Quaternary ammonium iodides, conversion

The conversion of the quaternary ammonium iodide to the hydroxide may also be carried out using a strongly basic ion exchange resin. ... 

Table I. Quaternary Ammonium Iodides Used in the Conversion of Cubic P to SSZ-13 R-N (CH3)3 I Structures...

Aminomethylation of lactone enolates with the Eschenmoser salt followed by neutralization (workup) yields the corresponding Mannich bases. Their conversion to quaternary ammonium iodides followed by treatment with DBU (1,5-diazabicy-clo[5.4.0]undec-5-ene) leads to a-methylene lactones. 

Elimination of the quaternary ammonium salt generally takes place by the E2 mechanism, which requires a strong base. To provide the base, the quaternary ammonium iodide is converted to the hydroxide salt by treatment with silver oxide. Heating of the quatanary ammonium hydroxide results in E2 elimination and formation of an alkene. This elimination of a quaternary ammonium hydroxide is called the Hofinann elimination. Conversion to the hydroxide salt... 

Analytical methods iaclude thin-layer chromatography (69), gas chromatography (70), and specific methods for determining amine oxides ia detergeats (71) and foods (72). Nuclear magnetic resonance (73—75) and mass spectrometry (76) have also been used. A frequentiy used procedure for iadustrial amine oxides (77) iavolves titratioa with hydrochloric acid before and after conversion of the amine to the quaternary ammonium salt by reaction with methyl iodide. A simple, rapid quaHty control procedure has been developed for the deterrniaation of amine oxide and unreacted tertiary amine (78). 

In the case of nicotinamide, the color yield is often low. This problem can be circumvented by either hydrolysis to nicotinic acid or by conversion of the amide to a fluorescent compound. Treatment of nicotinamide with methyl iodide yields the quaternary ammonium salt, /V-methyl nicotinamide (5). Reaction of this compound with acetophenone yields a fluorescent adduct (49). Other carbonyl compounds have also been used (50—54). 

Monoetherification of polyols.12 Monobenzylation and monoallylation of polyols can be conducted conveniently under mild conditions by conversion to the stannylene derivative (dimeric) by di-n-butyltin oxide (5, 189 9, 141). The stannylene is then treated with benzyl bromide or allyl bromide and tetra-n-butylammonium iodide (1 equiv.) in benzene. The same conditions can be used to prepare monomethoxymethyl ethers. Quaternary ammonium bromides are less efficient catalysts than the iodides. These salts also accelerate reaction of stannylenes with acid anhydrides. The mechanism for this activation is not clear it may involve coordination of I" to tin. 

The reaction between alkyl hahdes and ammonia or primary amines is not usually a feasible method for the preparation of primary or secondary amines, since they are stronger bases than ammonia and preferentially attack the substrate. However, the reaction is very useful for the preparation of tertiary amines and quaternary ammonium salts. If ammonia is the nucleophile, the three or four alkyl groups on the nitrogen of the product must be identical. If a primary, secondary, or tertiary amine is used, then different alkyl groups can be placed on the same nitrogen atom. The conversion of tertiary amines to quaternary salts is called the Menshutkin reaction It is sometimes possible to use this method for the preparation of a primary amine by the use of a large excess of ammonia or a secondary amine by the use of a large excess of primary amine. The use of ammonia in methanol with microwave irradiation has also been effective. Microwave irradiation has also been used in reactions of aniline with allyl iodides. A base other than the amine... 

Weinstock and Boekelheide introduced Amberlite IRA-400 (OH ) for conversion of alkyltrimethylammonium iodides into the corresponding quaternary ammonium hydroxides. The procedure is simpler than the conventional silver oxide method and avoids undesirable side reactions sometimes encountered. In the case of a derivative of /3-erythroidine, this technique raised the yield in a Hofmann degradation from 40 to 78%. 

Herzig-Meyer determination of (V-alkyl groups. IV-alkylamines are refluxed with hy-driodic acid and the quaternary alkyl ammonium iodides are pyrolyzed to split off alkyl iodide, which is determined gravimetrically by conversion to silver iodide or titrated as iodate. 

Tetra- -butylammonium fluoride in the method F acts as the ultimate reductant with subsequent oxidation to tri- -butylamine, and a fluoride ion, as strong base, is apparently involved in this conversion. This method was found to be applicable in the homo-couplings of aryl iodides and bromides. Since the use of quaternary ammonium salts as oxidants has not been widely explored, this reaction requires further mechanistic investigations. 

Typical conditions for these processes are simply to stir an aqueous solution of the metal salt of Y with the organic substrate alone, or in a solvent such as chloroform or benzene, in the presence of 5—10 mole % of a quaternary ammonium salt as catalyst. A recent example is to be found in a synthesis of alkyl azides from alkyl iodides (or other halides) using commercially available Aliquat 336 [mainly (1)] as catalyst, and a reaction temperature of 100 °C. The conversion of alkyl methanesulphonates to alkyl halides has been used to synthesize optically active secondary fluorides, chlorides and bromides via an 5 n2 inversion mechanism (the iodides racemize before isolation). Ammonium salt (1), or phosphonium salt (2), are used to catalyse these mesylate displacements. ... 

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