Acid hydrolysis sulphates

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). 

Waters of pH less than 6 may be expected to be corrosive, but, because any weak acids present in the solution may not be fully ionised, it does not follow that water of pH greater than 7 will not be corrosive. Mine waters are particularly corrosive to cast iron, often to such an extent as to preclude its use with them, because of their relatively high acid content, derived from the hydrolysis of ferric salts of the strong acids, mainly sulphate, and because the ferric ion can act as a powerful cathodic depolariser. 

The use of differential pulse polarography to determine neomycin sulphate in aqueous solutions has been described by Siegerman et all2. Following acid hydrolysis of neomycin, the solution was adjusted to pH 4 and 0.1M acetate... 

Table 12.11 Yield of phosphate from organic and inorganic salts with (MgSO ) and without (no MgSO ) addition of magnesium sulphate and with hydrol) and Without (no hydrol) final acidic hydrolysis step. All yields are percentage of theoretical value 100 indicates theoretical yield (95-105%)...

Other reagents which may be applied to the volumetric determination of sulphuric acid and sulphates are barium chromate and benzidine. In the case of the former, the solution of sulphate is precipitated by a solution of barium chromate in hydrochloric acid on subsequent neutralisation of the filtrate, a quantity of chromic acid, equivalent to the barium sulphate which has been precipitated, remains in solution and may be estimated iodometrically.6 Benzidine, on the other hand, is an organic base which forms a very sparingly soluble sulphate the solution of mineral sulphate is treated with a solution of benzidine hydrochloride and the precipitated benzidine sulphate removed by filtration when subsequently suspended in pure water the benzidine sulphate undergoes hydrolysis to a sufficient extent to permit titration of the sulphuric acid with standard alkali.7 Lead nitrate may also be... 

Glucose syrups, also known as com syrups in the United States, are defined by the European Commission (EC) as a refined, concentrated aqueous solution of D(+)-glucose, maltose and other polymers of D-glucose obtained by the controlled partial hydrolysis of starch (Howling, 1984). Glucose syrups were fust manufactured industrially in the nineteenth century by acid hydrolysis of starch. Hydrochloric acid was normally used, because sulphuric acid caused haze in syrups due to insoluble sulphates. The source of starch can vary in the United States corn is widely used, whereas in other parts of the world wheat, potato and cassava starch are also employed. Acid hydrolysis of starch is still used today. The method is non-specific, but if conditions are tightly controlled, it is possible to make products with a reasonably consistent carbohydrate profile. 

The synthesis of the partially methylated glucoside, methyl 2,3-di-O-methyl-a-D-glucopyranoside (34) (Expt 5.121) also utilises the 4,6-O-benzylidene derivative (27), which is first converted into the 2,3-di-O-methyl derivative (33) by reaction with dimethyl sulphate in the presence of sodium hydroxide. Selective removal of the acetal grouping is achieved by mild acid hydrolysis the methyl ether groups are stable under both acidic and basic conditions. 

Figure 8.6 Graph of kobs versus [SO42 ], showing the catalytic effect of added sulphate in the acid hydrolysis of acetylcholine...

The product is a sulphuric acid ester or sulpho acid which is susceptible to acid hydrolysis, reverting to the alcohol and free sulphuric acid. Since the rate of hydrolysis is dependent on the concentration of the acid, the hydrolysis reaction is effectively self-catalysing so that the sulpho acid must be neutralised as quickly as possible after manufacture to prevent reversion. This simple chemistry has a profound effect on the manufacture, use and economics of alkyl sulphates. 

The reason for improved current efficiency lies in the fact that mixed solutions of sulphuric acid and sulphates have a lower concentration of free sulphuric acid, so hydrolysis of persulphuric acid and persulphatcs proceeds at a much slower rate which results in considerably less Caro s acid being formed. 

Recently, a new and efficient synthesis of cyprodime from naltrexone (2) has been reported [73], Firstly, the tetrazolyl ether (27) was formed by reaction of naltrexone with 5-chloro-l-phenyl-1 Ff-tetrazole [74], Catalytic hydrogenation afforded 3-deoxynaltrexone (28) which was methylated with dimethyl sulphate to give the enol ether (29). Acid hydrolysis gave the known morphinanone (30) [75] which was treated with activated zinc and ammonium chloride to yield the phenol (31). 4-O-Methylation with phenyltri-methylammonium chloride afforded cyprodime (23, Scheme 3.4) [75],... 

The primary metabolite of benzene is phenol. Phenol is excreted as glucuronide and sulphate conjugates in urine. Total phenolic metabolites (phenol, phenyl sulfate, and phenyl glucuronide) have been determined by hydrolyzing urine samples either enzymatically or by acid, then extracting the phenol with solvent. Phenol is then measured by GC or HPLC techniques. Enzymatic hydrolysis coupled with GC/FID has been reported the detection limit is 1 mg/L and recovery is excellent (92-98%) (Buchet 1988). Acid hydrolysis followed by HPLC provides quantitative recovery ( 100%) and a detection limit of 0.01 nmol/g (Murray and Adams 1988). Sulfate and glucuronide conjugates... 

A. Karlsson and S. K. Singh, Acid hydrolysis of sulphated polysaccharides. Desulphation and the effect of molecular mass, Carbohydr. Polym., 38 (1999) 7-15. 

In those cases where a suitable antibody for radioimmunoassay is not available, a full multi-component screening procedure is necessary, and also needs to be undertaken as a confirmatory test in cases where the nature of the anabolic steroid is not known. The full analysis involves the separation of the glucuronic acid and sulphate conjugate fractions and their separate hydrolysis followed by GC-MS of their silyl or methoxime-silyl derivatives. It should be noted that the sulphatase in Helix pomatia will not hydrolyse the sulphate conjugates of the 1713-hydroxy steroids, which require mild acid hydrolysis. 

Neighbouring-group participation by a 5a-acetoxy-group in the substitution of a 3fi-OR group is paralleled by Sa-acetylthio-groups. The crystalline 3a,5a-cyclic onium perchlorate (31) was generated by reaction of the 3j9-hydroxy-compound (29) with acetic anhydride-sulphuric acid [via the 3/1-acetyl sulphate (30)], followed by the addition of perchloric acid. Hydrolysis of the onium salt gave the 3a-acetoxy-5a-thiol (32). 

The resultant sulphate ester can be converted to the alcohol by acid hydrolysis. If an acid-sensitive group is present, this hydrolysis is still successful through use of a catalytic amount of sulphuric acid in the presence of 0.5-1.0 equivalents of water with tetrahydrofuran as solvent. The use of base in the formation of the cyclic sulphates themselves can also alleviate problems associated with acid-sensitive groups [117,118]. 

There is abundant evidence that oxidizing agents attack the cystine linkage, although the nature of the reaction is obscure. Hydrogen peroxide will, under certain conditions, oxidize all the sulphur with the formation of sulphuric acid or sulphates. Alexander, Hudson, and Fox Biochem. J., 1946, 50, 27) showed that peracetic acid and other peracids could oxidize all the disulphide groups. A product is obtained which, after acid hydrolysis. 

The circulins—As early as 1949, Peterson and Reineke characterized circulin as its sulphate. Total hydrolysis yielded D-leucine, L-threonine and L-K,y-diaminobutyric acid together with an optically active isomer of pelargonic acid. The existence of two components, found by Peterson and Reineke was later confirmed by the chromatographic separation of crude circulin into two major components, named circulin A and circulin B. In addition there was evidence for at least three other ninhydrin-positive, biologically active entities. In the hydrolysate of circulin A, L-isoleucine was found besides the amino acids previously reported . Quantitative amino acid analysis showed circulin A and B to be composed of L-a,y-diamino-butyric acid, L-threonine, D-leucine, L-isoleucine and ( + )-6-methyloctanoic acid in the molar ratio 6 2 1 1 1. After partial acid hydrolysis, fractionation and structure determination of the resulting peptides, circulin A and circulin B were formulated as cyclodecapeptides . Very recently, however, Japanese workers have revised the structure of circulin A. According to them, circulin A differs from colistin A only by a replacement of L-leucine in the latter by L-isoleucine Figure 1.7). 

The ionised carotenoid sulphate may be converted into the hydrogen sulphate by ion exchange. Hydrolysis of the sulphate may be accomplished enzymatically, or the sulphate group may alternatively be removed by acid hydrolysis [68]. 

Methylphenobarbital can also be prepared by the interaction of ethylphenyl malonie ester and dicyandiamide when it results into the formation of 5-ethyl-5-phenyl-3-cyano barbituric acid, which on methylation with dimethyl sulphate yields 5-ethyl-5-phenyl-3-cyano-1-methyl barbituric acid. This on acid hydrolysis converts the cyano moiety at position 3 into a free COOH group which on decarboxylation finally gives methylphenobarbital. 

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