Calcium carbodiimide

Calcium hydride, for drying of lert-butyl alcohol, 41, 7 CARBODIIMIDE, DrPHENYL-, 43, 31 Carbodiumdes, from isocyanates, 43, 31... 

Out of three phases reported for Ca3N2 [12], to date only the cubic (a) nitride phase is confirmed, crystallizing in the anti-bixbyite type structure. In addition, the carbodiimide nitride Ca4(CN2)N2 [13] may hold for another unconfirmed calcium nitride phase, and Can(CN2)2N6 stands for the ill-defined CauNg [14]. Here we note again that carbon impurities may produce significant difficulties in reactions. 

O-Aryl-A X-dicyclohexylisoureas are synthesized by stirring mixtures of phenols with 2-3 mol equiv. of dicyclohexylcarbodiimide at 45-100 C for 1-3 d. Hydrogenations are accomplished in isopropyl alcohol or ethyl acetate at 20 °C and atmospheric pressure using 200-300 mg of 5% palladium on carbon or on calcium carbonate per 0.02 mol of the phenol. The hydrogenolysis can also be effected with the crude mixture of the O-arylisoureas and the unreacted carlx iimide using as much hydrogen as needed for hydrogenation of the excess carbodiimide. 

Deoxycholic acid Dicyclohexyl carbodiimide Diethyl amine Disofenin Docusate sodium Edamine Exametazime Gluceptate sodium Gluceptate calcium Glucuronic acid Guanidine HCl lofetamine HCl Lactobionic acid Lidofenin Medrofenin Medronate disodium Medronic acid Methyl boronic acid Methyl cellulose Methylene blue... 

Synonyms/Trade Names Amidocyanogen, Carbimide, Carbodiimide, Cyanogen nitride. Hydrogen cyanamide [Note Cyanamide is also a synonym for Calcium cyanamide.] ... 

Scheme 23 Proposed mechanism for calcium-catalyzed hydrophosphination of carbodiimides (for simplicity, coordinated THF is not shown in 12 or related intermediates)...

Hydrophosphination of carbodiimides to yield phosphaguanidines was catalyzed by several related metal complexes. For example, after carbodiimide coordination by the calcium phosphide complex 12 (see Scheme 18 above), P-C bond formation involving a four-centered transition state and rearrangement was proposed to yield the N,N-bound intermediate 13. Addition of the P-H bond across the Ca-N bond, followed by dissociation of the product, then regenerates the phosphide intermediate (Scheme 23) [37]. Related chemistry was reported recently using the calcium phosphide complex Ca(PPh2)2(THF)4 [38]. 

CadmiumfO), 52 Calcium ethoxide, 52 Camphene, 50, 400, 401 Camphor, 217 Camphorquinone, 55 Cannizzaro reaction, 77-78 Carbamates, 346, 377, 378 a-Carbinollactams, 330 Carbodiimides, 45 ( arboelhoxycarbenc, 313... 

Within CaNCN, the NCN anion exists in the so-called carbodiimide form, that is, a linear N=C=N with two N=C double bonds. Thus, calcium "cyanamide" should rather be called a carbodiimide, but the name had been given to CaNCN many years before the crystal structure was clarified. We reiterate that molecular carbodiimide (H-N=C=N-H) is highly unstable. The same (false) naming applies to most other metal "cyanamides" of which most are, in fact, carbodiimides because they contain the N=C=N anion. 

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