Alcohol, Absolute

Drying by hydrolysis. The production of extremely dry (99 -9-(- per cent.) ethyl alcohol from commercial absolute alcohol (99-f percent.) is possible by taking advantage of the fact that the hydrolysis of an ester consumes water. Thus if the absolute alcohol is treated with a little sodium in the presence of an ester of high boiling point e.g., ethyl... 

Absolute ethyl alcohol. Ethyl alcohol of a high degree of purity is frequently required in preparative organic chemistry. For some purposes alcohol of ca. 99 -5 per cent, purity is satisfactory this grade may be purchased (the absolute alcohol of commerce), or it may be conveniently prepared by the dehydration of rectified spirit with quicklime. Rectified spirit is the constant boiling point mixture which ethyl alcohol forms with water, and usually contains 95 6 per cent, of alcohol by weight. Wherever the term rectified spirit is used in this book, approximately 95 per cent, ethyl alcohol is to be understood. 

Extremely dry (or super-dry ) ethyl alcohol. The yields in several organic preparations e.g., malonic ester syntheses, reduction with sodium and ethyl alcohol, veronal synthesis) are considerably improved by the use of alcohol of 99-8 per cent, purity or higher. This very high grade ethyl alcohol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with quicklime (see under 4). 

If preferred, the following alternative procedure may be adopted. The absolute alcohol is placed in a 1 5 or 2 litre three-necked flask equipped with a double surface reflux condenser and a mercury-sealed mechanical stirrqr the third neck is closed with a dry stopper. The sodium is introduced and, when it has reacted completely, the ester is added and the mixture is gently refluxed for 2 hours. The reflux condenser is then rapidly disconnected and arranged for downward distillation with the aid of a short still head or knee tube. The other experimental details are as above except that the mixture is stirred during the distillation bumping is thus reduced to a minimum. 

One litre of commercial absolute alcohol (or any ethyl alcohol of 99 per cent, purity or better) is treated with 14 g. of clean, dry sodium when the sodium has completely reacted, 40 g. of pure ethyl formate are added. The mixture is refluxed for 2-3 hom , and the dry alcohol is distilled oflF as in Method 2 the first 25 ml. of distillate are discarded. The super-dry alcohol contains about 0 03 per cent, of water. 

Reduction of ketones either with sodium and absolute alcohol, example ... 

Absolute alcohol is not essential for this reduction 70-76 per cent, alcohol gives satisfactory results... 

The alcoholic sliver nitrate solution consists of a saturated solution of silver nitrate in absolute alcohol (about 1-2 per cent.). 

Mix 50 ml. of formalin, containing about 37 per cent, of formaldehyde, with 40 ml. of concentrated ammonia solution (sp. gr. 0- 88) in a 200 ml. round-bottomed flask. Insert a two-holed cork or rubber stopper carrying a capillary tube drawn out at the lower end (as for vacuum distillation) and reaching almost to the bottom of the flask, and also a short outlet tube connected through a filter flask to a water pump. Evaporate the contents of the flask as far as possible on a water bath under reduced pressure. Add a further 40 ml. of concentrated ammonia solution and repeat the evaporation. Attach a reflux condenser to the flask, add sufficient absolute ethyl alcohol (about 100 ml.) in small portions to dissolve most of the residue, heat under reflux for a few minutes and filter the hot alcoholic extract, preferably through a hot water fuimel (all flames in the vicinity must be extinguished). When cold, filter the hexamine, wash it with a little absolute alcohol, and dry in the air. The yield is 10 g. Treat the filtrate with an equal volume of dry ether and cool in ice. A fiulher 2 g. of hexamine is obtained. 

Dissolve 1 g. of the ketomethylene compound and 1 1 g. or 2 2 g. of pure benzaldehyde (according as to whether the compound may be regarded as RCOCHjR or as RCHjCOCHjR ) in about 10 ml. of rectified (or methylated) spirit, add 0 5 ml. of 5.N -sodium hydroxide solution, shake and allow the mixture to stand for about an hour at room temperature. The benzylidene derivative usually crystallises out or will do so upon scratching the walls of the vessel with a glass rod. Filter off the solid, wash it with a little cold alcohol, and recrystallise it from absolute alcohol (or absolute industrial spirit). 

From the silver salt. By refluxing the dry silver salt with an alkyl halide in anhydrous ether, benzene or absolute alcohol solution, for example ... 

Use 01 g. of the platinum oxide catalyst and 11 4 g, of pure cinnamic acid dissolved in 100 ml. of absolute alcohol. The theoretical volume of hydrogen is absorbed after 7-8 hours. Filter off the platinum, and evaporate the filtrate on a water bath. The resulting oil solidifies on cooling to a colourless acid, m.p. 47-48° (11-2 g.). Upon recrystallisation from light petroleum, b.p. 60-80°, pure dihydrocinnamic acid, m.p. 48-49°, is obtained. 

Cool the mixture and decant the solution from the sodium bromide wash the salt with two 20 ml. portions of absolute alcohol and add the washings to the main solution. Distil off the alcohol, which contains the slight excess of n-propyl bromide used in the condensation, through a short fractionating column from a water bath. The residue A) of crude ethyl n-propylacetoacetate may be used directly in the preparation of methyl n-butyl ketone. If the fairly pure ester is required, distil the crude product under diminished pressure and collect the fraction boihng at 109-113727 mm. (183 g.) (R). 

If the absolute alcohol of commerce is used, the yield is appreciably diminished. 

The high sodium ion concentration results in facile crystallisation of the sodium salt. This process of salting out with common salt may be used for recrystallisation, but sodium benzenesulphonate (and salts of other acids of comparable molecular weight) is so very soluble in water that the solution must be almost saturated with sodium chloride and consequently the product is likely to be contaminated with it. In such a case a pure product may be obtained by crystallisation from, or Soxhlet extraction with, absolute alcohol the sul-phonate is slightly soluble but the inorganic salts are almost insoluble. Very small amounts of sulphones are formed as by-products, but since these are insoluble in water, they separate when the reaction mixture is poured into water ... 

To prepare the solid phenyldlazonlum chloride or sulphate, the reaction is conducted in the absence of water as far as possible. Thus the source of nitrous acid is one of its organic esters (e.g., amyl nitrite) and a solution of hydrogen chloride gas in absolute alcohol upon the addition of ether only the diazonium salt is precipitated as a crystalline solid, for example ... 

Allow a mixture of 0-5 g. of the tertiary amine and 0-5 ml. of colourless methyl iodide to stand for 5 minutes. If reaction has not occurred, warm under reflux for 5 minutes on a water bath and then cool in ice water. The mixture will generally set solid if it does not, scratch the sides of the tube with a glass rod. RecrystaUise the solid product from absolute alcohol, ethyl acetate, acetone, glacial acetic acid or alcohol-ether. 

Place 10 ml. of pure benzaldehyde (Section IV,115) and 100 ml. of concentrated aininonia solution (sp. gr. 0-88) in a 250 ml. wide-mouthed reagent bottle. Cork the bottle securely, shake vigorously for 10 minutes and allow to stand with occasional shaking for 24 hours. By this time the benzaldehyde should be converted into a hard mass of hydrobenz-amide. Break up the solid mass with a spatula or a thick glass rod, filter with suction, wash with water, and drain thoroughly. RecrystalUse from absolute alcohol (or absolute methylated spirit). The yield of hydrobenzamide (colourless crystals), m.p. 101°, is 7 g. It is easily hydrolysed by cold dilute acids. 

When acetone is condensed with ethyl cyanoacetate in the presence of a solution of anhydrous ammonia in absolute alcohol at —5°, the ammonium salt of the dicyano-imlde (I) is precipitated. Upon dissolving this salt in water and adding excess of concentrated hydrochloric acid, the crystalline dicyano-imide (II) is obtained. Hydrolysis of the last-named with strong sulphuric acid affords p p dimethylglutaric acid (III). 

A modified Hahn condenser, a form of partial condenser, is illustrated in Fig. VI, 12, 1 it is best constructed of Pyrex glass. The dimensions given are only approximate and may be varied slightly. The inside clearance should be approximately 0-3 cm. a water jacket should be fitted over the central portion of the side arm by moans of rubber stoppers. Alternatively, the side arm may have a length of about 10 cm. and a condenser fitted to this in the usual manner. An approximately 1 cm. layer of absolute alcohol is placed in the inner condensing tube and the top of the tube is connected to a reflux condenser. The outside of the condenser below the side arm should be insulated with asbestos cloth or paper. The refluxing mixture boils the ethyl alcohol in the inner tube, most of the isopropyl alcohol is returned to the flask and the acetone distils over. 

Place 1 55 g. of clean sodium in a 250 ml. round-bottomed flask equipped with a reflux condenser. Add 40 ml. of absolute alcohol (or rectified spirit). If all the sodium has not disappeared after the vigorous reaction has subsided, warm the flask on a water bath until solution is complete. Cool the mixture and add 10 g. of p-acetylaminophenol. Introduce 15 g. (8 ml.) of ethyl iodide slowly through the condenser and reflux the mixture for 45-60 minutes. Pour 100 ml. of water through the condenser at such a rate that the crystalline product does not separate if crystals do separate, reflux the mixture until they dissolve. Then cool the flask in an ice bath collect the crude phenacetin with suction and wash with a little cold water. Dissolve the crude product in 80 ml. of rectified spirit if the solution is coloured, add 2 g. of decolourising carbon and filter. Treat the clear solution with 125 ml. of hot water and allow to cool. Collect the pure phenacetin at the pump and dry in the air. The yield is 9-5 g., m.p. 137°. 

In a 2 litre round-bottomed flask, fitted with a double surface reflux condenser, place 11-5 g. of clean sodium. Add 250 ml. of absolute alcohol in one portion if the reaction is unduly vigorous, immerse the flask momentarily in ice. When all the sodium has reacted, add 80 g. (76 ml.) of ethyl malonate (Section 111,153), followed by a solution of 30 g. of dry urea in 250 ml. of hot (ca. 70°) absolute alcohol. Shake the mixture well, fit a calcium chloride (or cotton wool) guard tube to the top... 

Phenylpropanolamine. - With catalyst prepared as previously described from 0.5g of palladium chloride and 3g of charcoal, it was possible to reduce two portions of 9.8g of isonitrosopropio-phenone (0.06 mol), dissolved in 150 cc. of absolute alcohol containing 7. Og of hydrogen chloride, to phenylpropanolamine in from 145 - 190 minutes with yields of the isolated chloride from 9.4g to 11. Og, or 84 to 98% of the theoretical. After recrystallization from absolute alcohol the salt melted at 191°. The free base was obtained by treating an aqueous solution of the hydrochloride with alkali on cooling, the liberated amino alcohol solidified and after recrystallization from water melted at 103°."... 

The first identified complexes of unsubstituted thiazole were described by Erlenmeyer and Schmid (461) they were obtained by dissolution in absolute alcohol of both thiazole and an anhydrous cobalt(II) salt (Table 1-62). Heating the a-CoCri 2Th complex in chloroform gives the 0 isomer, which on standirtg at room temperature reverses back to the a form. According to Hant2sch (462), these isomers correspond to a cis-trans isomerism. Several complexes of 2,2 -(183) and 4,4 -dithiazolyl (184) were also prepared and found similar to pyridyl analogs (185) (Table 1-63). Zn(II), Fe(II), Co(II), Ni(II) and Cu(II) chelates of 2.4-/>is(2-pyridyl)thiazole (186) and (2-pyridylamino)-4-(2-pyridy])thiazole (187) have been investigated. The formation constants for species MLr, and ML -" (L = 186 or 187) have been calculated from data obtained by potentiometric, spectrophotometric, and partition techniques. 

With arylthioamides except for some nitrothiobenzamides (101), yields are usually higher than those obtained above, due to the increased stability of these amides under acidic conditions (3), Rj = Ph, yield 70 to 82% (264, 285, 336, 483, 578, 641). In this case, cyclizations are carried out several hours to reflux, in absolute alcohol, in the presence of melted sodium acetate and few drops of piperidine. 

When thioamides such as thiobenzamide are used directly, neither dioxane nor magnesium carbonate is necessary. Instead absolute alcohol with fused sodium acetate in the presence of piperidine is used (457). 

Compounds other than a-halocarbonyls and thiourea can lead to 2-aminothiazoles. Thus 3-halogenoalkynes (120) condensed with thiourea in absolute alcohol give 2-aminothiazoles (Scheme 56a) (497), with Rj = Me, Et, n-Bu, H CPh, and HjCCgH tR-p R2 = H, Ph, CgH4R, and Q-naphthyl. Yields ranged from 20 to 80% (497). 

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