Free amine

Into a 750 ml. round-bottomed flask furnished with a reflux condenser place a solution of 34 g. (18-5 ml.) of concentrated sulphuric acid in 100 ml, of water add 33 g. of di-n-butyl cyanamide and a few fragments of porous porcelain. Reflux gently for 6 hours. Cool the resulting homogeneous solution and pour in a cold solution of 52 g. of sodium hydroxide in 95 ml. of water down the side of the flask so that most of it settles at the bottom without mixing with the solution in the flask. Connect the flask with a condenser for downward distillation and shake it to mix the two layers the free amine separates. Heat the flask when the amine with some water distils continue the distillation until no amine separates from a test portion of the distillate. Estimate the weight of water in the distillate anp add about half this amount of potassium hydroxide in the form of sticks, so that it dissolves slowly. 

With a large excess of sodium hydroxide solution, the salt complex is decomposed and the free amine is liberated ... 

The disadvantages attending the use of acetic anhydride alone are absent when the acetylation is conducted in aqueous solution according to the following procedure. The amine is dissolved in water containing one equivalent of hydrochloric acid, slightly more than one equivalent of acetic anhydride is added to the solution, followed by enough sodium acetate to neutralise the hydrochloric acid, and the mixture is shaken. The free amine which is liberated is at once acetylated. It must be pointed out that the hydrolysis of acetic anhydride at room temperature is extremely slow and that the free amine reacts much more readily with the anhydride than does the water this forms the experimental basis for the above excellent method of acetylation. 

The amines are comparatively weak bases, so that a certain amount of free amine will be produced by salt hydrolysis unless an excess of acid is present. The reaction mixture must be kept very cold during the process (which is exothermic in character), otherwise the diazonium salt may be partially converted into the corresponding hydroxy compound ... 

Method 2 (from the free amine). Dissolve 9 - 3 g. (9 1 ml.) of aniline in 10 ml. of glacial acetic acid diluted to 100 ml. contained in a 250 ml. beaker or conical flask, and add with stirring or shaking a solution of 6 5 g. of pure sodium cyanate in 50 ml. of warm water. Allow to stand for 30 minutes, then cool in ice, and allow to stand for a further 30 minutes. Filter at the pump, wash with water and dry in the steam oven. The resulting phenylurea is generally colourless and has a m.p. of 148° (i.e., is pure) the yield is 11 g. If the colour or the m.p. of the product is not quite satisfactory, recrj stallise it from boiling water (10 ml. per gram) as in Method 1. 

Hydrolysis of a sulphonamide. Mix 2 g. of the sulphonamide with 3-5 ml. of 80 per cent, sulphuric acid in a test-tube and place a thermometer in the mixture. Heat the test-tube, with frequent stirring by means of the thermometer, at 155-165° until the solid passes into solution (2-5 minutes). Allow the acid solution to cool and pour it into 25-30 ml. of water. Render the resulting solution alkaline with 20 per cent, sodium hydroxide solution in order to liberate the free amine. Two methods may be used for isolating the base. If the amine is volatile in steam, distil the alkaline solution and collect about 20 ml. of distillate extract the amine with ether, dry the ethereal solution with anhydrous potassium carbonate and distil off the solvent. If the amine is not appreciably steam-volatile, extract it from the alkaline solution with ether. The sulphonic acid (as sodium salt) in the residual solution may be identified as detailed under 13. 

Their basicity provides a means by which amines may be separated from neutral organic compounds A mixture containing an amine is dissolved m diethyl ether and shaken with dilute hydrochloric acid to convert the amine to an ammonium salt The ammonium salt being ionic dissolves m the aqueous phase which is separated from the ether layer Adding sodium hydroxide to the aqueous layer converts the ammonium salt back to the free amine which is then removed from the aqueous phase by extraction with a fresh portion of ether... 

A variation of this method involves the conversion of the amine into the amine hydrochloride prior to treatment with phosgene. This method has the advantage of producing generally cleaner products by retarding the secondary reaction of the free amine with carbamoyl chloride. 

Alkan olamines ate used in urethane coatings for glass shatter proofing (68) and have been utilized as amides, salts, or free amines in providing antifrosting, antifogging, and dirt-resistant films on glass and plastics (69—72). 

The resulting acetyl compound is usually hydrolyzed with aqueous alkaU to give the free amine. Other A/-acyl derivatives may be used, particularly for the less soluble succinyl and phthaloyl products. The use of -nitrobenzenesulfonyl chloride, followed by reduction of the nitro to an amino function, is much more expensive and is rarely used. A/-Acetylsulfanilyl chloride [121 -60-8] is obtained by the chlorosulfonation of acetanilide [103-84-4] which is the basic material for most of the sulfonamides. 

Other Accelerators. Amine isophthalate and thiazolidine thione, which are used as alternatives to thioureas for cross-linking polychloroprene (Neoprene) and other chlorine-containing polymers, are also used as accelerators. A few free amines are used as accelerators of sulfur vulcanization these have high molecular weight to minimize volatility and workplace exposure. Several amines and amine salts are used to speed up the dimercapto thiadiazole cure of chlorinated polyethylene and polyacrylates. Phosphonium salts are used as accelerators for the bisphenol cure of fluorocarbon mbbers. 

In one experiment the effect of ppd assay was correlated to scorch safety. As the ppd degrades Hberate free amine, scorch time decreases and cure rate is faster. The degradation products apparentiy serve to activate the cure, since both the induction time, and cure time, decrease with decreasing ppd assay. However, the effect on unaged properties is minimal. 

Tertiary Amine-Containing Copolymers. Copolymers based on DMAEMA (dimethylarninoethyl methacrylate) in either free amine form or quatemized with diethyl sulfate or methyl chloride have achieved commercial significance as fixatives in hair-styling formulations, especially in the weU-pubhcized "mousses" or as hair-conditioning shampoo additives. This success has occurred because the cationic charge affords substantive resins that strongly adhere to the hair (141). 

The acid—base equiUbtia are fundamental to the kinetics of azo coupling and of practical significance for azo technology. Thus it is important that coupling reactions be carried out in a medium such that the acid—base equiUbtia of the diazo and coupling components favor as much as possible the diazonium ions and the phenolate ions or the free amine, respectively. 

However, as HOX is consumed, hydrolysis is retarded because of build-up of free amine. Consumption of hypohalous acid through reaction with HX can result in formation of elemental halogen HOX + + X X2 + H2 O (1—3). The tendency for halogen formation is much greater for HOBr and... 

DETA has been produced by reaction of monoethanol amine [141-43-5] (MEA) and EDA with urea (42). In this process, MEA reacts with urea to form 2-oxa2ohdinone which then reacts with EDA to form the cycHc urea of diethylene-triamine. Hydrolysis of the ureaHberates the free amine. 

As many natural and synthetic /3-lactams bear 3-acylamino substituents, the corresponding free amines or protected forms thereof are versatile synthetic intermediates. They may be prepared in several ways, for example by deacylation of the 7-amido group in naturally occurring penicillins by enzymic or chemical means. Chemical degradation usually involves conversion of the amide to a chloroimidate followed by cleavage with aqueous alcohols (75S547 p. 560, 78T1731 p. 1753). 

Early attempts to produce cephalosporin analogs by varying the 7-acylamino substituent were frustrated because, in contrast to previous experience with penicillins, a good method for producing the necessary 7-amino compound (33a) could not be found. This problem was finally solved when it was discovered that diazotization of the a-aminoadipyl residue produces an iminolactone (33b) which can be hydrolyzed to the free amine in good yield. Subsequently an improved procedure was developed which involves silylation of the carboxyl groups followed by reaction with phosphorus pentachloride to yield iminochloride (33c)... 

The Fmoc group is cleaved under mild conditions with an amine base to afford the free amine and dibenzofulvene. The approximate half-lives for the. deprotection of Fmoc-ValOH by a variety of amine bases in DMF are as follows ... 

Alternatively, the amine may be dissolved in a suitable solvent (e.g. toluene) and dry HCl gas is passed through the solution to precipitate the amine hydrochloride. This is purified by recrystallisation firom a suitable solvent mixture (e.g. ethanol/diethyl ether). The free amine can be regenerated by adding sodium hydroxide and isolated as above. 

Tetramethylammonium chloride [75-57-0] M 109.6, m >230°(dec). Crystd from EtOH, EtOH/CHCl3, EtOH/diethyl ether, acetone/EtOH (1 1), isopropanol or water. Traces of the free amine can be removed by washing with CHCI3. 

Tri-n-octylamine [1116-76-3] M 353.7, b 164-168 /0.7mm, 365-367 /760mm, d 0.813, n 1.450, pK 10.65. It was converted to the amine hydrochloride etherate which was recrystd four times from diethyl ether at -30° (see below). Neutralisation of this salt regenerated the free amine. [Wilson and Wogman J Phys Chem 66 1552 1962.] Distd at l-2mm pressure. 

Potential ionic interactions may also be provided by the free amine groups of the arginine fragment. As a consequence, the net character of the heptapeptide will be polar, and the peptide would be classed as hydrophilic or lyophilic in nature. 

The enamines in which the protonation at the -carbon atom is not allowed due to the lack of coplanarity, or, in other words, the lack of electronic overlap, do not exhibit this characteristic absorption shift. For instance in the case of neostrychnine (134) where the overlap is not permitted since this would involve the formation of a double bond at the bridgehead, there is no appreciable difference in the C—C stretching region of the free amine and its perchlorate salt they absorb at 1666 cm and 1665 cm , respectively (70). 

Enamines in which the double-bond shift is sterically prevented afford only the ammonium salts. Their spectra in the C=C stretching vibration region does not differ greatly from that of the free amine spectrum (171). For example, neostrychnine (159) has vc c 1666 cm and its perchlorate at 1665 cm . Salts of quinuclideine (92) and the polycyclic alkaloid trimethylconkurchine have similar properties. 

This sulfonate, prepared from B0CNHCH2CH2C(CH3)2CH20H and the sulfonyl chloride (Pyr, 100% yield) is cleaved by initial BOC cleavage to release the free amine after pH adjustment to 7-8. Intramolecular displacement occurs to release the sulfonate and a pyrrolidine. ... 

Pd(Ph3P)4 and Bu3SnH convert the Alloc group to other amine derivatives when electrophiles such as (B0C)20, AcCl, TsCl, or succinic anhydride are added. Hydrolysis of the stannyl carbamate with acetic acid gives the free amine. 

The free amine can be monoacylated. Without this protection, only the bisacy-lated derivative is obtained. ... 

Acylthiomercaptobenzotriazoles, PPTS, 52-80% yield. In this case, the amide is formed rather than the free amine. 

For aryl amines the reaction mixture should be slightly acidic or neutral, in order to have a high concentration of free amine as well as arenediazonium ions. Aryl ammonium species—ArNH3+—are unreactive. The coupling of the diazonium species with aromatic amines proceeds by an analogous mechanism ... 

The reactive species for the transfer of the nitrosyl cation NO+ is not the nitrous acid 2 but rather N2O3 4 which is formed in weakly acidic solution. Other possible nitrosating agents are NOCl or H2N02 ", or even free NO+ in strong acidic solution. The initially formed N2O3 4 reacts with the free amine 1 ... 

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