Diethylaluminium cyanide

Diethylaluminium cyanide
IUPAC name diethylalumanylformonitrile
Other names Cyanodiethyl Aluminum (cyano-κC)diethyl-Aluminum (cyano-C)diethyl-Aluminum Cyanodiethyl-(7CI,8CI) Aluminum Cyanodiethylallane Cyanodiethylaluminum Diethylaluminum Cyanide
Identifiers
CAS number	5804-85-3 Y
Properties
Molecular formula	C4H10AlCN Et2AlCN
Molar mass	111.12 g/mol
Appearance	colorless liquid
Density	0.864 g/cm3 at (25 °C) liquid
Boiling point	162 °C/0.02 mmHg (435.15 K) °F)
Solubility in water	Benzene, Toluene, diisopropyl ether
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Diethylaluminum cyanide is the organoaluminum compound with formula ((C₂H₅)₂AlCN)_n. This compound is usually handled as a solution in toluene. This compound is a reagent for the hydrocyanation of α,β-unsaturated ketones.^{[1] [2] [3][4][5]}

Synthesis

Diethylaluminum cyanide was originally produced in 1966. It is generated by the treatment of triethylaluminum with a slight excess of hydrogen cyanide. The product is typically stored in ampoules because it is highly toxic. It dissolves in toluene, benzene, hexane and isopropyl ether. It undergoes hydrolysis readily and is not compatible with protic solvents.

Et₃Al + HCN → Et₂AlCN + Et-H

Structure

Diethylaluminum cyanide has not been examined by X-ray crystallography, although other diorganoaluminum cyanides have had their crystal structures determined. Diorganylaluminum cyanides have the general formula (R₂AlCN)_n, and they exist as cyclic trimers (n = 3) or tetramers (n = 4). In these oligomers one finds AlCN---Al linkages.

A compound similar to diethylaluminum cyanide is bis(trimethylsilyl)methyl]aluminium cyanide, ((Me₃Si)₂CH)₂AlCN, which has been shown crystallographically to exist as a trimer with the following structure:^[6]

More recently, bis(hydrocarbyl)aluminium cyanides have been structurally characterized, such as bis(tert-butyl)aluminium cyanide, tBu₂AlCN, which forms a tetramer in the crystalline phase:^[7][8]

Uses

Diethylaluminum cyanide is used for hydrocyanation of α,β- unsaturated ketones. The reaction is influenced by the basicity of the solvent. This effect arises from the Lewis acidic qualities of the reagent.^[9] The purpose of this reaction is to generate alkylnitriles which are precursors to amines, amides, carboxylic acids and esters.

References

1. ^ Nagata, W (1966). "Alkylaluminum cyanides as potent reagents for hydrocyanation". Tetrahedron Letters 7 (18): 1913–1918. doi:10.1016/S0040-4039(00)76271-X. 
2. ^ http://www.sigmaaldrich.com/catalog/ProductDetail.dolang=en&N4=276863%7CALDRICH&N5=SEARCH_CONCAT_PNO%7CBRAND_KEY&F=SPEC
3. ^ Uhl, Werner; SchüTz, Uwe; Hiller, Wolfgang; Heckel, Maximilian (1995). "Synthese und Kristallstruktur des trimeren [(Me3Si)2CH]2Al?CN". Zeitschrift für anorganische und allgemeine Chemie 621: 823–828. doi:10.1002/zaac.19956210521. 
4. ^ Wade, K.; Wyatt, B. K. (1969). "Reactions of organoaluminium compounds with cyanides. Part III. Reactions of trimethylaluminium, triethylaluminium, dimethylaluminium hydride, and diethylaluminium hydride with dimethylcyanamide". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 1121–1124. doi:10.1039/J19690001121. 
5. ^ Coates, G. E.; Mukherjee, R. N. (1963). "35. Dimethylaluminium cyanide and its gallium, indium, and thallium analogues; beryllium and methylberyllium cyanide". Journal of the Chemical Society (Resumed): 229–232. doi:10.1039/JR9630000229. 
6. ^ Uhl, Werner; Schütz, Uwe; Hiller, Wolfgang; Heckel, Maximilian (1995). "Synthese und Kristallstruktur des trimeren [(Me₃Si)₂CH]₂Al—CN". Z. anorg. allg. Chem. 621 (5): 823–828. doi:10.1002/zaac.19956210521. 
7. ^ Uhl, Werner; Matar, Madhat (2004). "Hydroalumination of Nitriles and Isonitriles". Z. Naturforsch., B: Chem. Sci. 59 (11/12): 1214–1222. http://www.znaturforsch.com/ab/v59b/59b1214.pdf. 
8. ^ Uhl, Werner; Schütz, Uwe; Hiller, Wolfgang; Heckel, Maximilian (2005). "Synthese und Kristallstruktur des trimeren [(Me₃Si)₂CH]₂Al—CN". Z. Naturforsch., B: Chem. Sci. 60 (2): 155–163. http://www.znaturforsch.com/ab/v60b/60b0155.pdf. 
9. ^ W. Nagata and M. Yoshioka (1988), "Diethylaluminum cyanide", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0436 ; Coll. Vol. 6: 436