The Reduction Products of Certain Cyclic Methyleneamines. Part II.by John Graymore, J Chem Soc 1353 (1932)The method employed for the preparation of secondary amines (
JCS 1931, 1490) has been extended to other cyclic methyleneamines.
In all the cases examined, the condensation 3 R-NH
2 + 3 CH
2O
(R-N=CH
2)
3 + 3 H
2O proceeds normally to give a practically theoretical yield of the cyclic base.
These bases are stable in neutral or alkaline solution, but readily decompose in the presence of acid, rapidly on warming, evolving formaldehyde and giving the corresponding salt of the original primary amine used.
They all form urates soluble in water, but the solubility of these is not so great as in the previous cases studied. The bases form oily additive products with bromine and iodine, the investigation of which is not yet complete.
Reduction with zinc dust and hydrochloric acid proceeds smoothly, the secondary alkylmethylamines being the main product, (R-N=CH
2)
3 + 3 H
2 3 R-NH-CH
3ExperimentalTriisobutyltrimethylenetriamine20g of freshly distilled isobutylamine (bp 68°C), well cooled, were added gradually with shaking to an ice-cold solution of formaldehyde (21g of 40%). Immediate separation of an oily base took place. Caustic soda was added to complete the separation and the base was removed and finally dehydrated over barium oxide. It distilled from barium oxide as a colourless liquid, bp 255°C, having the characteristic odour of these compounds, d
18° 0.8220).
The picrate crystallised from alcohol in squat prisms, mp 107°C. It decomposed in boiling water, evolving formaldehyde; isobutylamine picrate, mp 148°C, was isolated from the solution.
The oxalate, precipitated by the base from a concentrated alcoholic solution of oxalic acid, crystallised from aqueous alcohol in pearly plates, mp 165°C.
ReductionThe freshly distilled base (20 g) was dissolved in well-cooled dilute hydrochloric acid, and zinc dust (20g) added. Hydrochloric acid (110g, (d 1.16, diluted to 1 in 3) was added slowly with cooling. After 15 minutes, the mixture was very gradually heated to boiling (2 hours). Ebullition was maintained until any trace of formaldehyde perceptible had disappeared. The mixture of amines was distilled from excess of caustic soda into hydrochloric acid. Diethylisobutylamine was isolated from this solution in the form of its nitroso-derivative, bp 185-180°C (
Stoermer and Von Lepel, Ber., 1896, 29, 2110), converted into the hydrochloride, mp 177°C, by heating with alcoholic hydrogen chloride, and regenerated therefrom (12g), bp 76-78°C.
The picrate crystallised from alcohol in yellow needles, mp 103°C. The hydrobromide, prepared by adding a slight excess of the base to hydrobromic acid and evaporating the solution in a vacuum, crystallised from water in needles, mp 203°C.
2,4-Dinitromethylisobutylaniline crystallised quickly from a warm solution of 2,4-dinitrochlorobenzene in alcohol on addition of a slight excess of methylisobutylaniline; mp 92-93°C after recrystallisation from hot alcohol.
Tri-n-butyltrimethylenetriamineThis was prepared from n-butylamine (20g) and 40% formaldehyde (21g) in the cold. The oily base, dried over barium oxide for 2 days, had bp 285°C and d
17° 0.8550.
The picrate was obtained from alcoholic solution as a syrup which crystallised after several days, and was recrystallized from aqueous alcohol, forming needles, mp 75-70°C, slightly soluble in water. It decomposed when heated with water, evolving formaldehyde. The hydrochloride, obtained as a feathery mass from the base and hydrogen chloride in benzene, was extremely deliquescent.
Reduction This was done, and the methyl-n-butylamine isolated, as in the case of the isobutyl compound. The nitrosoaniline was a yellow oil, bp 198°C, and the hydrochloride formed somewhat deliquescent needles, mp 170°C The recovered base (12-13g) had 90-91°C.
Methyl-n-butylamine picrate was prepared in alcoholic solution and crystallised in needles, mp 110-111°C, slightly soluble in water.
TriisoamyltrimethylenetriamineIsoamylamine (20g) readily condensed with formaldehycle (18g of 40% solution) on gradual admixture with much cooling and shaking. Heat was evolved and the cyclic base separated immediately. It was purified as in the previous cases and obtained as a rather unpleasant-smelling oil, bp 299-300°C, d
18° 0.8250, insoluble in water but soluble in alcohol and ether.
The oxalate, precipitated from a concentrated alcoholic solution of oxalic acid, crystallised from aqueous alcohol in light leaflets, mp 115°C, sparingly soluble in cold water. It decomposed in hot aqueous solution, giving off formaldehyde; isoamylamine oxalate, mp 165°C, was isolated from the residual liquor. The picrate separated from alcoholic solution as a syrup and crystallised from acetone, cooled in a freezing mixture, in tufts of needles, mp 75°C (indistinct), soluble in water and alcohol. The hydrochloride, obtained from benzene solution, was so deliquescent that its mp could not readily be determined. The urate was a white amorphous powder only slightly soluble in water. It decomposed at a high temperature without melting. Boiled with water, it decomposed, evolving formaldehyde.
ReductionThis was done as in the previous cases and gave 10g of methylisoamylamine, bp 108°C, isolated through the nitrosoamine, bp 204-205°C and the crystalline hydrochloride, mp 178°C.
Methylisoamylamine hydrobromide crystallised from an aqueous solution of the components in needles, mp 183°C, soluble in alcohol and water.
TribenzyltrimethylenetriamineThis was prepared from 20g of benzylamine and 18g of 40% formaldehyde solution in a freezing mixture, separation of the treacly base being completed by addition of caustic soda. The base was extracted and dried (48 hours over barium oxide) in ether, distilled above 200°C, and again dried over barium oxide ; on redistillation it had bp 240°C and d
15° 1.05 (yield, 80%). It is insoluble in water but soluble in alcohol, ether, and benzene.
The oxalate, precipitated from alcoholic solution and recrystallised from aqueous alcohol, formed plates, mp 135°C (dec.) Its aqueous solution evolved formaldehyde when boiled, and benzylamine oxalate, mp 201°C, was isolated from the residual liquor.
Reduction20g of tribenzyltrimethylenetriamine were dissolved in cold dilute hydrochloric acid, 30g of zinc dust added, followed gradually by 420ml of dilute hydrochloric acid (1:3). Reduction was carried out as before and the mixed amines were collected in hydrochloric acid. The hydrochlorides obtained from the solution were dissolved in water and shaken with benzenesulfonyl chloride and sodium hydroxide, an excess of the latter being finally added, and the mixture warmed to dissolve the sulphonamide of the primary amine. The insoluble benzenesulfonbenzylmethylamide crystallised from acetone in tiny hard granules, mp 130°C, soluble in alcohol. From the filtrate, benzenesulphonbenzylamide, mp 88°C, was obtained by precipitation with hydrochloric acid and recrystallisation from acetone.
p-Toluenesulphonbenzylmethylamide crystallised from acetone in squat prisms, mp 92°C.
2,4-Dinitromethylbenzylaniline separated slowly in long yellow needles from an alcoholic solution of 2,4-dinitrochlorobenzene containing a slight excess of benzylmethylamine; mp 140°C after recrystallisation from alcohol.
The method is being extended to other primary aliphatic and aromatic amines.