Alcohols hydration

The equilibrium constants Ka, K, and h2o are conveniently summarized in Scheme 10 in the form of a cycle similar to that shown above for the a-phenethyl and t-butyl cations (Schemes 1 and 4). It is worth noting that P h2o measures the stability of the double bond relative to the alcohol (hydrate). If p fR was converted to HIA, p h2o in the cycle would be replaced by the energy of hydrogenation. The latter provides the conventional measure of double bond stability, save that here free energy in aqueous solution is measured rather than the more usual heat of hydrogenation in the gas phase. 

Examples Acid salts, acids, proton sponges, HF complexes Acids, alcohols, hydrates, phenols, biological molecules Weak base, basic salts C-H- O/N O/N-H- ji... 

With water-alcohol, both molecules with an OH dipole, the cause of the positive heat of mixing is to be found elsewhere. In view of the strong volume contraction, which occurs on mixing, the packing in water-alcohol mixtures is appreciably denser than in water and alcohol themselves. In particular water has an open, partly ordered structure (p. 380). The introduction of alcohol molecules disturbs this structure and the dense packing itself gives rise to a low energy content the formation of definite alcohol hydrates does not occur here. 

The Beckmann rearrangement of ketoximes to the corresponding amides (31), the Fischer indole cyclization, isomerization of epoxides to the corresponding aldehydes, ketones, or alcohols, hydration and ammo-nolysis of epoxides, oxygen-sulfur interchange, formation of diaryl-ureas and -thioureas from condensation of aniline and carbonyl sulfide, and olefin carbonylation occur over zeolite catalysts (62). The oxo reaction over rhodium and cobalt containing zeolites recently has been claimed (22). 

The commerce in. and use of. alcohol in the United States is. strictly controlled by the Treasury Department, which has provided the following definition for "alcohol" "The term alcohol means that substance known as ethyl alcohol, hydrated oxide of ethyl, or spirit of wine, front whatever source or whatever process produced, having a proof of 160 or more and not including the substances commonly known as whiskey, brandy, rum. or gin."... 

Further, following up on Jeffrey s early work on amine hydrates (amine semiclathrates), numerous amines remain to be explored for hydrate phases. In particular, since it has also been observed that some amine clathrates as weU as stoichiometric alcohol hydrates show phase transitions to double clathrate hydrates in the presence of helpgases such as xenon, H2S, and methane, it becomes a worthwhile area for exploration. 

Hexahoi Hexene Hexone Hexyl Alcohol Hydrated Lime... 

The hydration of olefins has long been practiced for the manufacture of amyl and isopropyl alcohol, and more recently for ethyl alcohol. Hydration is usually accomplished by a series of reactions involving the chlorides or alkyl sulfates, rather than the direct hydration reaction indicated here. 

Figure 10.3a shows a simplified fiowsheet for the production of isopropyl alcohol by the direct hydration of propylene. Different reactor technologies are available for the process, and separation and recycle systems vary, but Fig. 10.3a is representative. Propylene... 

Figure 10.3 Outline flowsheet for the production of isopropyl alcohol by direct hydration of propylene. (From Smith and Petela, Chem. Eng., 513 24, 1991 reproduced by permission of the Institution of Chemical Engineers.)...

Borneol and isoboineol are respectively the endo and exo forms of the alcohol. Borneol can be prepared by reduction of camphor inactive borneol is also obtained by the acid hydration of pinene or camphene. Borneol has a smell like camphor. The m.p. of the optically active forms is 208-5 C but the racemic form has m.p. 210-5 C. Oxidized to camphor, dehydrated to camphene. 

CCls CHO. A colourless oily liquid with a pungent odour b.p. 98°C. Manut actured by the action of chlorine on ethanol it is also made by the chlorination of ethanal. When allowed to stand, it changes slowly to a white solid. Addition compounds are formed with water see chloral hydrate), ammonia, sodium hydrogen sulphite, alcohols, and some amines and amides. Oxidized by nitric acid to tri-chloroethanoic acid. Decomposed by alkalis to chloroform and a methanoate a convenient method of obtaining pure CHCI3. It is used for the manufacture of DDT. It is also used as a hypnotic. 

Van Oss and Good [148] have compared solubilities and interfacial tensions for a series of alcohols and their corresponding hydrocarbons to determine the free energy of hydration of the hydroxyl group they find -14 kJ/mol per —OH group. 

Isocyanide reaction. Since chloral hydrate is readily converted into chloroform by alkali, it will give the isocyanide reaction. To a few crystals of the solid add about 5 ml. of alcoholic NaOH solution and a few drops of aniline, and heat the disagreeable odour of phenyl isocyanide, C H(NC, is rapidly detected. 

Note. PRIMARY ALIPHATIC AMINES. The lower amines are gases or low-boiling liquids (b.ps. CHjNH, 7 CiHjNH, 17 CH,(CH2,>,NH 49 (CHg)jCHNHa, 34 ) but may be encountered in aqueous or alcoholic solution, or as their crystalline salts. They are best identified as their benzoyl, or toluene-/>-sulphonyl derivatives (c/. (C) above), and as their picrates when these are not too soluble. This applies also to benzylamine, CjHsCHjNH, b.p. 185 also to ethylenediamine, usually encountered as the hydrate, NHj (CHj)j NH2,HjO, b.p. 116 , for which a moderate excess of the reagent should be used to obtain the di-acyl derivative. (M.ps., pp. 55 55 )... 

Monohydric alcohols, aldehydes (including chloral hydrate), ketones, cinnamic acid, amines (2-naphthylaminc is odourless), nitrophenols (resemble both phenol and nitro-compound),... 

The reagent must be carefully protected from moisture as it is comparatively easily hydrated to the acid, m.p. 216-218° (sealed capillary tube). Dilute aqueous solutions of an alcohol should be treated with solid potassium carbonate and the alcohol layer used for the test. 

Place 1 0 ml. of hydrazine hydrate (CAUTION corrosive chemical) in a test-tube fitted with a short refiux condenser. Add 10 g. of the methyl or ethyl ester dropwise (or portionwise) and heat the mixture gently under refiux for 15 minutes. Then add just enough absolute ethanol through the condenser to produce a clear solution, refiux for a further 2-3 hours, distil oflF the ethyl alcohol, and cool. Filter oflF the crystals of the acid hydrazide, and recrystallise from ethanol, dilute ethanol or from water. 

Fit a 1500 ml. bolt-head flask with a reflux condenser and a thermometer. Place a solution of 125 g. of chloral hydrate in 225 ml. of warm water (50-60°) in the flask, add successively 77 g. of precipitated calcium carbonate, 1 ml. of amyl alcohol (to decrease the amount of frothing), and a solution of 5 g. of commercial sodium cyanide in 12 ml. of water. An exothermic reaction occurs. Heat the warm reaction mixture with a small flame so that it reaches 75° in about 10 minutes and then remove the flame. The temperature will continue to rise to 80-85° during 5-10 minutes and then falls at this point heat the mixture to boiling and reflux for 20 minutes. Cool the mixture in ice to 0-5°, acidify with 107-5 ml. of concentrated hydrochloric acid. Extract the acid with five 50 ml. portions of ether. Dry the combined ethereal extracts with 10 g. of anhydrous sodium or magnesium sulphate, remove the ether on a water bath, and distil the residue under reduced pressure using a Claiseii flask with fractionating side arm. Collect the dichloroacetic acid at 105-107°/26 mm. The yield is 85 g. 

The modified procedure involves refluxing the N-substituted phthaUmide in alcohol with an equivalent quantity of hydrazine hydrate, followed by removal of the alcohol and heating the residue with hydrochloric acid on a steam bath the phthalyl hydtazide produced is filtered off, leaving the amine hydrochloride in solution. The Gabriel synthesis has been employed in the preparation of a wide variety of amino compounds, including aliphatic amines and amino acids it provides an unequivocal synthesis of a pure primary amine. 

Benzylatnine. Warm an alcoholic suspension of 118-5 g. of finely-powdered benzyl phthalimide with 25 g. of 100 per cent, hydrazine hydrate (CAUTION corrosive liquid) a white, gelatinous precipitate is produced rapidly. Decompose the latter (when its formation appears complete) by heating with excess of hydrochloric acid on a steam bath. Collect the phthalyl hydrazide which separates by suction filtration, and wash it with a little water. Concentrate the filtrate by distillation to remove alcohol, cool, filter from the small amount of precipitated phthalyl hydrazide, render alkaline with excess of sodium hydroxide solution, and extract the liberated benzylamine with ether. Dry the ethereal solution with potassium hydroxide pellets, remove the solvent (compare Fig. //, 13, 4) on a water bath and finally distil the residue. Collect the benzylamine at 185-187° the 3ueld is 50 g. 

Excellent results may be obtained by conducting the acetylation in aqueous solution (cf. Section IV,45). Dissolve 0-5 g. of the amine in 2N hydrochloric acid, and add a little crushed ice. Introduce a solution of 5 g. of hydrated sodium acetate in 25 ml. of water, followed by 5 ml. of acetic anhydride. Shake the mixture in the cold until the smell of acetic anhydride disappears. Collect the solid acetyl derivative, and recrystallise it from water or dilute alcohol. 

Method 2. Drop 10 g. of hydrazine hydrate (85 per cent, aqueous solution see Section 11,49,Id) into a hot solution of 35 g. of benzil (Section IV,126) in 70 ml. of alcohol with stirring. When about three-fourths of the hydrazine hydrate has been introduced, the product begins to separate. After all the reagent has been added, heat the solution under reflux for 5 minutes, cool to 0°, filter at the pump, and wash twice with 20 ml. portions of alcohol. The yield of benzil monohydrazone, m.p. 149-151° (decomp.), is almost quantitative. 

Girard s reagent P , C5H5NCH2C0NHNH2 C1. In a 1-htre threenecked flask, equipped as in the previous preparation, place 200 ml. of absolute ethyl alcohol, 63 g. (64 -5 ml.) of pure anhydrous pyridine and 98 - 5 g. (84 5 ml.) of ethyl chloroacetate. Heat the mixture under reflux for 2-3 hours until the formation of the quaternary salt is complete acidify a small test-portion with dilute sulphuric acid it should dissolve completely and no odour of ethyl chloroacetate should be apparent. Cool the mixture in ice and salt. Replace the thermometer by a dropping funnel, and add a solution of 40 g. of 100 per cent, hydrazine hydrate in 60 ml. of absolute ethanol all at once. A vigorous exothermic reaction soon develops and is accompanied by vigorous effervescence. The pro duct separates almost immediately. When cold, filter with suction, wash... 

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