Hydrolysis of cyanides

The successful results and the green credentials of the process (water as cosolvent and only the nontoxic titanium dioxide as final residue) make this reaction an excellent, cheaper, and favorable alternative to the classical Strecker synthesis, which also requires the hydrolysis of cyanide to the amido group (Scheme 14.8c). 

Conversion of existing functions include the oxidation of aliphatic or aromatic side-chains, one of the earliest preparative techniques of triazole chemistry. Hydrolysis of cyanides obtained by displacement of halo, nitro and diazo groups is of comparable importance. 

Enzymes catalyzing the hydrolysis of cyanide had already been identified earlier. Here too, two different types can be distinguished. The enzyme cyanide hydratase [formamide hydrolase (E. C. 4.2.1.66)] can be found in various fungi1311. It catalyzes the hydration of cyanide to formamide ... 

Hydrolysis of cyanide to CO2H and of bromide to OH can both be accomplished in one step. ... 

Direct disconnection is possible at this oxidation level since CO2, especially convenient as solid dry ice , reacts once only with Grignard reagents or RLi (iv). This method complements hydrolysis of cyanides (v) since the disconnection is the same but the polarity is different. Hence the r-alkyl acid (19) could not be made by the cyanide method as displacement at the tertiary centre would be difficult. The Grignard method works well. ... 

Another important aspect is the enzymatic hydrolysis of cyanide for the detoxification of industrial effluents [653-656]. 

PR Kurek. Oxidation and Hydrolysis of Cyanides Using Metal Chelates on Supports of Metal Oxide Solid Solutions. US Patent 5,476,596, December 19, 1995. 

Solutions of ammonium cyanide NH4CN, sodium cyanide NaCN, potassium cyanide KCN, calcium cyanide Ca(CN)2 and barium cyanide Ba(CN)2 are alkaline (due to the hydrolysis of cyanides) and attack aluminium. The addition of 0.5% sodium sUicate inhibits this attack. 

The kinetics of the acid hydrolysis of cyanide ion were studied several decades ago. The kinetics of base hydrolysis of cyanide ion have only recently been investigated, though the reaction products were established as formate ion and ammonia many years ago. Rates of alkaline hydrolysis are first-order in cyanide ion, zero-order in hydroxide. The rate-determining step cannot therefore be attack of hydroxide at cyanide ion. However, both water attack at cyanide or hydroxide attack at hydrocyanic acid are consistent with the reported rate law. The overall kinetic pattern for the reaction, including the... 

By hydrolysis of alkyl cyanides (or nitriles) with alkali hydroxide solutions, for example ... 

For practice, the student should carry out both alkaUne (compare Section 111,83) and acid hydrolysis of acetonitrile, n-valeronitrile (n-butyl cyanide) and n-capronitrile (n-amyl cyanide). 

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

By the hydrolysis of nitriles. The nitriles may be easily prepared either from amines by the Sandmeyer reaction (Section IV,66) or by the action of cuprous cyanide upon aryl halides (compare Section IV,163). Benzyl cyanide... 

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 phenylacetic acid. Into a 500 ml. round-bottomed flask, provided with a reflux condenser, place 100 ml. 

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 a nitrile to an amide. Warm a solution of 1 g. of the nitrile benzyl cyanide) in 4 ml. of concentrated sulphuric acid to 80-90°, and allow the solution to stand for 5 minutes. Cool and pour the solution cautiously into 40 ml. of cold water. Filter oflT the precipitate stir it with 20 ml. of cold 5 per cent, sodium hydroxide solution and filter again. RecrystaUise the amide from dilute alcohol, and determine its m.p. Examine the solubility behaviour and also the action of warm sodium hydroxide solution upon the amide. 

Primary and secondary alkyl halides may be converted to the next higher carboxylic acid by a two step synthetic sequence involving the preparation and hydrolysis of nitriles Nitnles also known as alkyl cyanides are prepared by nucleophilic substitution... 

In the Strecker synthesis an aldehyde is converted to an a ammo acid with one more carbon atom by a two stage procedure m which an a ammo nitrile is an mterme diate The a ammo nitrile is formed by reaction of the aldehyde with ammonia or an ammonium salt and a source of cyanide ion Hydrolysis of the nitrile group to a car boxylic acid function completes the synthesis... 

Dichloroacetic acid is produced in the laboratory by the reaction of chloral hydrate [302-17-0] with sodium cyanide (31). It has been manufactured by the chlorination of acetic and chloroacetic acids (32), reduction of trichloroacetic acid (33), hydrolysis of pentachloroethane [76-01-7] (34), and hydrolysis of dichloroacetyl chloride. Due to similar boiling points, the separation of dichloroacetic acid from chloroacetic acid is not practical by conventional distillation. However, this separation has been accompHshed by the addition of a eotropeforming hydrocarbons such as bromoben2ene (35) or by distillation of the methyl or ethyl ester. 

Other methods of production iaclude hydrolysis of glycolonittile [107-16 ] with an acid (eg, H PO or H2SO2) having a piC of about 1.5—2.5 at temperatures between 100—150°C glycolonittile produced by reaction of formaldehyde with hydrogen cyanide recovery from sugar juices and hydrolysis of monohalogenated acetic acid. None of these has been commercially and economically attractive. 

A solution of sodium cyanide [143-33-9] (ca 25%) in water is heated to 65—70°C in a stainless steel reaction vessel. An aqueous solution of sodium chloroacetate [3926-62-3] is then added slowly with stirring. The temperature must not exceed 90°C. Stirring is maintained at this temperature for one hour. Particular care must be taken to ensure that the hydrogen cyanide, which is formed continuously in small amounts, is trapped and neutrali2ed. The solution of sodium cyanoacetate [1071 -36-9] is concentrated by evaporation under vacuum and then transferred to a glass-lined reaction vessel for hydrolysis of the cyano group and esterification. The alcohol and mineral acid (weight ratio 1 2 to 1 3) are introduced in such a manner that the temperature does not rise above 60—80°C. For each mole of ester, ca 1.2 moles of alcohol are added. 

Physical properties for naphthalene mono-, di-, tri-, and tetracarboxyhc acids are summari2ed in Table 9. Most of the naphthalene di- or polycarboxyLic acids have been made by simple routes such as the oxidation of the appropriate dior polymethylnaphthalenes, or by complex routes, eg, the Sandmeyer reaction of the selected antinonaphthalenesulfonic acid, to give a cyanonaphthalenesulfonic acid followed by fusion of the latter with an alkah cyanide, with simultaneous or subsequent hydrolysis of the nitrile groups. 

Chemical Synthesis. The first synthesis of ascorbic acid was reported ia 1933 by Reichsteia and co-workers (14,39—42) (Fig. 4). Similar, iadependent reports pubHshed by Haworth and co-workers followed shordy after this work (13,43—45). L-Xylose (16) was converted by way of its osazone (17) iato L-xylosone (18), which reacted with hydrogen cyanide forming L-xylonitfile (19). L-Xylonitfile cyclized under mild conditions to the cycloimine of L-ascorbic acid. Hydrolysis of the cycloimine yielded L-ascorbic acid. The yield for the conversion of L-xylosone to L-ascorbic acid was ca 40%. 

Although a C—CN bond is normally strong, one or two cyano groups in TCNE can be replaced easily, about as easily as the one in an acyl cyanide. The replacing group can be hydroxyl, alkoxyl, amino, or a nucleophilic aryl group. Thus hydrolysis of TCNE under neutral or mildly acidic conditions leads to tricyanoethenol [27062-39-17, a strong acid isolated only in the form of salts (18). 

This reaction and the subsequent hydrolysis should be carried out in a good hood as some hydrogen cyanide is liberated. The sodium cyanide used was the technical cyan-egg, containing about 92-95 per cent of cyanide. 

Mandelic acid is best prepared by the hydrolysis of mandeloni-trile with hydrochloric acid. The mandelonitrile has been prepared from amygdalin, by the action of hydrocyanic acid on benzaldehyde, and by the action of sodium or potassium cyanide on the sodium bisulfite addition product of benzaldehyde. ... 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

Cyanides are dangerously toxic materials that can cause instantaneous death. They occur in a number of industrial situations but are commonly associated with plating operations, and sludges and baths from such sources. Cyanide is extremely soluble and many cyanide compounds, when mixed with acid, release deadly hydrogen cyanide gas. Cyanide is sometimes formed during the combustion of various nitrile, cyanohydrin, and methacrylate compounds. Cyanides (CN ) are commonly treated by chlorine oxidation to the less toxic cyanate (CNO ) form, then acid hydrolyzed to COj and N. Obviously, care should be taken that the cyanide oxidation is complete prior to acid hydrolysis of the cyanate. 

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