Amino-group

Amino groups have been determined by acetylation with acetic anhydride in dimethylacetamide. Diethylamine was added and the excess amine was titrated potentiometrically [127]. 

Heterogeneous derivitivisation with l-fluoro-2,4-dinitrobenzene has been used to determine amino groups in polyethylene terephthalate [8]  

The polymer is treated for 4 hours at 80 °C with l-fluoro-2,4-dinitrobenzene in an ethanol hydrogen carbonate medium. After washing out the excess of reagent, the dinitrophenyl group introduced is measured spectrophotometrically at 430 nm after dissolution of the derivatised polymer in methane sulfonic acid. 

The spectrophotometric method was calibrated with the l-fluoro-2,4-dinitrobenzene derivative of the model compound N,N -bis(p-amino-phenyl) terephthalamide. 

The correctness of this procedure was confirmed using C-labelled l-fluoro-2,4 dinotrobenzene and measurement of incorporated radioactivity. 

Two indirect titration procedures have been described for the determination of amino end groups in aromatic polyamides. One method involves the reaction of the amine with salicylaldehyde to form the Schiff base. After precipitation of the polymer, the excess, unreacted aldehyde is titrated with potassium hydroxide [153]. 

Modification of the amino groups by acetylation with acetic anhydride and deamination by nitrous acid yielded derivatives which showed 

Antigen Stokes radius (nm) Number of disulfide groups reacted Percent reactivity with anti-BSA 

Antibody against the following antigen Anti-bovine serum albumin  

Primary and secondary amines are susceptible to oxidation and replacement reactions involving the N—H bonds. Within the development of peptide synthesis numerous protective groups for N—H bonds have been found (M. Bodanszky, 1976 L.A. Carpino, 1973), and we shall discuss five of the more general methods used involving the reversible formation of 

Tceoc Cbzc Z ) o II R-NH—C-O—CHj—CC13 O R-NH-C-O-CHj TceocCI CI-CO-OCH2Ph Zn/AcOH or cathodic reduction — COjt -CH2=CC12 t HBr/AcOH or H2[Pd] 

Trifluoroacetamides are more stable toward nucleophiles than the corresponding esters and are easily formed from trifluoroacetic anhydride and the amine. The trifluoroacetyl group (Tfac) is slowly cleaved by aqueous or methanolic HQ, NH3, or Ba(OH)2 solutions as well as by NaBH4 in methanol (M.L. Wolfrom, 1967). 

The /-butoxycarbonyl group (Boc, 7-box ) has been extensively used in peptide synthesis, and Boc derivatives of many amino acids are commercially available. The customary reagent for the preparation from the amine is /-butyl azidoformate in water, dioxane/water, DMSO, or DMF. The cleavage by acids of medium strength proceeds with concomitant loss of isobutene and carbon dioxide (L.A. Carpino, 19S7, 1973 see section 4.1.2.2). 

The phthaloyl (Phth) derivatives of amines, formed from amines and N-ethoxy-carbonylphthalimide (G.H.L. Nefkens, 1960), are acid-resistant imides, which can be easily deblocked by nucleophilic reagents, most conveniently by hydrazine. 

Octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine or cyclotetramethylene tetranit-ramine (HMX) with a m.p. of 291 °C, is also regarded as a heat-resistant explosive in some countries [32, 33] and its safe working limit is 225 °C. 

Salt Formation Thermal stability is enhanced by the salt formation [34] which may be illustrated by the following example [Structures (2.16) and Structure (2.17)] 

Introduction of Amino Groups The introduction of an amino (-NH2) group (in ortho position) into a benzene ring already having a nitro (-N02) group is one of the simplest and oldest approaches to enhance thermal stability of explosives [35-37]. This is evident from the study of the effect of introduction of amino groups in trinitrobenzene (TNB) [Structure (2.18)] to form monoamino-2,4,6- 

Several methods have been reported in the literature for the synthesis of TATB [24]. Considering the ease of synthesis, purity and yield of the resulting TATB, its synthesis from symmetrical trichlorobenzene (sym.-TCB) is regarded as a method of choice for scaling-up and now almost all countries follow this method for its 

The process has been successfully scaled-up to pilot plant level and the product characteristics are yield 98%, purity 95-99% and particle size 40-60 pm. At the same time, this process reduces the environmental impact of TATB production as compared with the traditional TCB Route [52]. 

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Azo-compounds can be obtained by reduction of nitro-compounds, or by oxidation of hydrazo-compounds. They are usually prepared, however, by reacting a phenol or amine with a diazonium salt. The coupling usually takes place in the position para to the hydroxyl or amino group, but if this position is occupied it goes to the ortho position, e.g. 

Yellow liquid m.p. 26" C, b.p. l37 "C/2mm. Reagent introduced by Sanger for identification of the terminal amino group of peptides with which it forms an /V-2,4-dlni-irophenyl derivative under mild conditions. 

Gattermann s reaction A variation of the Sandmeyer reaction copper powder and hydrogen halide are allowed to react with the diazonium salt solution and halogen is introduced into the aromatic nucleus in place of an amino group. 

CfiHsNjOs. Red needles m.p. 168-169°C. Soluble in dilute acids and alkalis. Prepared by reduction of picric acid with sodium hydrogen sulphide, ft is used for the preparation of azodyes, which can be after-chromed by treatment with metallic salts owing to the presence of a hydroxyl group ortho to the amino-group. 

Figure 10.3-40. The rating for the disconnection strategy carbon-heteroatom bonds is illustrated, Please focus on the nitrogen atom of the tertiary amino group. It is surrounded by three strategic bonds with different values. The low value of 9 for one ofthese bonds arises because this bond leads to a chiral center. Since its formation requires a stereospecific reaction the strategic weight of this bond has been devalued. In contrast to that, the value of the bond connecting the exocyclic rest has been increased to 85, which may be compared with its basic value as an amine bond.

This elimination of the diazonium group is therefore a very valuable reaction, as it affords almost the only method by which nitro and primary amino groups directly attached to the benzene ring can be eliminated. 

When hydrochloric acid is cautiously added to an aqueous solution containing both sodium nitrite and the sodium salt of sulphanilic acid, NaOsSCgH NH, the amino group of the latter undergoes normal diazotisation, giving the diazonium chloride (A). The latter, however, ionises in solution, giving sodium and chloride ions and the internal salt (B), which possesses two opposite charges and is therefore neutral this internal salt is stable under... 

This preparation illustrates the use of dimethyl sulphate to convert a primary amino group into the secondary monomethylamino group, without the methy-lation proceeding to the tertiary dimethylamino stage. The methylation of anthranilic acid is arrested at the monomethylamino stage by using i-i molecular equiN alents of sodium hydroxide and of dimethyl sulphate. The reactions can be considered as ... 

When a mixture of aniline, nitrobenzene, glycerol and concentrated sulphuric acid is heated, a vigorous reaction occurs with the formation of quinoline. It is probable that the sulphuric acid first dehydrates the glycerol giving acrolein or acraldehyde (A), which then condenses at its double bond with the amino group of the aniline to give acrolein-aniline (B), The latter in its enol... 

Estimation of the Number of Amino Groups in Aniline. First Method. 

If the molecular weight of the aniline is known, the number of amino groups can be calculated alternatively, if the aniline is known to be a monacidic base, its molecular weight can be calculated. If the molecular weight and the acidity of the aniline are both known, then dearly the method can be used to estimate the amount of aniline in a given sample. The method is general for many primary and secondary amines, aniline being used solely as a typical member of the former class. 

Another important method of following protein hydrolysis is that due to Van Slyke, and consists in estimating the free amino groups liberated by treatment with nitrous acid, whereby gaseous nitrogen is evolved and measured in a special apparatus. 

Crystalline derivatives of amino acids are usually produced by reaction at the amino group by treatment with appropriate reagents in alkaline solution ... 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

Mono-substitution products of primary amines cannot easUy be prepared by direct action of the appropriate reagent for example, bromination of aniline yields largely the 2 4 6-tribomo derivative and nitration results in much oxidation. If, however, the amino group is protected as in acetanilide, smooth substitution occurs. Thus with bromine, />-bromoacetanilide is the main product the small quantity of the ortlio isomeride simultaneously formed can be easily eliminated by crystallisation. Hydrolysis of p-bromoacetanilide gives/ -bromoaniline ... 

The diazonium group may be replaced by hydrogen, thus effecting the removal of the primary amino group, deamination, by the following methods ... 

Compounds containing two primary amino groups attached to a benzene ring can be prepared by the reduction of dinitro compounds and of nitroanilines, usually with tin or stannous chloride and hydrochloric acid or with iron and very dilute hydrochloric acid. / ara-diamines may also be obtained by the reduction of aromatic amino-azo compounds (e.g., p-aminodimethylanihne from methyl orange, see Section IV,78). p-Phenylenediamine may also be prepared from p-nitroacetanilide reduction with iron and acid yields p-amino-acetaniUde,.which may be hydrolysed to the diamine. 

Acetates may also be prepared by adding acetic anhydride to somewhat dilute solutions of compounds containing hydroxyl (or amino) groups in aqueous caustic alkahs. The amount of alkali used should suffice to leave the hquid shghtly basic at the end of the operation, so much ice should be added that a little remains unmelted, and the acetic anhydride should be added quickly. 

The presence of certain substituents e.g., the amino group) may markedly affect the solubibty and other properties of the sulphonic acid or carboxylic acid. Thus such sulphonic acids as the aminobenzenesul-phonic acids, pyridine- and quinoline-sulphonic acids exist in the form of inner salts or zwitter-ions that result from the interaction of the basic amino group and the acidic sulphonic acid. Sulphanilic acid, for example, is more accurately represented by formula (I) than by formula (II) ... 

Periodic acid has a selective oxidising action upon compounds having two hydroxyl groups or a hydroxyl and an amino group attached to adjacent carbon atoms and is characterised by the cleavage of the carbon - carbon bond (Malaprade reaction) ... 

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