nitrogen gas according to the reaction ... 

After the air in the flask had been completely replaced with nitrogen, it was cooled in a liquid nitrogen bath and a solution of 25 g of acetylene in 160 ml of dry THF was introduced. The solution had been prepared by dissolving acetylene (freed from acetone by means of a cold trap) in THF cooled at -80 to -90°C. A solution of 0.21 mol of butyl lithium in about 150 ml of hexane was added in 5 min to the vigorously stirred solution. During this addition the temperature of the mixture was kept between -80 and -100°C by occasionally dipping the flask into the liquid nitrogen. To the white suspension were successively added at -80°C a solution of 10 g. of anhydrous lithium bromide (note 1) in 30 ml of THF and 0.20 mol of freshly distilled benzaldehyde. The reaction mixture was kept for 3 h at -69°C, after which the temperature was allowed to rise to +10°C over a period of 2 h. 

Normally, lithium hydride ignites in air only at high temperatures. When heated it reacts vigorously with CO2 and nitrogen. With the former, lithium formate is obtained. Reaction at high temperature with nitrogen produces lithium nitride. Therefore, dry limestone or NaCl powders are used to extinguish LiH fires. Lithium hydride reacts exothermically with moist air and violently with water. 

The determination of position of protonation by reaction with diazomethane was performed as follows The enamine was treated at —70° with ethereal hydrogen chloride and the suspension of precipitated salt was treated with diazomethane and allowed to warm slowly to —40°, at which temperature nitrogen was liberated. The reaction with lithium aluminum hydride (LAH) was carried out similarly except that an ether solution of LAH was added in place of diazomethane. The results from reaction of diazomethane and LAH 16) are summarized in Table 1. 

Since the nitrogen in pyridine is electron attracting it seemed reasonable to predict that the trihalopyridynes would also show the increased electrophilic character necessary to form adducts with aromatic hydrocarbons under similar conditions to those employed with the tetra-halogeno-benzynes. The availability of pentachloropyridine suggested to us and others that the reaction with w-butyl-lithium should lead to the formation of tetrachloro-4-pyridyl-lithium 82 84>. This has been achieved and adducts obtained, although this system is complicated by the ease with which pentachloropyridine undergoes nucleophilic substitution by tetrachloro-4-pyridyl lithium. Adducts of the type (45) have been isolated in modest yield both in the trichloro- and tribromo- 58) series. 

These compounds are thermally stable, but sensitive to oxidation. The boron atom is not very reactive, due to conjugation of its vacant orbital with the nitrogen lone electron pair, resulting in the absence of intermolec-ular coordination. However, these compounds undergo reactions with methanol, giving methoxy derivatives (172). The latter interact with lithium alkylides, and form, depending on their nature, borates (173) or 13-alkyl derivatives (174) [Eq. (131)]. 

Precursors for this task were obtained by addition of /-butylmagnesium bromide to the central bond of [1.1.1 ]propellane 40a followed by conversion of the 3-f-butylbicyclo[ 1.1.1 Jpentyl-1 -y 1-magnesium bromide (88) into the ketones 89 by standard methods.27 Reaction of ketones 89 with tosyl hydrazide afforded the hydrazones 90, which gave the corresponding lithium salts 91 by reaction with MeLi in ether. These salts were dried under high vacuum and then pyrolized at 4 x 10 5 torr in the temperature range of 100-130°C and the volatile products condensed in a liquid nitrogen-cooled trap. 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladimn chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, - by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazone with sodium hydride. ... 

It is electropositive and thus an excellent reducing agent because it readily gives up electrons in chemical reactions. Lithium is the only metal that reacts with nitrogen at room temperature. When a small piece of the metal, which is usually stored in oil or kerosene, is cut, the new surface has a bright, shiny, silvery surface that soon turns gray from oxidation. 

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