Cyanate tetraethylammonium

In a 100-mL round-bottomed flask equipped with N2 inlet, [W(CO)5(CNEt2)] [BF4] (2.1 g, 4.2 mmol) is added to 30 mL of dichloromethane at — 40 °C, followed by tetraethylammonium cyanate (1.5 g, 8.7 mmol) while stirring. After 30 min, the orange solution is taken directly to column chromatography1411 (silica gel, — 40 °C, column length 40 cm, width 3 cm). Elution with dichloromethane-diethyl ether (1 1) into a cooled (—40 °C) Schlenk tube with N2 inlet yields a dark orange solution, which is reduced in vacuo to 15mL. The product (0.95 g, 54%) is precipitated with 25 mL of pentane at — 40 °C and washed twice with 20 mL of cold pentane. 

Owing to the rapid decomposition of the cyanate ion in water, the use of aprotic solvents was necessary for the preparation of the Ag(NCO)J ion. Since alkali cyanates are poorly soluble in aprotic solvents, the cyanate salts used were the tetraethylammonium, tetramethylammonium and tetraphenylarsonium cyanates. Either dry acetone or acetonitrile could be used as solvent as silver isocyanate was reasonably soluble in both. Once prepared the silver salts were found to be light- and moisture-sensitive.136-137... 

The solubility of the components in the solvent must be sufficient. To improve the solubility, cosolvents can be used. Another possibility is the application of a two-phase system or an emulsion in the presence of phase-transfer catalysts. A two-phase system also has advantages in product isolation and continuous electrolysis procedures. A typical example is the synthesis of p-methoxy benzonitrile by anodic substitution of one methoxy group in 1,4-dimethoxybenzene by the cyanide ion (Eq. 22.21). The homogeneous cyanation system (acetonitrile, tetraethylammonium cyanide) [24] can be efficiently replaced by a phase-transfer system (dichloro-methane, water, sodium cyanide, tetrabutylammonium hydrogen sulfate) [71]. 

Bis[tetraethylammonium] Tetramethylenetetracyanatotelluratc(IV)2 0.95 g (1 mmol) of bis[tetraethylam-monium] tetramethylenetetraiodotellurate(IV) and 0.32 g (4 mmol) of potassium cyanate are added to chloroform, the mixture is stirred at 20° for 2 h, and heated under reflux for 4h. Precipitated potassium iodide is filtered off and the filtrate is concentrated to crystallize the product yield 0.54 g (99%) m.p. 164°. Similarly prepared were the following compounds ... 

Complexes with cyanate were prepared [143] by reaction of anhydrous lanthanide chlorides with an excess of tetraethylammonium cyanate in absolute ethanol. The complex has the formula [(C2H5)4N]3Ln(NCO)6, where Ln = Eu, Gd, Dy, Ho, Er, and Yb and they are indicated to be six-coordinate and cyanate is N-bonded as evidenced by IR spectra [147]. Mixed complexes [(C2H5)4N]3[Ln(NCO)3X3], where Ln = Dy, Er and Yb and X = C1, NCS have been synthesized and they appear to be of six-coordinate [144]. Mixed complexes of the type [(C2H5)4N]3[Ln(NC0)3(N03)3], where Ln = La, Pr, Nd, Sm, Eu, Gd, Er and Yb have been synthesized and the IR spectra shows N-bonded cyanate, bidentate nitrate and the overall coordination number amounting to nine [145]. 

The crystal standard of (7r-cp)2Ti(NCO)2 has been determined and confirms that, in the solid state, the cyanate group is here N-bonded it was only in the last stages of the analysis that the 0-bonded alternative could be finally eliminated (i). Hexa-iV-cyanato complexes of ytterbium, erbium, and neodymium have been reported as quaternary onium salts (16) and reference made to the series of tetraethylammonium salts of [Ln(NCO)0] (Ln = Eu-Yb) (22) these results extend Table XLII. The ESR spectra of series of complexes CuL2(NCO)2 (L = an, or substituted an) have been interpreted to show Cu— N(CO)—Cu bridges with no indication of any Cu-0 interactions (19). The ESCA spectra of [M(NCO)4] (M = Mn, Co, Zn) have been recorded (12). 

A solution of 43.3 g (0.21 mole) of tetraethylammonium bromide in 350 ml of anhydrous methanol is placed on the prepared anhydrous column and eluted to a volume of 21. with absolute methanol. Again a flow rate of 2 drops/ sec is advised. The eluate is concentrated on a rotary evaporator (water aspirator) to a very viscous solution, which is then evaporated to dryness under dynamic vacuum (10- torr) at ambient temperature. The yield, based upon tetraethylammonium bromide, is 27 g (75 %). Further purification was not found necessary, but if additional purification of the products is desired, it can be accomplished by dissolving the product in 150 ml of acetonitrile in a dry-box. The pure cyanate is precipitated by the addition of 200 ml of ethyl acetate. The product is isolated by filtration in a dry-box and dried under dynamic vacuum at ambient temperature. Anal. Calcd. for C9H2oN20 C, 62.79 H, 11.63 N, 16.09 O, 9.40. Found C, 62.7 H, 11.8 N, 16.3 O, 9.3. 

Tetraethylammonium cyanate is a white solid which deliquesces in air but can be stored for an indefinite time in a dry inert atmosphere. It is soluble in... 

A column, identical to that described in part 1 of Sec. A, is packed with 1 lb of IRA-400 resin and charged with 454 g (9.26 moles) of sodium cyanide dissolved in 4 1. of 50% aqueous methanol. The column is then rinsed with 5 1. of anhydrous methanol. A solution of 44 g (0.21 mole) of tetraethylammonium bromide in 400 ml of anhydrous methanol is prepared and placed on the charged anhydrous column. The collection and purification of the tetraethylammonium cyanide are carried out exactly as described for the cyanate, except that purification of the cyanide is always necessary. After the product is isolated from the acetonitrile-ethyl acetate solution, it is dried under dynamic vacuum at ambient temperature for 24 hr. The yield, based on tetraethylammonium bromide, is 20 g (60%). Anal. Calcd. for C9H20N2 C, 69.23 H, 12.82 N, 17.95. Found C, 69.1 H, 12.7 N, 17.7. 

Anhydrous tetraphenylarsonium cyanate is a white solid which is hygroscopic and must be stored in a dry inert atmosphere. It is soluble in ethanol, methanol, and acetonitrile. The compound melts, with decomposition, at ca. 224°. The infrared spectrum, taken as a Nujol mull, exhibits the following bands due to the cyanate fundamental absorptions (incm-i) v(As) at 2140 (s) and d at 622 (s). This spectrum agrees well with a recent spectral study of this compound. Again, as with tetraethylammonium cyanate, Fermi resonance is exhibited in the spectrum of this compound at 1280 (m) and 1192 (m) cm-i. 

In a dry-box, 31.2 g (0.41 mole) of anhydrous ammonium thiocyanate dissolved in 500 ml of anhydrous acetonitrile is combined with a solution of 70.5 g (0.41 mole) of tetraethylammonium cyanate in 200 ml of acetonitrile. The white precipitate which immediately forms is collected on a fine-fritted sin-tered-glass crucible by suction filtration and washed several times with acetonitrile. The product is dried for hr under a dynamic vacuum at ambient temperature. The yield, based on tetraethylammonium cyanate, is 19.7 g (80%). Anal Calcd. for CH4N2O C, 20.00 H, 6.71 N, 46.65 O, 26.64. Found C, 20.2 H, 6.5 N, 46.5 O, 26.8. 

Cobaltaie(l -), dodecacarbonylirontri-, tetraethylammonium, 27 188 Cobaltate(l -), dodecacarbonylirontri-, (triphenylphosphine)gold(l -(-), 27 188 -------, dodecacarbonylrutheniumtri-, tetraethylammonium, 26 358 Copper, (acetonitrile)dodecacarbonyltrico-balt ruthenium-, 26 359 Crystal growth, 26 377 Cyanate, tungsten complex, 26 42 Cycloheptatriene, molybdenum complex, 27 4... 

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