Alkali metals reactions with alcohols

In all cases, dithio-phosphorus acids can be liberated from their alkali-metal salts by reacting them with acids such as HC1. Thio-ester derivatives of the dithio-phosphorus acids can be synthesised via reaction of the acids themselves with an alcohol or phenol (Equation 26) or from reaction of their alkali-metal salt with an alkyl halide (Equation 27). 

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. 

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequently used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkali catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonitrile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkali metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Giignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

OXALIC ACID (144-62-7) CjHjO. HOOCCOOH Combustible solid heat-sensitive. (combustible <215 F/101°C. Fire Rating 1). Exposure to elevated temperatures, hot surfaces, or flames causes decomposition and the formation of toxic and flammable formic acid and carbon monoxide. Hygroscopic the solution in water is a medium-strong acid. Violent reaction with strong oxidizers, acid chlorides alkali metals bromine, furfuryl alcohol hydrogen peroxide (90%) phosphorus trichloride silver powders sodium, sodium chlorite sodium hypochlorite urea + heat (forms NHj gas, CO2 and CO may explode). Mixture with some silver compounds forms explosive salts of silver oxalate. Incompatible with caustics, mercury, urea. On small fires, use dry chemical powder (such as Purple-K-... 

THIOBUTYL ALCOHOL (109-79-5) Forms explosive mixture with air (flash point 35°F/2°C). May react with water, steam, or acids to produce toxic and flammable vapors. Violent reaction, ignition, or explosion with strong oxidizers, calcium hypochlorite, strong acids, alkalis, alkali metals. Incompatible with aliphatic amines, ethylene oxide, isocyanates, nitric acid, sulfuric acid. Attacks some forms of plastics, coatings, and rubber. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

By reactions with alcohols and phenols in the presence of base 15 J.2.2.3 By reactions with alkali metal alkoxides and phenoxides... 

Most metal chlorides undergo only partial metathetical halide/alkoxide exchange upon reaction with alcohols or no reaction at all even at elevated temperatures. The metal alkoxide chlorides thus obtained, MClx(OR), have not been used in sol-gel processing (see, however. Section 7.10.3.3.2). In order to achieve the preparation of homoleptic metal alkoxides from metal chlorides basic conditions are essential in order to trap the liberated HCl. This can be achieved by reaction of metal chlorides with alcohols in the presence of a base such as ammonia or, less often, trialkylamines or pyridine (Equation (11a)). The base also increases the equilibrium concentration of alkoxide ions, which are a more powerful nucleophile for reaction with the metal chloride than the parent alcohol. For this reason the use of alkali alkoxides (M OR), mostly lithium, sodium, or potassium alkoxides, proves to be more successful (Equation (11b)). The use of LiOR has advantages for the preparation of insoluble metal methoxides because LiCl is soluble in methanol and is thus easily separated from insoluble metal alkoxides. 

The alkali metals and their alcoholates react with water, fatty acids and peroxides. The quantities of catalyst which are inactivated by these substances are given in Table 5.5. The figures show the importance of using a dry and well-refined oil as the starting material for the reaction. With such an oil the quantity of catalyst used for the reaction is of the order of 0.1-0.2% alkali metal or 0.2-0.3% of methylate. 

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