Treating amine

More recently, Polish chemists have reported a synthesis of both aryl and aliphatic secondary nitramines by treating amine substrates with ethyl magnesium bromide followed by reaction with n-butyl nitrate (Equation 5.8). This method, which uses nonpolar solvents like hexane or benzene, has been used to synthesize aliphatic secondary nitramines, and At-nitro-A-methylanilines which otherwise undergo facile Bamberger rearrangement in the presence of acid. The direct nitration of At-unsubstituted arylamines usually requires the presence of an electron-withdrawing group. Reactions are retarded and yields are low for sterically hindered amines. 

Emmons and co-workers prepared a series of aliphatic secondary nitramines by treating amines with a solution of dinitrogen pentoxide in carbon tetrachloride at —30 C (Equation 5.9). The amine component needs to be in excess of two equivalents relative to the dinitrogen pentoxide if high yields of nitramine are to be attained. This is wasteful because at least half the amine remains unreacted. However, yields are high and there is no reason why the amine cannot be recovered as the nitrate salt. The method is particularly useful for the nitration of hindered secondary amines substrates such as those with branching on the a carbon. 

Organic compounds containing halogen atoms attached to the nitrogen. A large number of such compounds were prepd by treating amines with1 hypochlorites. Some of these compounds are explosive ... 

Some nitramines may be prepared without treating amines with nitric acid. The classical example is the so-called E-method of cyclonite preparation in which a nitramine is formed by dehydration of a mixture of paraformaldehyde and ammonium nitrate, i.e. without using either amine or nitric acid (this will be discussed more fully on p. 109). When a nitramine is required with a non-nitrated aromatic ring which readily undergoes nitration with nitric acid, Bamberger s method [45], involving the oxidation of diazo compounds (13), may be applied. 

Carbamates have mainly been used in solid-phase synthesis as linkers and protective groups for amines (see Sections 3.6.2 and 10.1.10.1). Carbamates are generally prepared by treating amines with aryl carbonates or chloroformates, which can be prepared from alcohols and phosgene or synthetic equivalents thereof. The alternative route, in which carbamates, isocyanates, or carbamoyl chlorides are reacted with alcohols, is less widely used, but can also lead to satisfactory results on insoluble supports (Tables 14.7 and 14.8). 

Reaction CXLI. Action of Acids, Acid Anhydrides and Chlorides on Primary and Secondary Amines.—Substituted amides are usually prepared by treating amines with organic acids, or with acyl chlorides or anhydrides. When the acid is used a salt is first formed from which a molecule of water is eliminated on further heating. 

Various keto aminals were readily obtained by treating aminal II, prepared from the diamine la and methyl hydroxymethoxyacetate, with Grignard reagent (R MgX) in the presence of MgCl in good yields (Eq. 6) Successive addition of... 

Based on the ability of Pd(OAc)2 to accelerate the [2,3]-rearrangement of amine iV-oxide 114, we explored chiral palladium(ll) salts to catalyze the enantioselective rearrangement. When we treated amine iV-oxides 116 with Pd(OAc)2 and chiral phosphoramidite 118, chiral O-allylhydroxylamines 117 were isolated in 80-85% ee (Scheme 1S.28V Subsequent optimization revealed the beneficial effect of methanol and meta-chlorobenzoic acid (m-CBA) as additives, allowing the isolation of chiral nonracemic O-allylhydroxylamines 117 with greater than 90% enantioenrichment. This palladium-catalyzed enantioselective [2,31-rearrangement can tolerate a wide variety of functional groups in the amine N-oxide substrate. For example, we can synthesize chiral allylic hydrojq lamine products with reactive functional groups such as alcohols and aldehydes, which are inconpatible with many other methods for the synthesis of chiral alcohol derivatives. 

Hgure 9-45. Flow diagram of SulFerox plant used for treating amine plant tail gas. (Bu tgerelai., 1991/ ... 

The diazoamino-compounds are usually yellow in colour, and do not dissolve in acid they can usually be isolated and crystallized without decomposition. When treated with HNO2 two molecules of diazonium salt are formed. Form an azo compound when warmed with an amine and its hydrochloride, e.g. 

The diazonium salts usually decompose when warmed with water to give a phenol and nitrogen. When treated with CuCl, CuBr, KI, the diazo group is replaced by chlorine, bromine or iodine respectively (Sandmeyer reaction). A diazonium sulphate and hydroxyl-amine give an azoimide. The diazonium salt of anthranilic acid (2-aminobenzoic acid) decomposes to give benzyne. ... 

Fischer-Hepp rearrangement The nitros-amines of aromatic secondary amines when treated with hydrochloric acid give nuclear substituted nitrosoamines. Among the benzene derivatives, if the para position is free the -NO group displaces the hydrogen atom there in naphthalene derivatives it enters the 1-position ... 

Both aliphatic and aromatic nitro-compounds can be readily reduced in acid solution to the corresponding primary amine. Thus when a mixture of nitrobenzene and tin is treated with hydrochloric acid, the tin dissolves to give stannous chloride, SnCh, which in these circumstances then reacts with more acid to give stannic chloride, SnCl, and the nascent hydrogen produced from... 

The nitrosamines are insoluble in water, and the lower members are liquid at ordinary temperatures. The separation of an oily liquid when an aqueous solution of an amine salt is treated with sodium nitrite is therefore strong evidence that the amine is secondary. Diphenylnitrosoamine is selected as a preparation because it is a crystalline substance and is thus easier to manipulate on a small scale than one of the lower liquid members. For this preparation, a fairly pure (and therefore almost colourless) sample of diphenyl-amine should be used. Technical diphenylamine, which is almost black in colour, should not be employed. 

If, however, a tertiary amine has two alkyl groups and also an aryl group having the para position unsubstituted, then the action of nitrous acid is to insert the nitroso group directly into this para position. Dimethylaniline, for example, when treated with nitrous acid readily gives p-nitrosodimethyl-... 

Some less reactive tertiary amines can be mixed with an excess of methyl toluene-/)-sulphonate, m.p. 28 , and the mixture (without a solvent) heated to a much higher temperature. The mixture is allowed to cool, but before solidification occurs, it is thoroughly stirred with ether to extract unused sulphonate, and the insoluble quaternary metho-toluene-/)-sulphonate may then crystallise. If ciystallisation does not occur, dissolve this residue in ethanol and treat one portion with ethanolic picric acid (to precipitate the methopicrate) and another portion with cold concentrated ethanolic sodium iodide (to precipitate the methiodide). (M.ps. of the siilphon.ates, pp. 553 -554.)... 

By the hydrolysis of dialkyl cyanamides with dilute sulphuric acid this method gives pure secondary amines. The appropriate dialkyl cyanamide is prepared by treating sodium cyanamide (itself obtained in solution from... 

SULPHONATION OF AROMATIC AMINES If aniline is treated with excess of concentrated sulphuric acid and the resulting mixture, which contains aniline sulphate, is heated at 180° until a test portion when mixed with sodium hydroxide solution no longer liberates aniline, p-aminobenzenesulphonic acid or sulphanilic acid is formed this separates as the dihydrate upon pouring the cooled mixture into water. The reaction prohahly proceeds as follows ... 

In the preparation of bromo compounds by the Sandmeyer reaction, the amine is generally diazotised in sulphuric acid solution (or in hydrobromic acid solution), and the resulting aryldiazonium sulphate (or bromide) is treated with a solution of cuprous bromide in excess of hydrobromic acid the addition... 

Method 1. Treat 2 0 g. of the mixture of amines with 40 ml. of 10 per cent, sodium hydroxide solution and add 4 g. (3 ml.) of benzenesulphonyl chloi de (or 4 g. of p-toluenesulphonyl chloride) in small portions. Warm on a water bath to complete the reaction. Acidify the alkaline solution with dilute hydrochloric acid when the sulphonamides of the primary and secondary amines are precipitated. Filter off the solid and wash it with a little cold water the tertiary amine will be present in the filtrate. To convert any disulphOnamide that may have been formed from the primary amine into the sulphonamide, boil the solid under reflux with 2 0 g. of sodium dissolved in 40 ml. of absolute ethyl alcohol for 30 minutes. Dilute with a little water and distil off the alcohol filter off the precipitate of the sulphonamide of the secondary amine. Acidify the filtrate with dilute hydrochloric acid to precipitate the derivative of the primary amine. Recrystallise the respective derivatives from alcohol or from dilute alcohol, and identify them inter alia by a determination of the m.p. 

Treat 1 g. (1 ml.) of the amine with 4 mols of 10 per cent, sodium or potassium hydroxide solution (say, 20 ml,), and add 1 -5 mols (or 3 g. if the molecular weight is unknown) of benzenesulphonyl or p-toluenesulphonyl chloride in small portions with constant shaking. To remove the excess of acid chloride, either shake vigorously or warm gently. Acidify with dilute hydrochloric acid and filter off the sulphonamide. Recrystallise it from alcohol or dilute alcohol. 

Group II. The classes 1 to 5 are usually soluble in dilute alkali and acid. Useful information may, however, be obtained by examining the behaviour of Sails to alkaline or acidic solvents. With a salt of a water-soluble base, the characteristic odour of an amine is usually apparent when it is treated with dilute alkali likewise, the salt of a water soluble, weak acid is decomposed by dilute hydrochloric acid or by concentrated sulphuric acid. The water-soluble salt of a water-insoluble acid or base will give a precipitate of either the free acid or the free base when treated with dilute acid or dilute alkali. The salts of sulphonic acids and of quaternary bases (R4NOH) are unaflFected by dilute sodium hydroxide or hydrochloric acid. 

Acetyl chloride test (for primary and secondary amines). In a semi-micro test-tube (75 x 10 mm.) treat 0-5 ml. (or 0-5 g.) of the compound with acetyl chloride drop by drop. Note whether reaction occurs. If no solid separates, pour the contents of the tube into 3 ml. of water and neutralise the aqueous layer with solid sodium bicarbonate. Observe whether a product different from the original compound is produced. 

The following are examples of the above procedure. A mixture of diethylamine and re-butyl alcohol may be separated by adding sufficient dilute sulphuric acid to neutralise the base steam distillation will remove the alcohol. The amine can be recovered by adding sodium hydroxide to the residue and repeating the distillation. A mixture of diethyl ketone and acetic acid may be treated with sufficient dilute sodium hydroxide solution to transform the acid into sodium acetate and distilling the aqueous mixture. The ketone will pass over in the steam and the non-volatile, stable salt will remain in the flask. Acidification with dilute sulphuric acid hberates acetic acid, which can be isolated by steam distillation or by extraction. 

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