With alcohols

C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

CO. Alkynes will react with carbon monoxide in the presence of a metal carbonyl (e.g. Ni(CO)4) and water to give prop>enoic acids (R-CH = CH-C02H), with alcohols (R OH) to give propenoic esters, RCH CHC02R and with amines (R NH2) to give propenoic amides RCHrCHCONHR. Using alternative catalysts, e.g. Fe(CO)5, alkynes and carbon monoxide will produce cyclopentadienones or hydroquinols. A commercially important variation of this reaction is hydroformyiation (the 0x0 reaction ). 

Crude chlorophyll is prepared commercially from alfalfa meal or nettles by extraction with alcohol and partition into benzene. It is used as a colouring matter, particularly for foods and pharmaceutical products. 

Alternatively, the azide may be boiled with alcohol to convert it into the urethane, and the... 

Ethylamine, monoethylamine, CH3CH2NH2-B.p. 19 C. Prepared by reduction of acetonitrile or by heating ethyl chloride with alcoholic ammonia under pressure. It is a strong base and will displace ammonia from ammonium salts. Forms a crystalline hydrochloride and also crystalline compounds with various metallic chlorides. 

They are colourless liquids with characteristic odours, and are prepared by the condensation of ketones with alkyl orthoformates in the presence of alcohols, or by the reaction of acetylenes with alcohols in presence of HgO and BF3. In some cases trichloroethanoic acid is used as the catalyst. They lose alcohol when heated and form vinyl ethers. Exchange of alcohol groups occurs when the ketals of the lower alcohols are boiled with alcohols of greater molecular weight. See acetals. 

Cj jH,2N202. Used as its sodium salt, which is a white hygroscopic powder. Unstable, readily absorbing carbon dioxide and liberating phenytoin. Made by treating a-bromodi-phenylacetylurea with alcoholic ammonia. It has a mild hypnotic and strong anticonvulsant action, and is used in the treatment of grand-mal and focal epilepsy. 

Prepared by epoxidation of styrene with per-oxyelhanoic acid. Reactions are similar to those of aliphatic epoxides (s e, e.g. ethylene oxide). Reacts with alcohols to give mono-ethers, e g. PhCH(0Me)CH20H. Phenols give resins. 

In both cases, the precipitate must be filtered and dried quickly, by washing first with alcohol and then with ether (to prevent formation of the copper(II) compound). 

The reaction between 3,5 dinitrobenzoyl chloride and compounds containing the OH, NHj, or NH groups is very rapid, and therefore is particularly suitable for identification purposes cf. pp. 335, 338, 381). It is usual to have sodium hydroxide present during the reaction with phenols and amino-acids, but this is not necessary with alcohols if they are dry. 

Although benzenesulphonyl chloride has for simplicity been used in the above discussion, tolucne-/>- sulphonyl chloride, CHaCeH SO Cl, is more frequently used in the laboratory, owing to its much lower cost, the latter being due in turn to the fact that toluene-p-sulphonyl chloride is a by-product in the commercial preparation of saccharin. Toluene-p sulphonyl chloride is a crystalline substance, of m.p. 68° the finely powdered chloride will, however, usually react readily with amines in the Schotten-Baumann reaction it does not react so readily with alcohols, but the reaction may be promoted considerably by first dissolving the chloride in some inert water-soluble solvent such as acetone. 

Aliphatic halides, and aromatic hydrocarbons with halogen in side-chain, are readily hydrolysed by boiling with alcoholic NaOH solution. 

Hydrolysis with alcoholic NaOH solution. Boil together in a small conical flask, fitted with a reflux water-condenser, 1 ml. of chloroform and 10 ml. of alcoholic NaOH solution for 10 minutes. Then dilute with water to dissolve any NaCl which may have separated, add dil. HNO3 until acid and then AgN03 solution. A copious precipitate of AgCl is produced. 

Methyl iodide, ethyl bromide and ethyl iodide also evolve small amounts of ethylene when treated as above. If this is suspected, a small quantity of the substance should be heated with alcoholic NaOH solution in a small flask, fitted with a knee delivery-tube. Pass the gas evolved through a very dilute solution of KMn04 which has been made alkaline with aqueous NagCOj solution. If ethylene has been formed, a brown precipitate of MnOj will be produced (a transient green colour may appear). 

I he methyl iodide is transferred quantitatively (by means of a stream of a carrier gas such as carbon dioxide) to an absorption vessel where it either reacts with alcoholic silver nitrate solution and is finally estimated gravimetrically as Agl, or it is absorbed in an acetic acid solution containing bromine. In the latter case, iodine monobromide is first formed, further oxidation yielding iodic acid, which on subsequent treatment with acid KI solution liberates iodine which is finally estimated with thiosulphate (c/. p. 501). The advantage of this latter method is that six times the original quantity of iodine is finally liberated. 

It forms excellent freezing mixtures with many organic liquids, e.g., with alcohol, — 72° with ether, — 77° and with chloroform, — 77°. 

---