METAL THIOCYANATES

The a-thiocyanatoketones are easily obtainable from a-halocarbonyl compounds and metal thiocyanates (sodium, potassium, barium, or lead thiocyanate) (416, 484, 519, 659) in an alcoholic solution. Yields ranged from 80 to 95%. They are very sensitive substances that isomerize when reacted upon by acids, bases, or labile hydrogen and sulfur compounds. 

Thiocyanates are rather stable to air, oxidation, and dilute nitric acid. Of considerable practical importance are the reactions of thiocyanate with metal cations. Silver, mercury, lead, and cuprous thiocyanates precipitate. Many metals form complexes. The deep red complex of ferric iron with thiocyanate, [Fe(SCN)g] , is an effective iadicator for either ion. Various metal thiocyanate complexes with transition metals can be extracted iato organic solvents. 

Rhodan-ion, n. thiocyanogen ion, CNS -kali, -kalium, n, potassium thiocyanate, -kalzium, n. calcium thiocyanate, -kupfer, n. cupric thiocyanate, copper(II) thiocyanate. -iSsung, /. thiocyanate solution, -metall, n. (metallic) thiocyanate, -methyl, n. methyl thiocyanate, -natrium, n, sodium thiocyanate, -nickel, m. nickel thiocyanate, -quecksilber, n. mercury thiocyanate, -salz, n. thiocyanate, -sdure, /. (Org. Chem.) thiocyan(at)o acid, -tonerde, /. aluminum thiocyanate. 

Tri-n-butyl phosphate, ( -C4H9)3P04. This solvent is useful for the extraction of metal thiocyanate complexes, of nitrates from nitric acid solution (e.g. cerium, thallium, and uranium), of chloride complexes, and of acetic acid from aqueous solution. In the analysis of steel, iron(III) may be removed as the soluble iron(III) thiocyanate . The solvent is non-volatile, non-flammable, and rapid in its action. 

The solution should be free from the following, which either interfere or lead to an unsatisfactory deposit silver, mercury, bismuth, selenium, tellurium, arsenic, antimony, tin, molybdenum, gold and the platinum metals, thiocyanate, chloride, oxidising agents such as oxides of nitrogen, or excessive amounts of iron(III), nitrate or nitric acid. Chloride ion is avoided because Cu( I) is stabilised as a chloro-complex and remains in solution to be re-oxidised at the anode unless hydrazinium chloride is added as depolariser. 

It is expected, therefore, that the cyclic hexamer also exhibits a characteristic tendency to complex with cations. In fact, the addition of an acetonitrile solution of metal thiocyanates to a solution of the cyclic hexamer in the same solvent shifted the carbonyl absorption to a lower wave number46,52 The shift values depended upon the kind of metal ions present, and the largest shift value of 40 cm-1 was observed for barium thiocyanate (molar ratio of Ba2+/hexamer = 10). In addition to the shift of the carbonyl absorption, the intensities of the C—O-C stretching vibrations around 1200 cm-1 varied appreciably. 

Proton noise decoupled 13C-NMR spectra of equimolar mixtures of the cyclic hexamer and metal thiocyanates showed that the signals of the carbonyl carbon and two methine carbons gave downfield shifts upon the addition of metal thiocyanates, while those of the three methylene carbons of the tetrahydropyran ring gave upfield... 

In recent years research in the field of transition-metal thiocyanates and selenocyanates received a new impetus, because of the partly interesting physical properties of such crystalline species. A review on Cd and Hg thiocyanate systems collects and sorts results of this endeavor.371 The nonlinear optical (NLO) properties of Cd thiocyanate and selenocyanate systems and criteria for the design of NLO crystals (crystal engineering), especially, have been discussed afterwards.372 Further contributions to the field have also been described.37, 374 The structure of mercury chlorothiocyanate has been re-determined.375... 

See Potassium chlorate Metal thiocyanates See related cyano compounds... 

See METAL THIOCYANATES Oxidants, MOLTEN SALT BATHS See other REDOX REACTIONS... 

See also MOLTEN SALT BATHS, METAL THIOCYANATES... 

A-METAL DERIVATIVES, METAL HALIDES METAL POLYHALOHALOGENATES, METAL THIOCYANATES and for the oxosalts ... 

Metal thiocyanates are oxidised explosively by chlorates or nitrates when fused, or if intimately mixed, at 400°C or on spark or flame ignition [1], Nitric acid violently oxidised an aqueous thiocyanate solution [2],... 

See Nitric acid Metal thiocyanate Sodium nitrite Potassium thiocyanate... 

It is worth mentioning that fluorothiocarbonyl isothiocyanate, produced by the reaction of CSFCl with metal thiocyanates (52), combines with chlorine quantitatively at low temperatures at the C=S double bond, without suffering an attack on the isothiocyanate group 21) ... 

Magnesium nitrate, Tin(ll) fluoride, 4693 Manganese(lV) oxide, Calcium hydride, 4705 Molybdenum(VI) oxide, Graphite, 4717 Nitric acid, Formaldehyde, 4436 Nitric acid, Formic acid, 4436 Nitric acid, Formic acid. Urea, 4436 Nitric acid, Metal thiocyanate, 4436 Oxalic acid, Urea, 0725 Ozone, Acetylene, 4846... 

Venkataramaiah and Rao, Nature, 1923, in, 775. Eor further description of the thiocyanates mentioned here and other metallic thiocyanates, see under the various metals in other volumes of this Series. 

The 2-chloro substituent may be exchanged for various nucleophiles. The 2-alkoxy derivatives were formed with alkali metal alkoxides,98,1 12,255,273 the 2-amino derivatives were formed with ammonia and amines,79,98,255, 260.283,285,286 t]ie 2-hydrazino derivatives were formed with hydrazine,98,255,283,287 and the 2-thiocyanatb derivatives were formed with alkali metal thiocyanates.283 2,3-Dichloro-4-oxo-4//-pyrido[l,2-fl]pyrimi-dine in phenol reacts with gaseous ammonia to yield a mixture of the 2-phenoxy and 2-amino derivatives, whereas with sodium hydroxide, the 2-phenoxy compound is obtained.255... 

The action of bromine upon various metallic thiocyanates gives thiocyanogen in better yield, but few solvents yield... 

See also METAL THIOCYANATES, MOLTEN SALT BATHS... 

---