1,1-Dinitriles

Glutarlc acid (n =3), pimelic acid (n = 5) and suberic acid (n = 6) may be obtained from the corresponding dibromides. These are converted by aqueous - alcoholic potas-sium or sodium cyanide into the dinitriles, and this latter are smoothly hydrolysed by 50 per cent, sulphuric acid into the dicarboxybc acids ... 

Pimelic acid. This may be prepared from 1 5-peiitanediol or tetra-hydropyran, through the dibromide (Sections 111,35 and 111,37) and dinitrile exactly as described for Suberic Acid. An alternative method for the preparation of 1 5-dibromopentane, together with full details of the subsequent steps, is given in the following Section. 

Enone formation-aromatization has been used for the synthesis of 7-hydro-xyalkavinone (716)[456]. The isotlavone 717 was prepared by the elimina-tion[457]. The unsaturated 5-keto allyl esters 718 and 719, obtained in two steps from myreene. were subjected to enone formation. The reaction can be carried out even at room temperature using dinitriles such as adiponitrile (720) or 1,6-dicyanohexane as a solvent and a weak ligand to give the pseudo-ionone isomers 721 and 722 without giving an allylated product(458]. 

Although acetonitrile is one of the more stable nitriles, it undergoes typical nitrile reactions and is used to produce many types of nitrogen-containing compounds, eg, amides (15), amines (16,17) higher molecular weight mono- and dinitriles (18,19) halogenated nitriles (20) ketones (21) isocyanates (22) heterocycles, eg, pyridines (23), and imidazolines (24). It can be trimerized to. f-trimethyltriazine (25) and has been telomerized with ethylene (26) and copolymerized with a-epoxides (27). 

Another example is the du Pont process for the production of adiponitrile. Tetrakisarylphosphitenickel(0) compounds are used to affect the hydrocyanation of butadiene. A multistage reaction results in the synthesis of dinitrile, which is ultimately used in the commercial manufacture of nylon-6,6 (144-149). 

In the final step the dinitrile is formed from the anti-Markovrukov addition of hydrogen cyanide [74-90-8] at atmospheric pressure and 30—150°C in the hquid phase with a Ni(0) catalyst. The principal by-product, 2-methylglutaronitrile/4j5 j5 4-ti2-, when hydrogenated using a process similar to that for the conversion of ADN to hexamethylenediamine, produces 2-meth5i-l,5-pentanediamine or 2-methylpentamethylenediamine [15520-10-2] (MPMD), which is also used in the manufacture of polyamides as a comonomer. 

Its manufacture begins with the formation of dodecanedioic acid produced from the trimeri2ation of butadiene in a process identical to that used in the manufacture of nylon-6,12. The other starting material, 1,12-dodecanediamine, is prepared in a two-step process that first converts the dodecanedioic acid to a diamide, and then continues to dehydrate the diamide to the dinitrile. In the second step, the dinitrile is then hydrogenated to the diamine with hydrogen in the presence of a suitable catalyst. 

Then in a series of chemical transformations the diamine or lactam can be prepared from brassyUc acid (177,178). The diamine is formed as described above for the 12-carbon diamine, ie, diacid —> diamide —> dinitrile —> diamine. The lactam is made from the dinitrile as follows. 

Chemical and physical solvent losses can render a process uneconomical. Desirable solvents are good solvents for urea, poor solvents for CA, high boiling, and stable to pyrolysis intermediates, ammonia, oxygen, and heat. Although no perfect solvent has been identified, some solvents, eg, dinitriles (94), pyrrohdinones (95,96), and sulfones (97) largely meet these requirements. 

There are several laboratory methods useful for the preparation of suberic acid. One starting material is 1,6-hexanediol which can be converted to the dibromide with HBr. Reaction of the dibromide with NaCN gives the dinitrile which can be hydrolyzed to suberic acid. The overall yield is 76% (42). Another laboratory method is the condensation of 1,3-cyclohexanedione with ethyl bromoacetate foUowed by reductive cleavage to give suberic acid in 50% yield (43). 

KAISEH - JOHNSON - MIDDLETON Oinilniecyciizatlon Synthesis of heterocycles by cyciizatlon of dinitriles by means of HBr... 

Naphthalenedicarboxylic acid has been prepared by fusing dipotassium 2,6-naphthalenedisulfonate with potassium cyanide to give the corresponding dinitrile, which is hydrolyzed by oxidation of 2-methyl-6-acetylnaphthalene with dilute nitric acid at 200 by the thermal disproportionation of potassium a- or /3-naphthoate to dipotassium 2,6-naphthalenedicarboxylate and naphthalene and by the present method. The present method is much more convenient than earlier methods, if a suitable autoclave is available. 

Cyanogen (Ethane dinitrile, Prussite) (CN)2 Highly poisonous gas similar to HCN Colourless flammable gas with a pungent almondlike odour, becoming acrid in higher concentrations Water soluble Vapour density 1.8... 

Chemical Designations - Synonyms Ethanedenitrite Dicyan Oxalic Acid Dinitrile Oxalonitrile Dicyanogen Chemical Formula (CbOj. 

Elimination of the hydroxyaminomethyl moiety from nitro oxime 15 by treatment with a diazonium salt gave hydrazone 43 (75LA1029) (Scheme 15). The same product was obtained by coupling the diazonium salt with the compound 16. On heating in aniline, oxime 15 was transformed into Schiff base 42. Acylation of the oxime 15 with benzoyl chloride in pyridine led to a mixture of furazan 44 and dinitrile 45. 

With dinitriles a slightly different procedure is necessary due to their water solubility. After the reaction has cooled, 150 ml of chloroform is added to the flask, and this mixture is then poured into saturated salt solution. Enough water is added to dissolve precipitated salt and the chloroform layer is separated. The aqueous layer is extracted once with chloroform. The combined extracts are then washed twice with salt solution, dried, and distilled. 

The solvent for ammonia may have an important influence. In reduction of C,o unsaturated dinitriles to primary amines over ruthenium-on-alumina, ammonia-/-butanol proved the preferred system normal alcohols gave poor rates and secondary alcohols produced N-alkylated products 18). 

Davis and co-workers have carried out the first examples of the Knoevenagel condensation and Robinson annulation reactions [61] in the ionic liquid [HMIM][PFg] (HMIM = l-hexyl-3-methylimidazolium) (Scheme 5.1-33). The Knoevenagel condensation involved the treatment of propane-1,3-dinitrile with a base (glycine) to generate an anion. This anion added to benzaldehyde and, after loss of a water molecule, gave l,l-dicyano-2-phenylethene. The product was separated from the ionic liquid by extraction with toluene. 

The dinitrile 1 (1.5-5.5 g) was dissolved in a mixture of CH2Cl2 (20 mL) and Et20 (200 mL). The solution was cooled in an ice bath to 0 C and a stream of anhyd HBr was bubbled through the solution for about 1.5 h. The solvent was removed under reduced pressure (water pump) to give a crystalline or syrupy residue of the azcpinc hydrobromide 2, which was crystallized (MeOH/acetone/Et20 or MeOH). The free bases 3 were liberated by pouring a solution of the hydrobromide salt in MeOH (10-20 mL) into an excess of aq NaHCOj. The mixture was stirred for 15-30 min, and the free base liberated was removed by filtration, then dried and crystallized (CH2Cl2). 

Molecular ion The molecular ions of aliphatic dinitriles with molecular weights greater than 80 are usually not observed, but... 

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