Primary amines with substituted benzenes

Among chemical methods for the separation of amines, those of Hinsberg (reaction with / -toluenesulfonyl chloride) and of Alexander (94) (reaction with 3-nitrophthalic anhydride) are most commonly used. Tertiary amines do not react with the reagents mentioned and they can be separated after the reaction — for example, by extraction. Derivatives of primary amines with p-toluenesulfonyl chloride are soluble in alkali hydroxide solutions, in contrast to sulfonamides of secondary amines this is utilized for their separation. When primary and secondary amines are separated by reacting them with 3-nitrophthalic anhydride, use is made of the fact that only phthal-imine acids derived from primary amines can be cyclized. Practical utilization of both procedures is demonstrated by the separated of a mixture of aniline, ethylaniline, and diethylaniline. However, it should be mentioned that in a number of cases the procedures fail or do not lead to a sufficiently sharp separation. Negatively substituted amines which do not react with / -toluenesulfonyl chloride can be separated with 3-nitrophthalic anhydride. Some p-toluenesulfonamides of primary amines are poorly soluble in alkali. The derivative of primary amine with 3-nitrophthalic anhydride is cyclized merely by boiling in benzene, and the phthalimide formed is soluble in benzene and can be isolated together with the tertiary amine. 

A,A-Dialkylformamide acetals (7) react with primary amines to give the corresponding amidines (8). Kinetics of the reaction of a range of such acetals with ring-substituted anilines—previously measured in neutral solvents such as methanol or benzene —have been extended to pyridine solution. In pyridine, the reactions are irreversible, with first-order kinetics in each reactant, and mechanistically different from those in non-basic solvents. Two mechanisms are proposed to explain Hammett plots for a range of anilines, in which the p value switches from negative to positive at a cr value of ca 0.5. The pyridine solvent substantially enhances the rate in the case of very weakly basic anilines. 

The formation of a-naphthols of type 189 from 1-alkyl-substituted salts 30, on heating with dimethylamine hydrochloride in ethanol, occurs by another mechanism and will be explained in Section III,C,4,b,i. The interaction of l-aryl-3-carboxy-substituted salts 62 with secondary amines in benzene is initiated probably as in the reaction of these salts with primary amines, and the attack by the secondary amine on position 3 is the primary step of this reaction. However, since protonation of the intermediate anion 190, a masked acyl anion, becomes difficult, an interaction of this anion with the carbonyl group of the benzophenone fragment occurs (86KGS125). The enamines 191 thus formed are usually hydrolyzed on purification, yielding five-membered cyclic acyloins 192. 

Reductive amination. Conversion of ketones or aldehydes to amines is usually accomplished by reduction of the carbonyl compound with sodium cyanoborohydride in the presence of an amine (Borch reduction, 4, 448-449). However, yields are generally poor in reactions of hindered or acid-sensitive ketones, aromatic amines, or trifluoromethyl ketones. Yields can be improved markedly by treatment of the ketone and amine first with TiCl4 or Ti(0-i -Pr)42 in CH2C12 or benzene to form the imine or enamine and then with NaCNBH3 in CH3OH to effect reduction. Note that primary amines can be obtained by use of hexamethyldisilazane as a substitute for ammonia (last example). 

Benzene-1.3,5-triol (phloroglucinol) undergoes reaction with benzofuroxan in methanol with a primary amine as base to give phenazine-l,3-diol 5,10-dioxide.Phenazine-2,3-diol 5,10-dioxides are also synthesized by the reaction of benzene-1,2,4-triol with 6-substituted benzo-furoxans. ... 

Nucleophilic reactions take place on the hetero ring of isoquinoline, preferably in the 1-position. For instance, the Chichibabin amination with NaNH2 in liquid ammonia yields 1-aminoisoquinoline 5. The Ziegler reaction with w-butyllithium furnishes the 1-substituted product 7 as with quinoline, benzene ring annulation stabilizes the primary addition product 6 (1,2-dihydroisoquinoline), which can be isolated and dehydrogenated to 7 by nitro compoxmds ... 

Ortho and / flra-substituted acids give different straight lines owing to chelation and steric hindrance. To account for slopes less than —1, we must assume that the formation constant of the ion pair, the medium effects, or both depend on the strength of the acid. Mead found linear correlations between heats of neutralisation of amines with trichloroacetic add in benzene and base strength in water primary, secondary and tertiary amines fell on parallel lines. 

R = H) with primary amines results in cleavage of the thiazole ring and gives substituted imidazoles, whereas treatment of these compounds with benzene-diazonium chloride yields the 2-phenylazo-derivatives (71 R = PhN=N). ... 

We had initially anticipated preparing the mono-substituted crown ether derivative via a capped structure formed by reaction of the crown ether bis-anhydride with a suitable amino-alcohol. Previous work with bis-primary amines indicate that capping was a favorable process (25), but the seconda amino alcohol produced a complex mixture of products which resisted characterization. Moreover, a brute force approach using stoichiometric p-(N-methylaminomethyl)hydroxymethyl benzene and crown ether e ydride gave the required triacid (below R = Me) in poor yield mixture with bis-amides and apparently epimeriz materials. 

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