N of amines

Few examples of N-amination of azines have been reported. The use of such reagents as 0-mesitylenesulfonylhydroxylamine has led to the direct synthesis of /V-aminopyridazinium, -pyrimidinium, and -pyrazinium salts (80CPB2676), and 1-aminobarbituric acids (72CPB1814), while 0-(2,4-dinitrophenyl)hydroxylamine was a useful amino-transfer reagent in the direct synthesis of 1 -amino-6-methylthio-1,2,4-triazin-4( 17/)-ones from 2-methylthio-1,2,4-triazin-5( 1H)-ones (82JHC1583). 

The scope of direct amination reactions is not too great in comparison with all other methods for synthesizing simple N-aminoimidazoles. Probably the first specific example of N-amination of imidazoles was the synthesis of l-tosylamino-2,4,5-triphenylimidazole on treatment of the lophine anion with tosylazide [Eq. (9)] (72BCJ306). However, the yield of 35 was small because of the side formation of 2,4,6-triphenyl-l,3,5-triazine and diphenyl acetylene. 

SchifT s bases A -Arylimides, Ar-N = CR2, prepared by reaction of aromatic amines with aliphatic or aromatic aldehydes and ketones. They are crystalline, weakly basic compounds which give hydrochlorides in non-aqueous solvents. With dilute aqueous acids the parent amine and carbonyl compounds are regenerated. Reduction with sodium and alcohol gives... 

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

The addition of N-bromosuccinimide (1.1equiv) to a dichlo-romethane solution containing the alkene (1 equiv) and cyana-mide (4 equiv). The solution was maintained at room temperature (3 days) and then washed with water, dried, and concentrated in vacuo. Treatment of the bromocyanamide [intermediate] with 1% palladium on charcoal in methanol (1h) led to reduction of the for-madine. Addition of base to the reaction mixture (50% aqueous KOH, reflux 6h) followed by extraction with ether gave monoamine. (Yield is 48-64% final amine from alkenes analogous to safrole)... 

Progress has been made toward enantioselective and highly regioselective Michael type alkylations of 2-cyclohexen-l -one using alkylcuprates with chiral auxiliary ligands, e. g., anions of either enantiomer of N-[2-(dimethylamino)ethyl]ephedrine (E. J. Corey, 1986), of (S)-2-(methoxymethyl)pyrrolidine (from L-proline R. K. EHeter, 1987) or of chiramt (= (R,R)-N-(l-phenylethyl)-7-[(l-phenylethyl)iinino]-l,3,5-cycloheptatrien-l-amine, a chiral aminotro-ponimine G. M. Villacorta, 1988). Enantioselectivities of up to 95% have been reported. 

Butler recently reviewed the diazotization of heterocyclic amines (317). Reactions with nitrous acid yield in most cases N-exocyclic compounds. Since tertiary amines are usually regarded as inen to nitrosation, this... 

Some recent general reviews deal with the mechanism of N-nitrosation in aqueous solution (345), the nitrosation of secondary amines (346). the effect of solvent acidity On diazotization (347) and the reactivity of diazonium salts (1691). Therefore, a complete rationalization of the reactivity of amino azaaromatics would be timelv. 

Aminoalkylation of N-[pyridyl-(2)]thiazolyl-(2)-amine yields the C-5-substituted compound (208) (Scheme 131) (132. 382. 383). 

Secondary and tertiary amines are named as N substituted derivatives of primary amines The parent primary amine is taken to be the one with the longest carbon chain The prefix N is added as a locant to identify substituents on the ammo nitrogen as needed... 

N Nitroso amine (Section 22 15) A compound of the type R2N—N=0 R may be alkyl or aryl groups which may be the same or different N Nitroso amines are formed by ni trosation of secondary amines... 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

Preparation from Amines. The most common method of preparing isocyanates, even on a commercial scale, involves the reaction of phosgene [75-44-5] and aromatic or aUphatic amine precursors. The initial reaction step, the formation of N-substituted carbamoyl chloride (1), is highly exothermic and is succeeded by hydrogen chloride elimination which takes place at elevated temperatures. 

For methylene diphenyl diisocyanate (MDI), the initial reaction involves the condensation of aniline [62-53-3] (21) with formaldehyde [50-00-0] to yield a mixture of oligomeric amines (22, where n = 1, 2, 3...). For toluene diisocyanate, amine monomers are prepared by the nitration (qv) of toluene [108-88-3] and subsequent hydrogenation (see Amines byreduction). These materials are converted to the isocyanate, in the majority of the commercial aromatic isocyanate phosgenation processes, using a two-step approach. 

The functional group ia collectors for nonsulfide minerals is characterized by the presence of either a N (amines) or an O (carboxyUc acids, sulfonates, etc) as the donor atoms. In addition to these, straight hydrocarbons, such as fuel oil, diesel, kerosene, etc, are also used extensively either as auxiUary or secondary collectors, or as primary collectors for coal and molybdenite flotation. The chain length of the hydrocarbon group is generally short (2—8 C) for the sulfide collectors, and long (10—20 C) for nonsulfide collectors, because sulfides are generally more hydrophobic than most nonsulfide minerals (10). 

Obsolete uses of urea peroxohydrate, as a convenient source of aqueous hydrogen peroxide, include the chemical deburring of metals, as a topical disinfectant and mouth wash, and as a hairdresser s bleach. In the 1990s the compound has been studied as a laboratory oxidant in organic chemistry (99,100). It effects epoxidation, the Baeyer-Villiger reaction, oxidation of aromatic amines to nitro compounds, and the conversion of sodium and nitrogen compounds to S—O and N—O compounds. 

The N—O bond distances, found to be 0.133 to 0.139 nm for trimethyl amine oxide (1), are somewhat shorter than the single N—C bond distance of 0.147 nm ia methylamine. The N—C bond distance of 0.154 nm ia trimethyl amine oxide approaches that of the C—C bond. This is ia agreement with the respective absorptions ia the iafrared region valence vibrations of N—O bonds of aUphatic amine oxides are found between 970 920 cm (2). 

When additional substituents ate bonded to other ahcycHc carbons, geometric isomers result. Table 2 fists primary (1°), secondary (2°), and tertiary (3°) amine derivatives of cyclohexane and includes CAS Registry Numbers for cis and trans isomers of the 2-, 3-, and 4-methylcyclohexylamines in addition to identification of the isomer mixtures usually sold commercially. For the 1,2- and 1,3-isomers, the racemic mixture of optical isomers is specified ultimate identification by CAS Registry Number is fisted for the (+) and (—) enantiomers of /n t-2-methylcyclohexylamine. The 1,4-isomer has a plane of symmetry and hence no chiral centers and no stereoisomers. The methylcyclohexylamine geometric isomers have different physical properties and are interconvertible by dehydrogenation—hydrogenation through the imine. 

A)Ai-dicyclohexyl-2-benzotliiazolesulfenamide (42) [4979-32-2], The cyclohexylamine derivative is preferred over /n/ butylamine [75-64-9] and morpholine sulfenamide analogues because of lower amine volatility and less nitrosamine risk respectively. 

Nuclear Magnetic Resonance. The nmr spectmm of aromatic amines shows resonance attributable to the N—H protons and the protons of any A/-alkyl substituents that are present. The N—H protons usually absorb in the 5 3.6—4.7 range. The position of the resonance peak varies with the concentration of the amine and the nature of the solvent employed. In aromatic amines, the resonance associated with N—CH protons occurs near 5 3.0, somewhat further downfield than those in the aliphatic amines. 

The amide nitrogen readily adds across the carbonyl group of an aldehyde yielding N-hydroxyalkyl-substituted pyrrohdinones (68), eg, A/-methylol-2-pyrrohdinone [15438-71-8] (34). In the presence of secondary amines or alcohols, the hydroxyl groups are replaced (69), eg, if diethylamine is present the product is A/-diethylaminomethyl-2-pyrrohdinone [66297-50-5] (35). 

Dyes. Sodium nitrite is a convenient source of nitrous acid in the nitrosation and diatozation of aromatic amines. When primary aromatic amines react with nitrous acid, the intermediate diamine salts are produced which, on coupling to amines, phenols, naphthols, and other compounds, form the important azo dyes (qv). The color center of the dye or pigment is the -N=N- group and attached groups modify the color. Many dyes and pigments (qv) have been manufactured with shades of the entire color spectmm. 

Isoprene (2-methyl-1,3-butadiene) can be telomerized in diethylamine with / -butyUithium as the catalyst to a mixture of A/,N-diethylneryl- and geranylamines. Oxidation of the amines with hydrogen peroxide gives the amine oxides, which, by the Meisenheimer rearrangement and subsequent pyrolysis, produce linalool in an overall yield of about 70% (127—129). 

Fig. 4. (a) Yam resistance in n-cm vs amount of antistatic agent on the yam. The agent is the ethyl sulfate salt of an amine, (b) Resistance vs amount of nonionic, hygroscopic agent on the yam. Dotted lines are calculated from the specific resistance of the dry bulk solution soHd lines are experimental yam... 

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