Alcohols alkali metals and

From Metals and Alcohol. Alkali metals, alkaline earth metals, and aluminum react with alcohols to give metal alkoxides (2,3,65) ... 

The most common catalysts in order of decreasing reactivity are haUdes of aluminum, boron, zinc, and kon (76). Alkali metals and thek alcoholates, amines, nitriles, and tetraalkylureas have been used (77—80). The largest commercial processes use a resin—catalyst system (81). Trichlorosilane refluxes in a bed of anion-exchange resin containing tertiary amino or quaternary ammonium groups. Contact time can be used to control disproportionation to dichlorosilane, monochlorosilane, or silane. 

No attempt should be made to purify perchlorates, except for ammonium, alkali metal and alkaline earth salts which, in water or aqueous alcoholic solutions are insensitive to heat or shock. Note that perchlorates react relatively slowly in aqueous organic solvents, but as the water is removed there is an increased possibility of an explosion. Perchlorates, often used in non-aqueous solvents, are explosive in the presence of even small amounts of organic compounds when heated. Hence stringent care should be taken when purifying perchlorates, and direct flame and infrared lamps should be avoided. Tetra-alkylammonium perchlorates should be dried below 50° under vacuum (and protection). Only very small amounts of such materials should be prepared, and stored, at any one time. 

The term Birch reduction was originally applied to the reduction of aromatic compounds by alkali metals and an alcohol in ammonia. In recent years many chemists have used the term to include all metal-ammonia reductions, whether an alcoholic proton source is present or not. The author prefers to use the term Birch reduction to designate any reduction carried out in ammonia with a metal and a proton donor as or more acidic than an alcohol, since Birch customarily used such a proton donor in his extensive pioneering work. The term metal-ammonia reduction is best reserved for reductions in which ammonia is the only proton donor present. This distinction in terminology emphasizes the importance of the acidity of the proton donor in the reduction process. 

The alkynylation of estrone methyl ether with the lithium, sodium and potassium derivatives of propargyl alcohol, 3-butyn-l-ol, and propargyl aldehyde diethyl acetal in pyridine and dioxane has been studied by Miller. Every combination of alkali metal and alkyne tried, but one, gives the 17a-alkylated products (65a), (65c) and (65d). The exception is alkynylation with the potassium derivative of propargyl aldehyde diethyl acetal in pyridine at room temperature, which produces a mixture of epimeric 17-(3, 3 -diethoxy-T-propynyl) derivatives. The rate of alkynylation of estrone methyl ether depends on the structure of the alkyne and proceeds in the order propar-gylaldehyde diethyl acetal > 3-butyn-l-ol > propargyl alcohol. The reactivity of the alkali metal salts is in the order potassium > sodium > lithium. 

I) Refluxing said benzyl ester with an aqueous alcoholic alkali metal hydroxide solution to saponify the benzyl ester group, neutralizing the saponification mixture by the addition of hydrochloric acid, extracting the neutralized mixture with chloroform, and separating the resulting (S,N-ditrityl-L-cysteinyl)-L-proline. 

Bipyridine is likewise reduced to 4,4 -bipiperidine by sodium and amyl alcohol and by catalytic hydrogenation. " 2,2 -Dimethyl-4,4 -bipyridine is reduced to 2,2 -dimethyl-4,4 -bipiperidine. Electrochemical reduction of 4,4 -bipyridine affords 4,4 -bipiperidine and some partly reduced 4,4 -bipyridines. Further work on the electroreduction of 4,4 -bipyridine has been reported. Reduction of 4,4 -bipyridine by tin and hydrochloric acid " or by controlled catalytic hydrogenation - gives l,2,3,4,5,6-hexahydro-4,4 -bipyridine. 4,4 -Bipyridine is reduced to its 1,4-dihydro derivative by bisdihydropyridyl metal complexes and to its radical anion by alkali metals and related processes. " " The ionization constant of the radical anion has been determined. ... 

Mercury Arsenites.—Mercurous Orthoarsenite, Hg3As03, may be obtained by treating a solution of mercurous nitrate with one of sodium orthoarsenite6 or with a solution of arsenious oxide in 50 per cent, alcohol 6 in the latter case the mercurous nitrate solution should be acidified with nitric acid and sufficient alcohol added to produce a slight turbidity. The precipitate is pale yellow, but rapidly turns brown on exposure to air. It is slightly soluble in water, being slowly decomposed with separation of mercury. It is also decomposed by hydroxides and carbonates of alkali metals and of barium, and by ammonia. It dissolves in acids, but when these are dilute, basic salts gradually separate. 

The method of Gaver147 for nonreducing carbohydrates (refluxing the carbohydrate in alcoholic alkali metal hydroxide solution without concomitant azeotropic distillation) might give results similar to those obtained by the Wolfrom method.8 -" However, the presence of water and hydroxide ion in the final reaction mixture would probably cause a. small fraction of the product to be the hydroxide adduct. 

H. M. Dawson and J. McCrae, D. P. Konowaloff, and W. Gaus also used soln. of various salts of the alkali metals, and of potassium, sodium, cupric, or barium hydroxide in place of water and also copper sulphate, copper chloride, zinc sulphate, and cadmium iodide while M. 8. Sherrill and D. E. Russ examined the effect of ammonium chromate. W. Herz and A. Kurzer examined the distribution of ammonia between water and a mixture of amyl alcohol and chloroform. Observations on the distribution of ammonia between water and chloroform were made by T. S. Moore and T. F. Winmill, G. A. Abbott and W. C. Bray, and J. M. Bell. J. H. Hildebrand gave for the molar fraction N X104 of ammonia at 1 atm. press., and 25°, dissolved by ethyl alcohol, 2300 methyl alcohol, 2730 and water, 3300. 

Reductive cyclization of y-ethynyl ketones to allylic alcohols. This reaction was first reported by Stork et al., who used an alkali metal and liquid ammonia.1 The main by-products, at least in cyclization to A-norsteroids, result from overreduction. This side reaction can be prevented by use of sodium naphthalenide in THF or DME.2... 

The hypophosphites are all soluble. Those of barium and calcium, which are the least soluble, dissolve in 2-5 to 3-5 and 6 to 7 parts of water respectively. Those of the alkali metals and ammonium dissolve also in alcohol. Solutions of hypophosphites of the alkali metals are fairly stable, especially in the absence of air, and the salts generally may be obtained in well-crystallised forms by evaporation. More concentrated solutions often decompose, especially if alkaline, with evolution of phosphine. The dry salts are also fairly stable in the cold, but when heated decompose giving phosphine and hydrogen and leaving the pyro- or meta-phosphate. 

The subsequent decay of the a-hydroxyalkyl radicals by a mutual termination reaction should yield a glycol, by combination, and an aldehyde, by disproportionation. Thus, there is an interesting difference between the reaction of individual alkali metal atoms with solid alcohols at low temperatures and the corresponding reaction between alkali metals and liquid alcohols at room temperature when the major products are molecular hydrogen and alkoxide ions. 

Acid—Base Chemistry. Acetic acid dissociates in water, pA a = 4.76 at 25°C. It is a mild acid which can be used for analysis of bases too weak to detect in water (26). It readily neutralizes the ordinary hydroxides of the alkali metals and the alkaline earths to form the corresponding acetates. When the crude material pyroligneous acid is neutralized with limestone or magnesia the commercial acetate of lime or acetate of magnesia is obtained (7). Acetic acid accepts protons only from the strongest acids such as nitric acid and sulfuric acid Other acids exhibit very powerfiil, superacid properties in acetic acid solutions and are thus usefiil catalysts for esterifications of olefins and alcohols (27). Nitrations conducted in acetic acid solvent are effected because of the formation of the nitronium ion, NOJ. Hexamethylenetetramine [100-97-0] maybe nitrated in acetic acid solvent to yield the explosive cyclotiimethylenetrinitramine [121 -82-4], also known as cyclonit or RDX. 

This method makes use of the production of a less soluble metal salt (MX) to drive the reaction to completion. One commonly encountered problem with this route is the low solubility of the starting lanthanide halides. Exposure to anhydrous NH3 gas helps dissolve lanthanide halides [22]. Eollowing the addition of alkali metal and the appropriate alcohols, the desired alkoxide complexes can be obtained. This reaction is thought to proceed with the formation of a triamide... 

NIOSH REL (Chromium(VI)) TWA 0.025 mg(Cr(VI))/mh CL 0.05/15M SAFETY PROFILE Confirmed human carcinogen. Poison by subcutaneous route. Mutation data reported. A powerful oxidizer. A powerful irritant of skin, eyes, and mucous membranes. Can cause a dermatitis, bronchoasthma, chrome holes, damage to the eyes. Dangerously reactive. Incompatible with acetic acid, acetic anhydride, tetrahydronaphthalene, acetone, alcohols, alkali metals, ammonia, arsenic, bromine penta fluoride, butyric acid, n,n-dimethylformamide, hydrogen sulfide, peroxyformic acid, phosphorus, potassium hexacyanoferrate, pyridine, selenium. 

Cyclic anhydrides of dibasic acids are cleaved by alcohols to monoacid esters. Similarly, the anhydride ring is opened by alkali-metal and halomagnesium alkoxides to give the corresponding salts of the acid esters. ... 

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