Sodium hydroxide hydrolysis

Although the preparation of /3-mercaptoethanesulfonicacid through the ammonolysis reaction is the preferred method, it is also possible to prepare the sulfonic acid by the sodium hydroxide hydrolysis of /3-S-thiuronium ethanesulfonate followed by the ion exchange treatment. The resulting acid, however, is generally not as satisfactory as that prepared by the am-monolysis reaction. 

Carbamate pesticides are best analyzed by HPLC using postcolumn deriva-tization technique. Some common carbamate pesticides are listed in Table 2.19.1. Compounds are separated on a C-18 analytical column and then hydrolyzed with 0.05 N sodium hydroxide. Hydrolysis converts the carbamates to their methyl amines which are then reacted with o-phthalaldehyde and 2-mercaptoethanol to form highly fluorescent derivatives. The derivatives are detected by a fluorescence detector. o-Phthaladehyde reaction solution is prepared by mixing a 10-mL aliquot of 1% o-phalaldehyde solution in methanol to 10 mL of acetonitrile containing 100 pL of 2-mercaptoethanol and then diluting to 1 L with 0.05 N sodium borate solution. 

In a similar way, sodium hydroxide hydrolysis of the proerythrinadienone 71 (obtained by VOF3 oxidation of norprotosinomenine trifluoroacetamide) brings about its rearrangement to an intermediate which on reduction gives the di-phenolic dibenzazonine 35a in excellent yield (59) (Scheme 18). In contrast,... 

Hydrolysis of acrylamide homopolymer The synthetic PAM samples and a commercial PAM sample from Polysciences, Inc. with a reported of 5 to 6 x 10 were hydrolyzed in aqueous solutions of 0.250 m sodium hydroxide. Hydrolysis reactions (reaction 4) were conducted under conditions shown in Table 1 utilizing 1000 ml, 3-necked flasks equipped with reflux condensers and overhead stirrers. Nitrogen was bubbled through the solutions during the reaction. At specified intervals, the reaction solutions were precipitated into acetone. The polymers were dissolved and precipitated three times and were further purified by extraction with a 20/80 water/methanol solution to remove residual sodium hydroxide. Six hydrolyzed polyacrylamide samples (Table 1) were prepared from the Polysciences standard having degrees of hydrolysis ranging from 19.2% to 65.7%. 

Reflux Distillation Unit. The apparatus shown in Fig. 38 is a specially designed distillation-unit that can be used for boiling liquids under reflux, followed by distillation. The unit consists of a vertical water-condenser A, the top of which is fused to the side-arm condenser B. The flask C is attached by a cork to A. This apparatus is particularly suitable for the hydrolysis of esters (p. 99) and anilides (p. 109), on a small scale. For example an ester is heated under reflux with sodium hydroxide solution while water is passed through the vertical condenser water is then run out of the vertical condenser and passed through the inclined condenser. The rate of heating is increased and any volatile product will then distil over. 

Although the acetylation of alcohols and amines by acetic anhydride is almost invariably carried out under anhydrous conditions owing to the ready hydrolysis of the anhydride, it has been shown by Chattaway (1931) that phenols, when dissolved in aqueous sodium hydroxide solution and shaken with acetic anhydride, undergo rapid and almost quantitative acetylation if ice is present to keep the temperature low throughout the reaction. The success of this method is due primarily to the acidic nature of the phenols, which enables them to form soluble sodium derivatives, capable of reacting with the acetic... 

Hydrolysis of Aspirin. Gently boil a mixture of i g. of aspirin and 15 ml. of 10% sodium hydroxide solution in a 50 ml. conical flask under reflux for 20 minutes. Then cool the solution thoroughly and add dilute sulphuric acid until the precipitation of the... 

Boil a mixture of 5 ml. (4 g.) of acetonitrile and 75 ml. of 10% aqueous sodium hydroxide solution in a 200 ml. flask under a refluxwater-condenser for 30 minutes, when hydrolysis will be complete. Detach the condenser and boil the solution in the open flask for a few minutes to drive off ull free ammonia. Then cool the solution, and add dilute sulphuric acid (i volume of concentrated acid 2 volumes of water)... 

The addition of the sulphuric acid first neutralises the sodium hydroxide, and then gives a weakly acidic and therefore colourless solution. The sodium derivative (A) then undergoes further partial hydrolysis in order to re-establish the original equilibrium, and the sodium hydroxide thus formed again produces the pink coloration, which increases in depth as the hydrolysis proceeds. 

Hydrolysis to p-Nitroaniline. For this purpose use 70 sulphuric acid, the usual reagent employed for the hydrolysis of anilides (p. 108). Add 5 g. of the recrystallised />-nitro-acetanilide to 30 ml. of 70%sulphuric acid, and boil the mixture gently under a reflux water-condenser for 20 minutes. Then pour the clear hot solution into about 150 ml. of cold water, and finally add an excess of sodium hydroxide solution until precipitation of the yellow p-nitroaniline is complete. Coo the mixture in ice-water if necessary, and then filter at the pump, wash well... 

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... 

Hydrolysis of />-Tolunitrile. As in the case of benzonitrile, alkaline h> drolysis is preferable to hydrolysis by 70% sulphuric acid. Boil a mixture of 5 g. of p-tolunitrile, 75 ml. of 10% aqueous sodium hydroxide solution and 15 ml. of ethanol under a reflux water-condenser. The ethanol is added partly to increase the speed of the hydrolysis, but in particular to prevent the nitrile (which volatilises in the steam) from actually crystallising in the condenser. The solution becomes clear after about i hour s heating, but the boiling should be continued for a total period of 1-5 hours to ensure complete hydrolysis. Then precipitate and isolate the p-toluic acid, CH3CgH4COOH, in precisely the same way as the benzoic acid in the above hydrolysis of benzonitrile. Yield 5 5 g. (almost theoretical). The p-toluic acid has m.p. 178°, and may be recrystallised from a mixture of equal volumes of water and rectified spirit. 

Place I ml. of benzyl alcohol in a boiling-tube and add 6 ml. of 10% sodium hydroxide solution add also 6 ml. of water to moderate the subsequent reaction, otherwise the rise in temperature may cause hydrolysis of some of the ester produced. Now add r-q g. of finely powdered />-nitrobenzoyl chloride, and shake the well-corked tube vigorously. The mixture becomes warm, and the solid ester rapidly... 

Hydrolysis. Ethyl acetoacetate when treated w ith cold dilute sodium hydroxide solution gives the sodium salt of acetoacetic acid. This acid is unstable, and readily breaks down into acetone and carbon dioxide it is of considerable... 

I. Hydrolysis by sodium hydroxide. Classes (B), (C) and (D) hydrolyse thus ... 

Alternatively, to prevent undue hydrolysis, make the solution just alkaline to phcnolphthalein with sodium hydroxide, then just acid with dilute nitric acid, and finally, add a slight excess of ammonia. 

Hydrolysis (or saponification) of n-butyl acetate. Boil 4-5 g. of n-butyl acetate (Section 111,95) with 50 ml. of 10 per cent, sodium hydroxide solution under reflux until the odour of the ester can no longer be detected (about 1 hour). Set the condenser for downward distiUation and coUect the first 10 ml. of distillate. Saturate it with potassium carbonate, aUow to stand for 5 minutes, and withdraw all the Uquid into a small pipette or dropper pipette. AUow the lower layer of carbonate solution to run slowly into a test-tube, and place the upper layer into a small test-tube or weighing bottle. Dry the alcohol with about one quarter of its buUr of anhydrous potassium carbonate. Remove the alcohol with a dropper pipette and divide it into two parts use one portion for the determination of the b.p. by the Siwoloboff method (Section 11,12) and convert the other portion into the 3 5-dinitrobenzoate (Section III, 27) and determine the m.p. 

Aliphatic amides may be hydrolysed by boiling with 10 per cent, sodium hydroxide solution to the corresponding acid (as the sodium salt) the alkahne solution should be acidified with dilute sulphuric acid any water-soluble acid may then be distilled from the solution. Alternatively, hydrolysis may be eflfected with 10-20 per cent, sulphuric acid. The resulting ahphatic acid (usually a liquid) may be characterised as detailed in Section 111,85. 

Polyhydric alcohols are compounds containing two or more hydroxyl groups in the molecule. The two most important are ethylene glycol HOCHjCHjOH (a dihydric alcohol) and glycerol HOCHjCH(OH)CH. OH (a trihydric alcohol). Ethylene glycol may be obtained by the hydrolysis of ethylene dibromide or ethylene dichloride with dilute aqueous sodium hydroxide or sodium carbonate solution ... 

A better method involves the interaction of an alkyl bromide and thiourea to form an alkyl tso-thiourea, followed by hydrolysis of the latter with sodium hydroxide solution, for example ... 

Hydrolysis of benzanilide. Place 5 g. of benzanilide and 50 ml. of 70 per cent, sulphuric acid in a small flask fitted with a reflux condenser, and boU gently for 30 minutes. Some of the benzoio acid will vapourise in the steam and solidify in the condenser. Pour 60 ml. of hot water down the condenser this will dislodge and partially dissolve the benzoic acid. Cool the flask in ice water filter off the benzoic acid (anifine sulphate does not separate at this dilution), wash well with water, drain, dry upon filter paper, and identify by m.p. (121°) and other tests. Render the filtrate alkaline by cautiously adding 10 per cent, sodium hydroxide solution, cool and isolate the aniline by ether extraction. Recover the ether and test the residue for anifine (Section IV,100). 

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. 

Crystalline derivatives, suitable for identification and characterisation are dealt with in Section IV, 114, but the preparation of the following, largely liquid, derivatives will be described in the following Sections. When phenols are dissolved in aqueous sodium hydroxide solution and shaken with acetic anhydride, they undergo rapid and almost quantitative acetylation if the temperature is kept low throughout the reaction. This is because phenols form readily soluble sodium derivatives, which react with acetic anhydride before the latter undergoes appreciable hydrolysis, for example ... 

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. 

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. 

The solution will then contain the free acid and the hydrochloride of the base either of these may separate if sparingly soluble. If a sohd crystallises from the cold solution, filter, test with sodium bicarbonate solution compare Section 111,85, (i) and compare the m.p. with that of the original compound. If it is a hydrolysis product, examine it separately. Otherwise, render the filtrate alkahne with sodium hydroxide solution and extract the base with ether if the presence of the unchanged acyl canpound is suspected, extract the base with weak acid. Identify the base in the usual manner (see Section IV, 100). The acid will be present as the sodium salt in the alkaline extract and may be identified as described in Section IV,175. 

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