Diethylaluminium cyanide
Encyclopedia
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 ketone
s.
, benzene
, hexane
and isopropyl ether. It undergoes hydrolysis
readily and is not compatible with protic solvents.
, although other diorganoaluminum cyanides have had their crystal structures determined. Diorganylaluminum cyanides have the general formula (R2AlCN)n, and they exist as cyclic trimer
s (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:
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:
The purpose of this reaction is to generate alkylnitriles which are precursors to amines, amides, carboxylic acids and esters.
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
for the hydrocyanation
Hydrocyanation
Hydrocyanation is, most fundamentally, the process whereby H+ and –CN ions are added to a molecular substrate. Usually the substrate is an alkene and the product is a nitrile. When –CN is a ligand in a transition metal complex, its basicity makes it difficult to dislodge, so, in this...
of α,β-unsaturated ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
s.
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 tolueneToluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...
, benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
, hexane
Hexane
Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...
and isopropyl ether. It undergoes hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
readily and is not compatible with protic solvents.
- Et3Al + HCN → Et2AlCN + Et-H
Structure
Diethylaluminum cyanide has not been examined by X-ray crystallographyX-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
, although other diorganoaluminum cyanides have had their crystal structures determined. Diorganylaluminum cyanides have the general formula (R2AlCN)n, and they exist as cyclic trimer
Trimer (chemistry)
In chemistry, a trimer is a product derived from three identical precursors. Trimers are typically cyclic. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids. Often, trimerization competes with polymerization....
s (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:
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:
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.The purpose of this reaction is to generate alkylnitriles which are precursors to amines, amides, carboxylic acids and esters.