Secondary amines, separation from primary

Method 2. Place a 3 0 g. sample of the mixture of amines in a flask, add 6g. (4-5 ml.) of benzenesulphonyl chloride (or 6 g. of p-toluenesulphonyl chloride) and 100 ml. of a 5 per cent, solution of sodium hydroxide. Stopper the flask and shake vigorously until the odour of the acid chloride has disappeared open the flask occasionally to release the pressure developed by the heat of the reaction. AUow the mixture to cool, and dissolve any insoluble material in 60-75 ml. of ether. If a solid insoluble in both the aqueous and ether layer appears at this point (it is probably the sparingly soluble salt of a primary amine, e.g., a long chain compound of the type CjH5(CH2) NHj), add 25 ml. of water and shake if it does not dissolve, filter it off. Separate the ether and aqueous layers. The ether layer will contain the unchanged tertiary amine and the sulphonamide of the secondary amine. Acidify the alkaline aqueous layer with dilute hydrochloric acid, filter off the sulphonamide of the primary amine, and recrystaUise it from dilute alcohol. Extract the ether layer with sufficient 5 per cent, hydrochloric acid to remove all the tertiary amine present. Evaporate the ether to obtain the sulphonamide of the secondary amine recrystaUise it from alcohol or dilute alcohol. FinaUy, render the hydrochloric acid extract alkaline by the addition of dilute sodium hydroxide solution, and isolate the tertiary amine. 

Derivatives with 3-nitrophthalic anhydride. 3-Nitrophthalic anhydride reacts with primary and secondary amines to yield nitro-phthalamic acids it does not react with tertiary amines. The phthalamic acid derived from a primary amine undergoes dehydration when heated to 145° to give a neutral A -substituted 3-nitrophthalimide. The phthalamic acid from a secondary amine is stable to heat and is, of course, soluble in alkali. The reagent therefore provides a method for distinguishing and separating a mixture of primary and secondary amines. 

The quinaldine is separated from any unreacted aniline and from the alkyl-anilines by treatment with acetic anhydride, basified with sodium carbonate and steam distilled. Only the primary and secondary amines are acetylated the acetylated amines are now much less volatile so that separation from the steam-volatile quinaldine (a tertiary amine) is facile. 

Benzenesulphonyl chloride reacts with primary and secondary, but not with tertiary, amines to yield substituted sulphonamides (for full discussion, see Section IV,100,3). The substituted sulphonamide formed from a primary amine dissolves in the alkaline medium, whilst that produced from a secondary amine is insoluble in alkali tertiary amines do not react. Upon acidifying the solution produced with a primary amine, the substituted sulphonamide is precipitated. The reactions form the basis of the Hinsberg procedure for the separation of amines see Section IV,100,(viii) for details. Feebly basic amines, such as o-nitroaniline, react slowly in the presence of allcali in such cases it is best to carry out the reaction in pyridine solution see Section IV,100,3. ... 

High molecular weight primary, secondary, and tertiary amines can be employed as extractants for zirconium and hafnium in hydrochloric acid (49—51). With similar aqueous-phase conditions, the selectivity is in the order tertiary > secondary > primary amines. The addition of small amounts of nitric acid increases the separation of zirconium and hafnium but decreases the zirconium yield. Good extraction of zirconium and hafnium from ca 1 Af sulfuric acid has been effected with tertiary amines (52—54), with separation factors of 10 or more. A system of this type, using trioctylarnine in kerosene as the organic solvent, is used by Nippon Mining of Japan in the production of zirconium (55). 

In this case the final dehydrogenation of 1,2-dihydroquinaldine to quinaldine is effected by anils formed by the condensation of aniline with either acetaldehyde or crotonaldehyde during the course of the reaction. This yields secondary amines as by-products these together with excess aniline are separated from the quinaldine by acetylation of the reaction mixture. The acetylated primary and secondary amines thus formed are less steam volatile than quinaldine which forms the basis of the isolation of the latter. 

Using this protocol, primary aliphatic amines, secondary aliphatic amines, and diamines could be converted into the corresponding urea derivatives in moderate yields. Additionally, catalytic efficiency of cations derived from various bases decreases in the order of > diamines > primary amines > secondary amines > aniline, probably being due to the steric effect and basicity. The catalyst could also be recovered after a simple separation procedure, and reused over five times with retention of high activity. This process presented here could show much potential application in industry due to its simplicity and ease of catalyst recycling. 

Secondary A-nitrosoamines are stable under the reaction conditions because they do not have the N—H proton needed for the tautomerism (shown in Mechanism 19-6 with a primary amine) to form a diazonium ion. The secondary A-nitrosoamine usually separates from the reaction mixture as an oily liquid. 

The parent alcohol is conveniently liberated from 3 on treatment with gaseous ammonia3,96 or a primary or secondary amine.13 Since the resulting 3-aminobenz[sparingly soluble in most solvents, separation from the alcohol offers no problem. 

The organic amine extractants are the most commonly used anion exchangers. Secondary amines have been used to recover uranium from leach liquors (GlO) secondary and tertiary amines to recover molybdenum from uranium mill circuits (L13) a primary amine, diethylenetriamine-penta-acetic acid (DTPA) to extract cerium group lanthanides (B6) tri-,V-butylamine-3-methyl-2-butanonc to separate yttrium and rare earth nitrates (G13) tricaprylyl amine (Alamine 336) and methyltrioctyl-ammonium salt (Aliquat 336) to recover vanadium from acidic solutions (A3) and Aliquat 336 to extract vanadium from slightly acidic or alkaline leach liquor (S36). 

What do we observe when we treat an amine with benzenesulfonyl chloride and excess potassium hydroxide A primary amine yields a clear solution, from which, upon acidification, an insoluble material separates. A secondary amine yields an insoluble compound, which is unaffected by acid. A tertiary amine yields an insoluble compound (the unreacted amine itself) which dissolves upon acidification of the mixture. 

---