White cyanide

White brass White chocolate White cyanide White Diamonds White dross... 

Sodium cyanide [143-33-9] NaCN, is a white cubic crystalline soHd commonly called white cyanide. It was first prepared in 1834 by heating Pmssian blue, a mixture of cyanogen compounds of iron, and sodium carbonate and extracting sodium cyanide from the cooled mixture using alcohol. Sodium cyanide remained a laboratory curiosity until 1887, when a process was patented for the extraction of gold and silver from ores by means of a dilute solution of cyanide (see Metallurgy, extractive). A mixture of sodium and potassium cyanides, produced by Edenmeyer s improvement of the Rodgers process, was marketed in 1890. 

Formula NaCN MW 49.02 CAS [143-33-9] Structure and functional group Na+CN, ionic bond between Na" " and CN, a face-centered-cubic (fee) crystal lattice structure similar to that of sodium chloride Synonyms Cyanobrik Cyanogran white cyanide... 

Cyanide species. Aqueous HCN and CN" decompose (Hg )2 into metallic Hg and [Hg(CN)2]. Mercuiy(II) forms the same readily soluble, un-ionized, white cyanide. Aqueous HCN and HgO provide a good route to this. The firmly bound, relatively non-toxic [Hg(CN)2] releases very little of the highly poisonous Hg " and CN". 

Copperil) cyanide. CuCN (and copperil) thiocyanate), are similarly obtained as white precipitates on adding cyanide and thiocyanate ions (not in excess) respectively to copper(II) salts ... 

In the former, it gives precipitates with halides (except the fluoride), cyanides, thiocyanates, chromates(VI), phosphate(V), and most ions of organic acids. The silver salts of organic acids are obtained as white precipitates on adding silver nitrate to a neutral solution of the acid. These silver salts on ignition leave silver. When this reaction is carried out quantitatively, it provides a means of determining the basicity of the acid... 

REACTIONS AND IDENTIFICATION 325 drop. JNote that the white precipitate of silver salts turns black (showing the presence of silver cyanide). Now add an excess of mercurous nitrate the black precipitate redissolves, but the silver halide remains undissolved. 

Vinylacetic acid. Place 134 g. (161 ml.) of allyl cyanide (3) and 200 ml. of concentrated hydrochloric acid in a 1-htre round-bottomed flask attached to a reflux condenser. Warm the mixture cautiously with a small flame and shake from time to time. After 7-10 minutes, a vigorous reaction sets in and the mixture refluxes remove the flame and cool the flask, if necessary, in cold water. Ammonium chloride crystallises out. When the reaction subsides, reflux the mixture for 15 minutes. Then add 200 ml. of water, cool and separate the upper layer of acid. Extract the aqueous layer with three 100 ml. portions of ether. Combine the acid and the ether extracts, and remove the ether under atmospheric pressure in a 250 ml. Claisen flask with fractionating side arm (compare Fig. II, 13, 4) continue the heating on a water bath until the temperature of the vapour reaches 70°. Allow the apparatus to cool and distil under diminished pressure (compare Fig. II, 20, 1) , collect the fraction (a) distilling up to 71°/14 mm. and (6) at 72-74°/14 mm. (chiefly at 72 5°/ 14 mm.). A dark residue (about 10 ml.) and some white sohd ( crotonio acid) remains in the flask. Fraction (6) weighs 100 g. and is analytically pure vinylacetic acid. Fraction (a) weighs about 50 g. and separates into two layers remove the water layer, dry with anhydrous sodium sulphate and distil from a 50 ml. Claisen flask with fractionating side arm a further 15 g. of reasonably pure acid, b.p. 69-70°/12 mm., is obtained. 

In a 500 ml. round-bottomed flask place 65 ml. of rectified spirit, 50 g. (47 5 ml.) of pure benzaldehyde (1) and a solution of 5 g. of sodium cyanide (96-98 per cent.) CAUTION) in 50 ml, of water. Attach a reflux condenser (preferably of the double surface type) and boil the mixture gently for half an hour (2). Cool the contents of the flask (preferably in an ice bath). Filter the crude benzoin, wash it with cold water, drain well (3) and dry. The yield of crude benzoin, which is white or pale yellow in colour, is 45 g. 

This product is sufficiently pure for the preparation of phenylacetic acid and its ethyl ester, but it contains some benzyl tso-cyanide and usually develops an appreciable colour on standing. The following procedure removes the iso-cyanide and gives a stable water-white compound. Shake the once-distilled benzyl cyanide vigorously for 5 minutes with an equal volume of warm (60°) 60 per cent, sulphuric acid (prepared by adding 55 ml. of concentrated sulphuric acid to 100 ml. of water). Separate the benzyl cyanide, wash it with an equal volume of sa+urated sodium bicarbonate solution and then with an equal volume of half-saturated sodium chloride solution- Dry with anhydrous magnesium sulphate and distil under reduced pressure. The loss in washing is very small (compare n-Butyl Cyanide, Section 111,113, in which concentrated hydrochloric acid is employed). 

Platinum is a beautiful silvery-white metal, when pure, and is malleable and ductile. It has a coefficient of expansion almost equal to that of soda-lime-silica glass, and is therefore used to make sealed electrodes in glass systems. The metal does not oxidize in air at any temperature, but is corroded by halogens, cyanides, sulfur, and caustic alkalis. 

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequendy used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkaU catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonittile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkaU metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Grignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

Mercuric Cyanides. Mercuric cyanide7, Hg(CN)2, is a white tetragonal crystalline compound, Httle used except to a small degree as an antiseptic. It is prepared by reaction of an aqueous slurry of yellow mercuric oxide (the red is less reactive) with excess hydrogen cyanide. The mixture is heated to 95°C, filtered, crystallized, isolated, and dried. Its solubihty in water is 10% at 25°C. 

Mercuric o s.ycy2inide[1335-31 -5] or basic mercuric cyanide, Hg(CN)2 HgO, is prepared in the same manner as the normal cyanide, except that the mercuric oxide is present in excess. The oxycyanide is white and crystalline but only one-tenth as soluble in water as the normal cyanide. Because this compound is explosive, it normally is suppHed as a 1 2 mixture of oxycyanide to cyanide. 

Cyanide iron blues can be prepared by several methods. The most common one is the indirect, two-step process. In the first step, a white precipitate (Berlin white), is produced by the reaction of sodium, potassium, or ammonium ferrocyanide and ferrous sulfate ... 

Silver Chloride. Silver chloride, AgCl, is a white precipitate that forms when chloride ion is added to a silver nitrate solution. The order of solubility of the three silver halides is Cl" > Br" > I. Because of the formation of complexes, silver chloride is soluble in solutions containing excess chloride and in solutions of cyanide, thiosulfate, and ammonia. Silver chloride is insoluble in nitric and dilute sulfuric acid. Treatment with concentrated sulfuric acid gives silver sulfate. 

Cobalt(II) oxalate [814-89-1], C0C2O4, is a pink to white crystalline material that absorbs moisture to form the dihydrate. It precipitates as the tetrahydrate on reaction of cobalt salt solutions and oxaUc acid or alkaline oxalates. The material is insoluble in water, but dissolves in acid, ammonium salt solutions, and ammonia solution. It is used in the production of cobalt powders for metallurgy and catalysis, and is a stabilizer for hydrogen cyanide. 

Potassium cyanide [151 -50-8] KCN, a white crystalline, deUquescent soHd, was initially used as a flux, andlater for electroplating, which is the single greatest use in the 1990s. The demand for potassium cyanide was met by the ferrocyanide process until the latter part of the nineteenth century, when the extraordinary demands of the gold mining industry for alkah cyanide resulted in the development of direct synthesis processes. When cheaper sodium cyanide became available, potassium cyanide was displaced in many uses. With the decline in the use of alkah cyanides for plating the demand for potassium cyanide continues to decline. The total world production in 1990 was estimated at about 4500 t, down from 7300 t in 1976. 

Lithium cyanide [2408-36-8] mbidium cyanide [19073-56 ] and cesium cyanide [21159-32-0] are white or colorless salts, isomorphous with potassium cyanide. In physical and chemical properties these cyanides closely resemble sodium and potassium cyanide. As of this writing these cyanides have no industrial uses. 

Silver cyanide [506-64-9] M 133.9, m dec at 320 , d 3.95. POISONOUS white or grayish white powder. Stir thoroughly with H2O, filter, wash well with EtOH and dry in air in the dark. It is very insoluble in H2O (0.000023g in lOOmL H2O) but is soluble in HCN or aqueous KCN to form the soluble Ag(CN) complex. [Chem Ber 72 299 I939 J Am Chem Soc 52 184 1930.]... 

Zinc cyanide [557-21-1] M 117.4, m 800"(dec), d 1.852. It is a POISONOUS white powder which becomes black on standing if Mg(OH)2 and carbonate are not removed in the preparation. Thus wash well with H2O, then well with EtOH, Et20 and dry in air at 50°. Analyse by titrating the cyanide with standard AgN03. Other likely impurities are ZnCl2, MgCl2 and traces of basic zinc cyanide the first two salts can be washed out. It is soluble in aq KCN solns. However, if purified in this way Zn(CN)2 is not reactive in the Gattermann synthesis. For this the salt should contain at least 0.33 mols of KCl or NaCl which will allow the reaction to proceed faster. [J Am Chem Soc 45 2375 1923, 60 1699 1938-, Org Synth Coll Vol III 549 1955.]... 

Adiponitrile (Tetramethylene cyanide) CN(CH,)4CN Can behave as a cyanide when ingested or otherwise absorbed into the body Combustion products may contain HCN Water-white, practically odourless liquid Elash point 93°C Specific gravity 0.97 Vapour density 3.7... 

Calcium cyanide Ca(CN)2 Reacts with air moisture to release HCN. If finely ground and the relative humidity of the air is >35%, this can occur fairly rapidly Releases HCN slowly on contact with water or CO2, or rapidly with acids Do not handle with bare hands Nonflammable white powder or crystals... 

Potassium cyanide KCN On exposure to air, gradually decomposes to release HCN Poisonous by ingestion, inhalation or skin absorption Do not handle with bare hands. Strong solutions may be corrosive to the skin Nonflammable white lumps or crystals Eaint odour of bitter almonds Completely water soluble... 

Sodium cyanide NaCN Poisonous by inhalation, ingestion or skin absorption Do not handle with bare hands Releases HCN slowly with water, more rapidly with acids Nonflammable white granules, fused pieces or eggs Odourless when dry slight almond odour in damp air Completely water soluble... 

Chemical Designations - Synonyms Cupricin Cuprous Cyanide Chemical Formula CuCN. Observable Characteristics - Physical State (as normally shipped) powder Color white Odor Data not available. 

Thiocyanates and selenocyanates can be made by fusing the corresponding cyanide with S or Se. The SCN and SeCN ions are both linear, like OCN . (See p, 779 for TeCN ) Treatment of KSCN with dry KHSO4 produces free isothiocyanic acid HNCS, a white crystalline solid which is stable below 0° but which decomposes rapidly at room temperatures to HCN and a yellow solid H2C2N2S3. Thiocyanic acid, HSCN, (like HOCN) has not been prepared... 

Iodide ions reduce Cu to Cu , and attempts to prepare copper(ll) iodide therefore result in the formation of Cul. (In a quite analogous way attempts to prepare copper(ll) cyanide yield CuCN instead.) In fact it is the electronegative fluorine which fails to form a salt with copper(l), the other 3 halides being white insoluble compounds precipitated from aqueous solutions by the reduction of the Cu halide. By contrast, silver(l) provides (for the only time in this triad) 4 well-characterized halides. All except Agl have the rock-salt structure (p. 242). Increasing covalency from chloride to iodide is reflected in the deepening colour white yellow, as the... 

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