Hydrochloric acid hydrolysis

Reactivity Hydrolysis products Rate of hydrolysis Hydrochloric acid and hydroxyacetophenone Not readily hydrolyzed... 

Acid hydrolyses are usually carried out by refluxing in 6 N aqueous hydrochloric acid (constant boiling) or 5 to 10% solutions of HC1 in methanol (to promote solubility) for 4 to 30 hr, depending on the lipid in question. Most glycerophosphatides are hydrolyzed by acid to fatty acids, glycerophosphate, and the free base, just as with alkali. However, inositol phosphatides initially yield inositol phosphate and diglycerides on acid hydrolysis. Hydrochloric acid is easily removed by vacuum, which makes chromatographic examination of the hydrolysis products easier. 

Mustard gas is a liquid which boils at 216°, freezes at 14°, and slowly hydrolyzes when in contact with water. It is the most toxic of the gases used in the war, and in addition is highly vesicant, as it produces painful burns at a high dilution. Its physiological action is thought to be due to the fact that it readily penetrates the cell-walls and then, as the result of hydrolysis, hydrochloric acid is formed. Its action is relatively slow and, as a consequence, the vapor can be breathed for some time without any apparent effect it is for this reason a source of great danger. 

Ethyl butyrate hydrolysis Hydrochloric acid 16,800 Steward and Bidwell, 1991... 

Casein hydrolysis Hydrochloric acid 20,600 Braverman and Berk, 1976... 

GattermaDD synthesis A method for the synthesis of aromatic hydroxyaldehydes. E.g. AICI3 is used to bring about the condensation of phenol with a mixture of gaseous hydrochloric acid and hydrocyanic acid an aldimine hydrochloride is formed and on hydrolysis gives p-hydroxybenzaldehyde... 

Hoesch synthesis A variation of the Gattermann synthesis of hydroxy-aldehydes, this reaction has been widely applied to the synthesis of anthocyanidins. It consists of the condensation of polyhydric phenols with nitriles by the action of hydrochloric acid (with or without ZnCl2 as a catalyst). This gives an iminehydrochloride which on hydrolysis with water gives the hydroxy-ketone. 

This process goes on until (if alkali is added) the final product is [Sn(OH) ] . (If alkali is not added, hydrolysis ultimately gives the hydrated oxide in accordance with the equation above.) The hydrolysis can be suppressed by addition of hydrochloric acid, and with excess of this, hexachlorostannic(l V) acid is formed ... 

Here again the simple formulation [Sb ] is used to represent all the cationic species present.) The hydrolysis is reversible and the precipitate dissolves in hydrochloric acid and the trichloride is reformed. This reaction is in sharp contrast to the reactions of phosphorus(III) chloride. 

The existence of anode and cathode areas can be seen by the following experiment. A few drops of phenolphthalein are added to a solution of potassium hexacyanoferrate(III) and hydrochloric acid added, drop by drop, until the solution is colourless. (The phenolphthalein turns pink due to hydrolysis of the potassium hexacyano-ferrate(III).) Drops of this solution, about 1 cm in diameter, are now placed on a sheet of freshly abraded steel when pink cathode areas and blue anode areas appear. 

Hydrolysis of Potassium Ethyl Sulphate. Dissolve about i g. of the crystals in about 4 ml. of cold distilled water, and divide the solution into two portions, a) To one portion, add barium chloride solution. If pure potassium ethyl sulphate were used, no precipitate should now form, as barium ethyl sulphate is soluble in water. Actually however, almost all samples of potassium ethyl sulphate contain traces of potassium hydrogen sulphate formed by slight hydrolysis of the ethyl compound during the evaporation of its solution, and barium chloride almost invariably gives a faint precipitate of barium sulphate. b) To the second portion, add 2-3 drops of concentrated hydrochloric acid, and boil the mixture gently for about one minute. Cool, add distilled water if necessary until the solution has its former volume, and then add barium chloride as before. A markedly heavier precipitate of barium sulphate separates. The hydrolysis of the potassium ethyl sulphate is hastened considerably by the presence of the free acid Caustic alkalis have a similar, but not quite so rapid an effect. 

Hydrolysis of Benzonitrile. Benzonitrile is moderately readily hydrolysed by 10% aqueous sodium hydroxide, but only slowly by hydrochloric acid (cf. p. 122). Ready hydrolysis is obtained by boiling the nitrile under reflux... 

Ketonic Hydrolysis. Hot dilute caustic alkalis or hydrochloric acid first hydrolyse off the ethyl group, and then remove carbon dioxide, a mono- or di-substituted acetone being thus obtained ... 

Vinylacetic acid is obtained by the hydrolysis of aljyl cyanide with concentrated hydrochloric acid ... 

Sulphonamides are most readily identified by hydrolysis with concentrated hydrochloric acid or with 80 per cent, sulphuric acid (for experimental details, see Section K.,7,12) ... 

The disadvantages attending the use of acetic anhydride alone are absent when the acetylation is conducted in aqueous solution according to the following procedure. The amine is dissolved in water containing one equivalent of hydrochloric acid, slightly more than one equivalent of acetic anhydride is added to the solution, followed by enough sodium acetate to neutralise the hydrochloric acid, and the mixture is shaken. The free amine which is liberated is at once acetylated. It must be pointed out that the hydrolysis of acetic anhydride at room temperature is extremely slow and that the free amine reacts much more readily with the anhydride than does the water this forms the experimental basis for the above excellent method of acetylation. 

Hydrolysis of p-tolunitrile to p-toluic acid. Boil a mixture of 5 g. of p-tolunitrile, 80 ml. of 10 per cent, aqueous sodium hydroxide solution and 15 ml. of alcohol under a reflux condenser. (The alcohol is added to prevent the nitrile, which volatUises in the steam, from crystalhsing in the condenser it also increases the speed of hydrolysis. The alcohol may be omitted in the hydrolysis of nitriles which are hquid at the ordinary temperature, e.g., benzo-nitrUe.) The solution becomes clear after heating for about 1 hour, but continue the boiling for a total period of 1 - 5 hours to ensure complete hydrolysis. Detach the condenser and boil the solution for a few minutes in the open flask to remove dissolved ammonia and incidentally some of the alcohol CAUTION /). Cool, and add concentrated hydrochloric acid until precipitation of the p-toluic acid is complete. When cold, filter off the p-toluic acid with suction and wash with a little cold water. Recrystallise from a mixture of equal volumes of water and alcohol (methylated spirit) or from benzene. The yield of p-toluic acid, m.p. 178°, is 5-5 g. 

Hydrolysis of benzonitrile to benzoic acid. BoU 5 -1 g. (5 ml.) of benzo-nitrUe and 80 ml. of 10 per cent, sodium hydroxide solution in a 250 ml. round-bottomed flask fitted with a reflux water condenser until the condensed liquid contains no oUy drops (about 45 minutes). Remove the condenser, and boU the solution in an open flask for a few minutes to remove free ammonia. Cool the liquid, and add concentrated hydrochloric acid, cautiously with shaking, until precipitation of benzoic acid is complete. Cool, filter the benzoic acid with suction, and wash with cold water dry upon filter paper in the air. The benzoic acid (5-8 g.) thus obtained should be pure (m.p. 121°). Recrystal-lise a small quantity from hot water and redetermine the m.p. 

The hydrolysis of arylacetonitriles may be arrest at the arylacetamide stage by treatment with concentrated hydrochloric acid at about 40° thus benzyl cyanide yields phenylacetamlde ... 

Hydrolysis of benzyl cyanide to phenylacetamide. In a 1500 ml. three-necked flask, provided with a thermometer, reflux condenser and efficient mechanical stirrer, place 100 g. (98 ml.) of benzyl]cyanide and 400 ml. of concentrated hydrochloric acid. Immerse the flask in a water bath at 40°. and stir the mixture vigorously the benzyl cyanide passes into solution within 20-40 minutes and the temperature of the reaction mixture rises to about 50°, Continue the stirring for an additional 20-30 minutes after the mixture is homogeneous. Replace the warm water in the bath by tap water at 15°, replace the thermometer by a dropping funnel charged with 400 ml. of cold distilled water, and add the latter with stirring crystals commence to separate after about 50-75 ml. have been introduced. When all the water has been run in, cool the mixture externally with ice water for 30 minutes (1), and collect the crude phenylacetamide by filtration at the pump. Remove traces of phenylacetic acid by stirring the wet sohd for about 30 minutes with two 50 ml. portions of cold water dry the crystals at 50-80°. The yield of phenylacetamide, m.p. 154-155°, is 95 g. RecrystaUisation from benzene or rectified spirit raises the m.p. to 156°. 

Hydrolysis of methyl m-nitrobenzoate to m-nitrobenzoic acid. Place 90 -5 g. of methyl m-nitrobenzoate and a solution of 40 g. of sodium hydroxide in 160 ml. of water in a 1-htre round-bottomed flask equipped with a reflux condenser. Heat the mixture to boiling during 5-10 minutes or until the ester has disappeared. Dilute the reaction mixture with an equal volume of water. When cold pour the diluted reaction product, with vigorous stirring, into 125 ml. of concentrated hydrochloric acid. Allow to cool to room temperature, filter the crude acid at the pump and wash it with a httle water. Upon drying at 100°, the crude m-nitrobenzoic acid, which has a pale brownish colour, weighs 80 g. and melts at 140°, Recrystalhsation from 1 per cent, hydrochloric acid afibrds the pure acid, m.p. 141°, as a pale cream sohd the loss of material is about 5 per cent. 

By the action of concentrated hydrochloric acid at about 40° upon aryl-acetonitriles hydrolysis is arrested at the arylacetamide stage (see Section IV, 160 for the preparation of phenylacetamide by this method) ... 

The hydrolysis by alkali is illustrated by the following experimental details for benzamido. Place 3 g. of benzamide and 50 ml. of 10 per cent, sodium hydroxide solution in a 150 ml. conical or round-bottomed flask equipped with a reflux condenser. Boil the mixture gently for 30 minutes ammonia is freely evolved. Detach the condenser and continue the boiling in the open flask for 3-4 minutes to expel the residual ammonia. Cool the solution in ice, and add concentrated hydrochloric acid until the mixture is strongly acidic benzoic acid separates immediately. Leave the mixture in ice until cold, filter at the pump, wash with a little cold water and drain well. RecrystaUise the benzoic acid from hot water. Determine the m.p., and confirm its identity by a mixed m.p. test. 

Hydrolysis of the original compound will confirm its identity. Boil 0-5-1 0 g. of the original substance with 10-20 ml. of concentrated hydrochloric acid under reflux for 2 hours ... 

Benzanilide and similar compounds are very slowly hydrolysed by concentrated hydrochloric acid hydrolysis is quite rapid with 60-70 per cent, sulphuric acid (for experimental details, see Section IV,52). In the preliminary experiment boil 0 5-1 Og. of the compound with 10-20 ml. of dilute sulphuric acid (1 1 by volume) imder reflux for 20-30 minutes. Dilute with 10ml.of water and filteroflfanyacid which may be precipitated if the carboxyhc acid is hquid and volatile, distil it directly from the reaction mixture. Render the residue alkaline and isolate the base as above. 

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). 

Hydrolysis of the azlactone leads to the acylaminooinnamic acid the latter may be be reduced catal3rtlcally (Adams PtOj catalyst 40 lb. p.s.i.) and then hydrolysed by hydrochloric acid to the amino acid. Alternatively, the azlactone (say, of a-benzylaminocinnamic acid) may undergo reduction and cleavage with phosphorus, hydriodic acid and acetic anhydride directly to the a-amino acid (d/ p phenylalanine). 

Hydrolysis of saccharin (o-sulphobenzoic imide) (Section IV, 209) with dilute hydrochloric acid yields acid ammonium 0 sulphobenzoate, w hich upon... 

Benzylidenehydrazinoselenazoies are stable to acids and do not decompose with time. The isopropylidene homologs are only stable in the form of the hydrochloride, and they can undergo acid hydrolysis, thus providing a convenient pathway to the free hydrazine (32). Hydrolysis is carried out w ith hot 2 N hydrochloric acid, which, after recooling and filtration, leads to 2-hydrazinoselenazole hydrochloride, yielding the free base upon neutralization (Scheme 19, Table X-6). 

The a-acetobutyrolactone, with or without isolation, can be used in the preparation of various 5-substituted 2-butanone derivatives, presumably by decarboxylation of the acetoacetic acid obtained by ring hydrolysis. Simple hydrolysis gives 5-hydroxybutan-2-one (158) and acidolysis with hydrochloric acid gives 5-chlorobutan-2-one in good yields (159). 

Microcrystalline ceUulose (MCC) is a partiaUy depolymeri2ed from of ceUulose prepared by the hydrolysis of wood pulp with hydrochloric acid. 

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