Aliphatic cyanides table

This method is particularly suitable for the synthesis of a-ethylenic and aromatic acyl cyanides but it also provides a valuable method of preparing certain aliphatic acyl cyanides (Table 6.6). The reaction fails with acryloyl chloride, sulphonyl chlorides, ethyl chloroformate and oxalyl chloride. 

The physical properties of a number of aliphatic nitriles (cyanides) are given in Table 111,115. 

Other functional groups that are easily differentiated are cyanide (5c =110-120) from isocyanide (5c = 135- 150), thiocyanate (5c =110-120) from isothiocyanate (5c = 125 - 140), cyanate (5c = 105- 120) from isocyanate (5c = 120- 135) and aliphatic C atoms which are bonded to different heteroatoms or substituents (Table 2.2). Thus ether-methoxy generally appears between 5c = 55 and 62, ester-methoxy at 5c = 52 N-methyl generally lies between 5c = 30 and 45 and. S-methyl at about 5c = 25. However, methyl signals at 5c = 20 may also arise from methyl groups attached to C=X or C=C double bonds, e.g. as in acetyl, C//j-CO-. 

The y-keto nitriles shown in Table I were prepared by the cyanide-catalyzed procedure described here. This procedure is generally applicable to the synthesis of y-diketones, y-keto esters, and other y-keto nitriles. However, the addition of 2-furancarboxaldehyde is more difficult, and a somewhat modified procedure should be employed. Although the cyanide-catalyzed reaction is generally limited to aromatic and heterocyclic aldehydes, the addition of aliphatic aldehydes to various Michael acceptors may be accomplished in the presence of thioazolium ions, which are also effective catalysts for the additions. 

Spacer chain catalysts 3, 4, and 19 have been investigated under carefully controlled conditions in which mass transfer is unimportant (Table 5)80). Activity increased as chain length increased. Fig. 7 shows that catalysts 3 and 4 were more active with 17-19% RS than with 7-9% RS for cyanide reaction with 1-bromooctane (Eq. (3)) but not for the slower cyanide reaction with 1-chlorooctane (Eq. (1)). The unusual behavior in the 1-bromooctane reactions must have been due to intraparticle diffusional effects, not to intrinsic reactivity effects. The aliphatic spacer chains made the catalyst more lipophilic, and caused ion transport to become a limiting factor in the case of the 7-9 % RS catalysts. At > 30 % RS organic reactant transport was a rate limiting factor in the 1-bromooctane reations80), In contrast, the rate constants for the 1 -chlorooctane reactions were so small that they were likely limited only by intrinsic reactivity. (The rate constants were even smaller than those for the analogous reactions of 1-bromooctane and of benzyl chloride catalyzed by polystyrene-bound benzyl-... 

The physical properties of cyanoacetic acid [372-09-8] and two of its ester derivatives are listed in Table 11 (82). The parent acid is a strong organic acid with a dissociation constant at 25°C of 3.36 x 103. It is prepared by the reaction of chloroacetic acid with sodium cyanide. It is hygroscopic and highly soluble in alcohols and diethyl ether but insoluble in both aromatic and aliphatic hydrocarbons. It undergoes typical nitrile and acid reactions but the presence of the nitrile and the carboxylic acid on the same carbon cause the hydrogens on C-2 to be readily replaced. The resulting malonic acid derivative decarboxylates to a substituted acrylonitrile ... 

Cyanohydrin Synthesis. Another synthetically useful enzyme that catalyzes carbon—carbon bond formation is oxynitrilase (EC 4.1.2.10). This enzyme catalyzes the addition of cyanides to various aldehydes that may come either in the form of hydrogen cyanide or acetone cyanohydrin (152—158) (Fig. 7). The reaction constitutes a convenient route for the preparation of a-hydroxy acids and p-amino alcohols. Acetone cyanohydrin [75-86-5] can also be used as the cyanide carrier, and is considered to be superior since it does not involve hazardous gaseous HCN and also virtually eliminates the spontaneous nonenzymatic reaction. (R)-oxynitrilase accepts aromatic (97a,b), straight- (97c,e), and branched-chain aliphatic aldehydes, converting them to (R)-cyanohydrins in very good yields and high enantiomeric purity (Table 10). 

It is not possible to construct an invariant nucleophilicity order because different substrates and different conditions lead to different orders of nucleophilicity, but an overall approximate order is NH2 > PhaC > PhNH (aryne mechanism) > ArS > RO > R2NH > ArO > OH > ArNHi > NH3 > 1 > Br > Cl > H2O > ROH. As with aliphatic nucleophilic substitution, nucleophilicity is generally dependent on base strength and nucleophilicity increases as the attacking atom moves down a column of the periodic table, but there are some surprising exceptions, for example, OH, a stronger base than ArO , is a poorer nucleophile. In a series of similar nucleophiles, such as substituted anilines, nucleophilicity is correlated with base strength. Oddly, the cyanide ion is not a nucleophile for aromatic systems, except for sulfonic acid salts and in the von Richter (13-30) and Rosenmund-von Braun (13-8) reactions, which are special cases. 

The results obtained with other a-halonitriles are indicated in Table VII. With the exception of chlorodiphenylacetonitrile, PMR spectra of the resulting complexes indicated attachment of the cobalt atom alpha to the nitrile group. In the case of chlorodiphenylacetonitrile (in 25 ml. benzene), the benzene layer was separated from the yellow-aqueous layer after 1 hour reaction time. Adding ethanol to the benzene solution yielded tetraphenylsuccinonitrile, m.p. 203-4°C. (acetic acid) (205°C. reported) (49), The aqueous layer was worked up in the usual manner to obtain a white solid, exhibiting a single cyanide absorption band at 2130 cm." and a carbonyl absorption at 1575 cm.. The PMR spectrum showed aromatic and aliphatic protons in the ratio 10 1. 

A general method for the preparation of a-cyano ketones from acid halides was developed recently (equation 43).i57.i58 trimethylsilyl cyanide as reagent a great number of acyl cyanides can be prepared under mild conditions in high yield. In particular the synthetically useful aliphatic derivatives have become accessible by this reaction. Table 13 lists examples for aliphatic, a, -unsaturated and benzylic acyl cyanides. The procedure is very simple in that trimethylsilyl cyanide and acid chloride are mixed and kept without solvent. The reaction is followed by IR spectroscopy. As soon as all of the trimethylsilyl cyanide is consumed, the product can be isolated, normally by distillation, or directly used for fruther reactions. 

Table 13 Synthesis of Aliphatic, a. -Unsaturated and Benzylic Acyl Cyanides...

The homopolymerization of aliphatic diisocyanates across their C=N bond is limited to aliphatic 1,2- and 1,3-diisocyanates and cyclohexane-1,2 and 1,3-diisocyanate (3). These diisocyanates are cyclopolymerized by an alternating, intermolecular-intramolecular propagation mechanism, using sodium cyanide as the catalyst. The cyclopolymers obtained in this manner are listed in Table 5. 

---