Ammonia lithium and

Lithium Amide. Lithium amide [7782-89-0], LiNH2, is produced from the reaction of anhydrous ammonia and lithium hydride. The compound can also be prepared by the removal of ammonia from solutions of lithium metal in the presence of catalysts (54). Lithium amide starts to decompose at 320°C and melts at 375°C. Decomposition of the amide above 400°C results first in lithium imide, Li2NH, and eventually in lithium nitride, Li N. Lithium amide is used in the production of antioxidants (qv) and antihistamines (see HiSTAMlNE AND HISTAMINE ANTAGONISTS). 

Heating metallic lithium in a stream of gaseous ammonia gives lithium amide [7782-89-0] LiNH2, which may also be prepared from Hquid ammonia and lithium in the presence of platinum black. Amides of the alkaH metals can be prepared by double-decomposition reactions in Hquid ammonia. For example... 

Results of the reduction of unsaturated alcohols depend on the respective positions of the hydroxyl and the double bond. Since the hydroxyl group is fairly resistant to hydrogenolysis by catalytic hydrogenation almost any catalyst working under mild conditions may be used for saturation of the double bond with conservation of the hydroxyl [608]. In addition, sodium in liquid ammonia and lithium in ethylamine reduced double bonds without affecting the hydroxyl in non-allylic alcohols [608]. 

The reactions with germyl iodides were carried out at — 78° with dimethyl ether as solvent. To obtain good yields, the dilithium telluride must be free of ammonia and lithium amides2. 

Lithium nitride reacts with water to form ammonia and lithium hydroxide, according to the following balanced chemical equation ... 

SAFETY PROFILE A powerful irritant to skin, eyes, and mucous membranes. Flammable when exposed to heat or flame. Ammonia is liberated and Uthium hydroxide is formed when this compound is exposed to moisture. Reacts violently with water or steam to produce toxic and flammable vapors. Vigorous reaction with oxidizing materials. Exothermic reaction with acid or acid fumes. When heated to decomposition it emits very toxic fumes of LiO, NH3, and NOx. Used in synthesis of drugs, vitamins, steroids, and other organics. See also LITHIUM COMPOUNDS, AMIDES, AMMONIA, and LITHIUM HYDROXIDE. 

Aqueous salt solutions such as saturated zinc chloride or calcium thiocyanate can dissolve limited amounts of cellulose. Two non- aqueous solvents are ammonium thiocyanate in ammonia and lithium chloride in N,N-dimethylacetamide. Cellulose solutions up to about 15% can be made with these solvents. Blends of cellulose and poly(vinyl alcohol) have been prepared in N,N-dimethylacetamide-lithium chloride, and exhibited good miscibility due to their mutual ability to form intra-intermolecular hydrogen bonds between hydroxyl groups [35]. Miscible blends of cellulose and poly(vinylpyrrolidone) have been prepared by dissolution in dimethyl sulfoxide-paraformaldehyde and blending with poly(vinylpyrrolidone) dissolved in dimethyl sulfoxide [36,37]. Cellulose has also been blended with poly(ethylene glycol) in dimethylsulfoxide and paraformaldehyde [38]. 

The corresponding requirements for the absorbent are low saturation pressure compared to the refrigerant and low thermal capacity. Currently, no known substance fulfills all above requirements. The absorbent/refiigerant pairs most frequently encountered in the absorption chillers are water/ammonia and lithium bromide aqueous solution/water. The thermal characteristics of the water/ammonia mixture are shown in Fig. 5.86. 

Aminoalkoxy pentaerythritols are obtained by reduction of the cyanoethoxy species obtained from the reaction between acrylonitrile, pentaerythritol, and lithium hydroxide in aqueous solution. Hydrogen in toluene over a mthenium catalyst in the presence of ammonia is used (34). The corresponding aminophenoxyalkyl derivatives of pentaerythritol and trimethyl olpropane can also be prepared (35). 

Ammonium and Lithium Fluoroborates. Ammonia reacts with fluoroboric acid to produce ammonium fluoroborate (53). An alternative method is the fusion of ammonium bifluoride and boric acid (54) ... 

Like the other alkah metals (45), lithium has appreciable solubiUty in Hquid ammonia. A saturated solution at —33.2° C contains 15.7 mol lithium in 1000 g of ammonia, and at 19°C has a density of 0.477, lower than that of any other known Hquid. Lithium reacts readily in Hquid ammonia to form... 

Lithium acetyhde also can be prepared directly in hquid ammonia from lithium metal or lithium amide and acetylene (134). In this form, the compound has been used in the preparation of -carotene and vitamin A (135), ethchlorvynol (136), and (7j--3-hexen-l-ol (leaf alcohol) (137). More recent synthetic processes involve preparing the lithium acetyhde in situ. Thus lithium diisopropylamide, prepared from //-butyUithium and the amine in THF at 0°C, is added to an acetylene-saturated solution of a ketosteroid to directly produce an ethynylated steroid (138). 

Absorption Refrigeration Systems Two main absorption systems are used in industrial application lithium bromide-water and ammonia-water. Lithium bromide-water systems are hmited to evaporation temperatures above freezing because water is used as the refrigerant, while the refrigerant in an ammonia-water system is ammonia and consequently it can be applied for the lower-temperature requirements. 

The ammonia-water absorption system was extensively used until the fifties when the LiBr-water combination became popular. Figure 11-103 shows a simplified ammonia-water absorption cycle. The refrigerant is ammonia, and the absorbent is dilute aqueous solution of ammonia. Ammonia-water systems differ from water-lithium bromide equipment to accommodate major differences Water (here absorbent) is also volatile, so the regeneration of weak water solution to strong water solution is a fractional distillation. Different refrigerant (ammonia) causes different, much higher pressures about 1100-2100 kPa absolute in condenser. 

A competing reaction in any Birch reduction is reaction of the alkali metal with the proton donor. The more acidic the proton donor, the more rapid IS the rate of this side reaction. Alcohols possess the optimum degree of acidity (pKa ca. 16-19) for use in Birch reductions and react sufficiently slowly with alkali metals in ammonia so that efficient reductions are possible with them. Eastham has studied the kinetics of reaction of ethanol with lithium and sodium in ammonia and found that the reaction is initially rapid, but it slows up markedly as the concentration of alkoxide ion in the mixture... 

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

Several reports have indicated that 17-acetoxy-20-ketopregnane derivatives are deacetoxylated readily by both calcium and lithium. The diacetate of 17a-pregna-l,3,5(10)-triene-3,17j5-diol-20-one (79) is reduced to pregna-l,3,5(10)-trien-3-ol-20-one (80) in 76% yield with calcium in ammonia, and... 

To a solution of 1.38 g of estradiol 3-methyl ether (mp 118-119°) in 110 ml of anhydrous ether is added 140 ml of liquid ammonia followed by 1.4 g (42 eq per mole) of lithium wire in small pieces, and 10 min later 16 ml of absolute alcohol is added dropwise over a 10- to 20-min period. Occasionally frothing occurs during the last part of this addition but is easily controlled by stopping the stirrer temporarily. After removing most of the ammonia and carefully adding cold water, the product is extracted with ether, washed with Claisen alkali, water and saturated salt solution, and dried over sodium... 

The reduction is effected exactly as in Procedure 8a but using 0.61 g (0.088 g-atom) of lithium. After the crude reaction product has been washed well on the filter with cold water, it is dissolved in ethyl acetate, the solution is filtered through the sintered glass funnel to remove iron compounds from the ammonia, and the filtrate is extracted with saturated salt solution. The organic layer is dried over sodium sulfate and the solvent is removed. The solid residue is crystallized from methanol (120 ml) using Darco. The mixture is cooled in an ice-bath, the solid is collected, rinsed with cold methanol, and then air-dried to give 12.9 g (85%), mp 129-132° reported for the tetrahydropyranyi ether of 3j5-hydroxypregn-5-en-20-one, mp 129-131°. 

There are ample precedents for reductions of double bonds in conjugated enones with lithium in deuterioammonia (see section V-C). Examples of the reduction of saturated ketones in deuterated media appear only as side reactions (over reductions) during the above mentioned conversions. For experimental details, therefore, one should consult the literature for the analogous reductions in protic medium (see also chapter 1). The use of deuterioammonia is essential for labeling purposes since by using liquid ammonia and methanol-OD the resulting alcohol contains no deuterium. For the preparation of deuterioammonia see section IX-D. 

The preparation of 17j -hydroxy-4a-methyl-5a-androstan-3-one (3) which cannot be obtained by direct alkylation or via formyl or oxalyl ketones was achieved by Schaub in 40% yield by the Stork " alkylation procedure. As discussed in the introduction this method proceeds by trapping the A -enolate (2), obtained from (1) and lithium in liquid ammonia, with methyl iodide. 

Weiss ° treated 16-dehydro- (6), 17a-acetoxy- (8), 17a-hydroxy- (9) and 17a-bromopregnan-20-one (11) with a solution of lithium, barium, calcium or sodium in liquid ammonia and reacted the intermediate enolate anion (7) with the appropriate alkyl halide. 

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