Lithium cyanide

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. 

Lithium cyanide melts at 160°C. In the fused state the specific gravity at 18°C is 1.075. It is highly hygroscopic. Rubidium cyanide is not hygroscopic and is insoluble in alcohol or ether. Cesium cyanide is highly hygroscopic. 

Lithium cyanide decomposes to cyanamide and carbon below about 600°C. This decomposition is similar to the aLkaline-earth cyanides (67). Iron accelerates decomposition and, when heated with 10% iron at 500°C for 15 h, lithium cyanide is completely converted to lithium cyanamide [2408-36-8]. 

The nucleophilic acylation of 2-phenylpropanal or 3-phenyI-2-butanone with cyano(trimethyl-silyloxy)phenylmethyllithium proceeds with high Cram selectivity6. The primary addition product 7, after silyl migration and loss of lithium cyanide, gives the a-silyloxy ketones 86. 

Beckman rearrangement of nitrone (262) into amide (263) occurs in the reaction with lithium cyanide. However, this reaction gives lactam (264) instead of the expected 2-cyanopyrrolidine 1-oxide (265) (Scheme 2.96) (473). 

Lithium cobalt dioxide, uses, 7 24 It Lithium complex greases, 15 243 Lithium compounds, 20 598-599. See also Organolithium compounds inorganic, 15 136-142 uses for, 15 134 Lithium cyanide, 8 194 Lithium 5—alumina, 2 406t... 

O-silylierte, -acetylierle oder -benzoylierte 2-Hydroxy-carbonsaure-nitrile erhalt man ohne Katalysator und bei 20° aus aliphatischen und aromatischen Aldehyden sowie aus aliphatischcn und a, /J-ungesat-tigtcn Ketonen in einer einfach durchzufuhrenden Eintopf-Reaktion mit Lithium-cyanid und Chlor-tri-methyl-silan, Acetylchlorid oder Benzoylchlorid in THF6. 

Stereoselective conversion of 3,4-disubstituted-l,2-dithietane 1,1-dioxides 114 into symmetrical (Z)-alkenes 115 has been reported. When substituted 1,2-dithietane 1,1-dioxides 114 having a reactive thiosulfonate group in the four-membered ring were treated with lithium cyanide, the alkenes 115a-d were obtained with high (Z)-selectivity and high chemical yield (Equation 15) <1996BSF515>. 

Figure 10.45 also shows that lithium dialkyl cuprates in solutions containing lithium iodide or lithium cyanide—in addition to the dimeric or monomeric Gilman cuprates presented in Figure 10.44—may contain the following species the contact ion pairs A and C in diethyl... 

On the other hand, the cyclopropanone hemiacetal 3 did not react with nucleophilic lithium reagents such as lithium cyanide 16), ethynyllithium 16) or aryllithium 17). 

Trimethylsilyl cyanide has been prepared in modest yield by the action of hexamethyldisilazane on hydrogen cyanide8 and the reaction of silver cyanide with trimethylchlorosilane.6,7 It has been prepared in good yield by the treatment of preformed lithium cyanide (from LiH and HCN) with trimethylchlorosilane in ether.7 The procedure described here not only affords trimethylsilyl cyanide in good yield, but also avoids the use of hydrogen cyanide and the need for Schlenk ware. 

A small quantity of tetrahydrofuran remains complexed in the solid lithium cyanide and is separated later in the preparation. 

This operation must be performed rapidly to avoid water absorption by the hygroscopic lithium cyanide. 

The reaction of N-tosyl vinyl sulfoximines 236 with lithium cyanide in DMF at room temperature for 1 h gave the vinyl nitriles 254 in good yields.117 Treatment of 236 with lithium dimethylphosphonate in THF at -78 °C to room temperature gave moderate yields of the vinyl phosphonates 255.117 These yields could be improved to 54-64% by isolation of the initial Michael adducts by quenching these reactions at -20 °C and then treatment of these products with sodium methoxide in methanol at reflux. These reactions proceed via the intermediates 256 and 257. 

Lithium cyanide has not been isolated, but Varet6 has determined its heat of formation from the hydroxide and hydrocyanic acid ... 

Diethyl phosphorocyanidate adds to a,/J-unsaturated aldehydes or ketones in the presence of lithium cyanide in a 1,2-fashion28. Boron trifluoride-diethyl ether complex catalyzed rearrangement of these allylic phosphates shows high E selectivity (>85 15) for the adducts derived from aldehydes and Z selectivity (>90 10) for ketone adducts. The selectivity of the rearrangement can be explained by assuming a chairlike transition state, in which the sterically more demanding x-substituent occupies the quasi-equatorial position. The steric requirement decreases in the order of R1 > CN > H. Thus, the cyano substituent occupies the quasi-equatorial position in the aldehyde-derived adduct (R1 = H), but the quasi-axial position in the ketone-derived adduct (R1 = CH3, C6H5). 

Single carbons can be added as cyanide using Acetone Cyanohydrin, " diethylaluminum cyanide (eq 6), or Lithium Cyanide or as methyl groups using an organocuprate (eq 7). A single carbon may be added with dithiane salts and an example of addition of a substituted 1,3-Dithiane to O-benzyl glycidol is shown in eq 8. ... 

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