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Amines coupling with diazonium salts

The primary aromatic amines which will be preferentially nitrosated rather than diazotized are those which do not bear strongly electron-withdrawing substituents and are capable of coupling with diazonium salts to give azo dyes. [Pg.450]

Coupling Components With Condensed Cyclic Ammo nium Residues. Heterocyclic compounds in which the condensed benzene ring is substituted by a hydroxyl or an amino group can be coupled with diazonium compounds and may also be quatemized, either prior or subsequent to the coupling reaction, to yield cationic azo dyes. l,2-Dialkyl-6-nitroindazolium salts are reduced to the 6-amino compounds and then coupled with diazonium salts of aromatic amines. These dyes (e g., 21) color polyacrylonitrile in bright yellow to orange shades [64],... [Pg.235]

Aryldiazonium salts are weak electrophiles. Consequently, they undergo Ar-SE reactions via sigma complexes (azo couplings) only with the most strongly activated aromatic compounds. Only phenolates and secondary and tertiary aromatic amines react with them. Primary aromatic amines react with diazonium salts, too, but via their N atom. Thus, triazenes, that is, compounds with the structure Ar—N=N—NH—Ar are produced. Phenol ethers or nonde-protonated phenols can react with aryldiazonium salts only when the latter are especially good... [Pg.223]

Nitrogen s extra pair of electrons, which is responsible for the usual basicity of nitrogen compounds, is involved in the tt cloud, and is not available for sharing with acids. In contrast to most amines, therefore, pyrrole is an extremely weak base (ATj, -- 2.5 X 10 14). By the same token, there is a high electron density in the ring, which causes pyrrole to be extremely reactive toward electrophilic substitution it undergoes reactions like nitrosation and coupling with diazonium salts which are characteristic of only the most reactive benzene derivatives, phenols and amines. [Pg.1005]

Like other aromatic compounds, these five-membered heterocycles undergJ nitration, halogenation, sulfonation, and Friedel-Crafts acylation. They are mucji more reactive than benzene, and resemble the most reactive benzene derivatives (amines and phenols) in undergoing such reactions as the Reimer-Tiemann reaction, nitrosation, and coupling with diazonium salts. [Pg.1008]

It is a white solid (r.d. 1.28 m.p. 123-124°C b.p. 295°C) used in rubber as an antioxidant. Naphthalen-2-ol will couple with diazonium salts at the 1 -position to form red azo compounds, a reaction used in testing for the presence of primary amines (by making the diazonium salt and adding naphthalen-2-ol). [Pg.548]

Primary aromatic amines and their N-mono- and N,N-dialkyl derivatives can be coupled with diazonium salts in a slightly acid medium. The reaction can be carried out using stabilized diazonium salts (which do not contain free nitrous acid), for example, with p-nitrobenzenediazonium fluoroborate (17) or with a salt with 1-naphthalenesulfonate. The reaction takes place in dilute acetic acid in the presence of sodium acetate. Recently, 4-azo-benzenediazonium fluoroborate was proposed as the reagent, and dimethyl sulfoxide or dimethylformamide (18, 19) as the reaction medium in which intensely colored di-cations of bis-azo dyes can be formed. [Pg.324]

Coupling reactions with diazonium salts to yield intensely colored azo derivatives have often been used for the detection of phenols, primary aromatic amines and electron-rich heterocyclics. [Pg.55]

The spacer arm length between the hapten and the carrier is in the range of 6 to 8 A, which should eliminate any steric interference with carrier side chains. According to the protocol described by Schultz the haptens were coupled to BSA and KLH via A-(3-dimethylaminopropyl)-A -ethylcarbodiimide or the N-hydroxysuccinimide ester at pH 5.5 in water. Other coupling strategies include substitution with diazonium salts and reductive amination. The ratio of hapten-carrier range between 8 and 15 haptens per carrier. [Pg.308]

Azo couplings of diazonium salts with primary or secondary amines give triazenes which are normally hard to get in pure form. It is, however, quite easy to get triazenes with aliphatic or aromatic amines if solid-state techniques are applied that give rise to pure products in quantitative yield [98-100]. The di-methyltriazenes 309 have been quantitatively obtained by very cautious addition of gaseous dimethylamine (exothermic ) [98] (Scheme 47). Extreme care has to be taken for safety reasons ... [Pg.150]

Perhaps the best-known method of preparing aromatic azo compounds involves the coupling of diazonium salts with sufficiently reactive aromatic compounds such as phenols, aromatic amines, phenyl ethers, the related naphthalene compounds, and even sufficiently reactive aromatic hydrocarbons. Generally, the coupling must be carried out in media which are neutral or slightly basic or which are buffered in the appropriate pH range. The reaction may also be carried out in nonaqueous media. While some primary and secondary aromatic amines initially form an A-azoamine, which may rearrange to the more usual amino-C-azo compound, tertiary amines couple in a normal manner. [Pg.399]

Generally the coupling of diazonium salt is carried out under neutral to slightly alkaline conditions. In coupling with amines or phenols, it has been demonstrated that the active species are the diazonium cation, the free amine,... [Pg.401]

A method frequently used to determine aromatic amines in water-soluble dyes involves their extraction with chloroform, followed by diazotization of amines and coupling of diazonium salts with a reagent R-salt (disodium-3-hydroxy-naphthalene-2,7-disulfonate) or pyrazolone T (4,5-dihydro-5-oxo-l-(4-sulfophenyl-)l/7-pyrazole-3-carboxylic acid). The separated products are detected by UV-VIS spectrophotometry or fluorescence (210-212). [Pg.902]

The coupling of diazonium salts with aromatic phenols and amines yields azo compounds, which are of tremendous importance to the dye industry. [Pg.767]

Problem 23.20 (a) Coupling of diazonium salts with primary or secondary aromatic amines (but not with tertiary aromatic amines) is complicated by a side reaction that yields an isomer of the azo compound. Judging from the reaction of secondary aromatic amines with nitrous acid (S. 23.10), suggest a possible structure for this by-product. [Pg.774]

The diazonium salt is readily prepared from the aminophenyl group, but does not result from treatment of an aliphatic amine (such as the APTES-derivatized surface) with nitrous acid. The activated surface is now ready for enzyme coupling, since diazonium salts are very reactive toward protein tyrosine residues (Eq. 4.4) ... [Pg.64]

Amino-3-pyrazolin-5-ones (4-imino-3-pyrazolidinones) react with nitrous acid as do ordinary aromatic amines to form diazonium salts.426,984,1353 These then couple readily with aromatic amines,1017,1018,1060 phenols992,1323 and aliphatic compounds having active hydrogen atoms,428,1017 such as acetoacetic esters. The products are 4-azo-3-pyrazolin-5-ones (eq. 200). The diazonium salts also couple... [Pg.97]

Reduction of azo compounds to amines, with fission of the N=N double bond, assumes practical importance because so many azo compounds are readily accessible, even on an industrial scale, by coupling of diazonium salts with reactive molecules. In this way a large number of primary amines can be obtained free from isomers, which is not always easy to achieve by other... [Pg.568]

A related process that involves diazonium salts is the Pschorr reaction, hich also couples aryl diazo-nium compounds to other aromatic rings. This diazonium salt coupling can he done under acidic conditions, but addition of copper powder usually promotes the radical process. Aryl amines generate aryl diazonium salts upon treatment with nitrous acid.l An example is the reaction of 233 to give an aryl diazonium salt, which cyclized in the presence of copper to give thaliporphine (234) in 43% yield. Kupchan called this transformation an improved Pschorr reaction. 68... [Pg.1185]

The discovery of stable alkenediazonium salts by Bott initiated some investigations on the reactivity of these compounds, e.g., with the hexachloroantimonate of the 2,2-diethoxyethene-l-diazonium ion (9.100). Saalfrank and Ackermann (1981a, 1981 b) reported that 9.100 reacts with primary amines to give l/f-l,2,3-triazoles. This process might be the result of an initial A-azo-coupling reaction with the amine (characteristic of diazonium salts) with subsequent cyclization of the resulting triazene, or result from attack of the amine at the C()ff)-atom with formation of a diazoalkane that cyclizes (9-45). [Pg.415]

In acid solution, nitrite ions and aromatic amines together form diazonium salts, which for their part couple with aromatic amines to form intensively... [Pg.226]

Perhaps the best-known method of preparing aromatic azo compounds involves the coupling of diazonium salts with sufficiently reactive aromatic compounds such as phenols, aromatic amines, phenyl... [Pg.243]

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. [Pg.49]


See other pages where Amines coupling with diazonium salts is mentioned: [Pg.403]    [Pg.23]    [Pg.472]    [Pg.445]    [Pg.180]    [Pg.131]    [Pg.62]    [Pg.131]    [Pg.533]    [Pg.170]    [Pg.61]    [Pg.131]    [Pg.88]    [Pg.61]    [Pg.581]    [Pg.588]    [Pg.889]    [Pg.413]    [Pg.450]    [Pg.200]   
See also in sourсe #XX -- [ Pg.772 , Pg.773 ]

See also in sourсe #XX -- [ Pg.772 , Pg.773 ]




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Amines Diazonium salts

Amines amine salts

Amines coupling

Amines coupling with diazonium

Amines salts

Coupling with diazonium salts

Coupling with diazoniums

Diazonium coupling

Diazonium salts

Salt Coupling

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