RU2155782C2 - Method of preparing azo dyes - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: method comprises combination of azo component, which is product of reaction of 1-R-2,4 and 1-R-3,5- dinitrobenzenes with potassium tetrahydroborate, with diazo component which is 4-nitro tetrafluoroborate and 4- N,N-dimethylaminophenyl diazonium. EFFECT: new method of preparing nitroazo benzenes containing nitro group in azo component. 2 cl, 4 ex, 1 tbl

Description

 The invention relates to the field of organic chemistry, in particular to a method for producing azo dyes containing a nitro group in the azo component.

где R¹=H, CH₃, Cl, Br, OCH₃, OCH₂CH₂Cl; R²=H, CN, COOCH₃;
R³= NO₂, N(CH₃)₂, сочетанием соответствующих азосоставляющих с соответствующими диазосоставляющими (К. Ренкатараман. Химия синтетических красителей. - Л., Химия, 1975, том 3, раздел "Дисперсные красители"). Интерес к подобным продуктам обусловлен прежде всего возможностью восстановления нитрогруппы в аминогруппу, что позволяет использовать образовавшийся азокраситель в качестве диазокомпоненты непосредственно на волокне или модифицировать его молекулу замещением аминогруппы по реакциям Зандмейера, Шимана и т. п. Поскольку основной реакцией получения азокрасителей остается реакция азосочетания, то все известные азокрасители обычно содержат нитрогруппу в ядре диазокомпоненты, что, очевидно, обусловлено невозможностью провести азосочетание с неактивированными к электрофильной атаке азокомпонентами, содержащими акцепторные нитрогруппы. Как было показано ранее (Алифанова Е.Н. и др. ЖОрХ, 1993, том 29, вып.7, с. 1412-1418), восстановительная активация нитросоединений путем перевода в анионные δ-комплексы позволяет с успехом использовать их в реакции азосочетания в качестве азосоставляющей. Авторы использовали аддукты нитробензолов с ацетонид-ионом (комплексы Яновского).A significant number of azo dyes containing a nitro group in the azo component of the formula are known:

where R ¹ = H, CH ₃ , Cl, Br, OCH ₃ , OCH ₂ CH ₂ Cl; R ² = H, CN, COOCH ₃ ;
R ³ = NO ₂ , N (CH ₃ ) ₂ , by combining the corresponding azo components with the corresponding diazo components (K. Renkataraman. Chemistry of synthetic dyes. - L., Chemistry, 1975, Volume 3, section "Disperse dyes"). Interest in such products is primarily due to the possibility of reducing the nitro group to an amino group, which allows one to use the resulting azo dye as a diazocomponent directly on the fiber or to modify its molecule by substituting the amino group for Zandmeyer, Shiman, etc. Since the azo coupling reaction remains the main reaction to obtain azo dyes, all known azo dyes usually contain a nitro group in the core of the diazocomponent, which is obviously due to the inability to conduct azo tanie with non-activated to electrophilic attack azokomponentami containing nitro acceptor. As was shown earlier (Alifanova E.N. et al. ZhORKh, 1993, volume 29, issue 7, pp. 1412-1418), the reductive activation of nitro compounds by conversion to anionic δ-complexes allows their successful use in the azo coupling reaction in as azo component. The authors used adducts of nitrobenzenes with an acetonide ion (Yanovsky complexes).

где R¹=H, CH₃, Cl, Br, OCH₃, OCH₂CH₂Cl;
R²=H, CN, COOCH₃; R³=NO₂, N(CH₃)₂.The aim of the present invention was to develop a method for the synthesis of azo dyes containing nitro groups in the core of azo components, of the formula:

where R ¹ = H, CH ₃ , Cl, Br, OCH ₃ , OCH ₂ CH ₂ Cl;
R ² = H, CN, COOCH ₃ ; R ³ = NO ₂ , N (CH ₃ ) ₂ .

где R¹ и R² имеют вышеуказанные значения, с тетрагидроборатом калия.This goal is achieved by using, as the azo component of the interaction product of 1-R-2,4- and 1-R-3,5-dinitrobenzenes - dinitrobenzene of the formula:

where R ¹ and R ² have the above meanings, with potassium tetrahydroborate.

R¹=H, CH₃,Cl, Br, OCH₃, OCH₂CH₂Cl;R²=H, CN, COOCH₃; R³= NO₂, N(CH₃)
При использовании 1-R-2,4-динитробензолов образуется смесь изомерных нитроазобензолов. В качестве диазокомпоненты применяются тетрафторбораты 4-нитро- и 4-N, N-диметиламинобензолдиазония. Таким образом, данный метод позволяет непосредственно вводить арилазогруппу в электронодефицитные ароматические системы, в частности нитроарены, и является новым способом получения нитроазобензолов.The anionic hydride adducts of nitro compounds formed in this case differ from the latter in increased reactivity to electrophilic agents due to the presence of a negative charge. The formation of azo compounds occurs as a result of the replacement of one nitro group in the derivatives of m-dinitrobenzene with an arylazo group (scheme):

R ¹ = H, CH ₃ , Cl, Br, OCH ₃ , OCH ₂ CH ₂ Cl; R ² = H, CN, COOCH ₃ ; R ³ = NO ₂ , N (CH ₃ )
When using 1-R-2,4-dinitrobenzenes, a mixture of isomeric nitroazobenzenes is formed. 4-nitro- and 4-N, N-dimethylaminobenzenediazonium tetrafluoroborates are used as diazocomponents. Thus, this method allows you to directly enter an arylazo group into electron-deficient aromatic systems, in particular nitroarenes, and is a new way to obtain nitroazobenzenes.

The essence of the method is as follows. To a solution of the nitro compound in dimethyl sulfoxide (DMSO) with stirring and cooling to 0-3 ^o C add a solution of an equimolar amount of KVN ₄ in methanol. The reaction mixture was kept at the indicated temperature for 40 minutes, after which a solution of the corresponding benzo-diazonium tetrafluoroborate in DMSO was added. After 30 minutes, the resulting mixture was poured into excess water and extracted with diethyl ether. The ether extract was dried over CaCl ₂ , evaporated and the residue was poured into excess pentane. The precipitate formed is filtered off, the filtrate is evaporated, and the residue is recrystallized from ethanol. The essence of the invention is illustrated by the following examples.

Example 1,2-bromo-4,4'-dinitroazobenzene
To a solution of 5 mmol (1.24 g) of 2,4-dinitrobromobenzene in 20 ml of DMSO at a temperature of 0-3 ^° C., 5 mmol (0.27 g) of KVN ₄ in 5 ml of methanol is added. The reaction mixture was stirred vigorously for 40 minutes, after which 5 mmol (1.19 g) of n-nitrobenzenediazonium tetrafluoroborate was added. After 30 minutes, the resulting mixture was poured into a 10-fold excess of water (200 ml) and extracted with diethyl ether (3x50 ml). The ether extract was dried with CaCl ₂ , evaporated to 10 ml and poured into pentane (100 ml). Precipitated by-products are filtered off, the filtrate is evaporated, the residue is recrystallized from ethanol.

Example 2. 2-methyl-4'-N, N-dimethylamino-4-nitroazobenzene
To a solution of 5 mmol (0.91 g) of 2,4-dinitrotoluene in 20 ml of DMSO at a temperature of 0-3 ^o C add 5 mmol (0.27 g) KVN ₄ in 5 ml of methanol. The reaction mixture was stirred vigorously for 40 minutes, after which 5 mmol (1.15 g) of nN, N-dimethylaminobenzenediazonium tetrafluoroborate was added. After 30 minutes, the resulting mixture was poured into a 10-fold excess of water (200 ml), the precipitate was filtered off and dried. Purification of the product is carried out by column chromatography (silica gel, eluent-p-xylene).

Example 3. 3- (nN, N-dimethylaminophenylazo) -5-nitrobenzoic acid methyl ester
To a solution of 5 mmol (1.13 g) of methyl 3,5-dinitrobenzoic acid methyl ester in 20 ml of DMSO at a temperature of 0-3 ^° C., 5 mmol (0.27 g) of KBH ₄ in 5 ml of methanol is added. The reaction mixture was stirred vigorously for 40 minutes, after which 5 mmol (1.15 g) of nN, N-dimethylaminobenzenediazonium tetrafluoroborate was added. After 30 minutes, the resulting mixture was poured into a 10-fold excess of water (200 ml), the precipitate was filtered off and dried. Purification of the product is carried out by column chromatography (silica gel, eluent-p-xylene).

Example 4. 3,4'-dinitro-5-cyanoazobenzene
To a solution of 5 mmol (0.97 g) of 3,5-dinitrocyanobenzene in 20 ml of DMSO at a temperature of 0-3 ^° C., 5 mmol (0.27 g) of KVN ₄ in 5 ml of methanol is added. The reaction mixture was stirred vigorously for 40 minutes, after which 5 mmol (1.19 g) of n-nitrobenzenediazonium tetrafluoroborate was added. After 30 minutes, the resulting mixture was poured into a 10-fold excess of water (200 ml) and extracted with diethyl ether (3x50 ml). The ether extract was dried with CaCl ₂ , evaporated to 10 ml and poured into pentane (100 ml). Precipitated by-products are filtered off, the filtrate is evaporated, the residue is recrystallized from ethanol.

The results of elemental analysis, the data of the IR, UV, and NMR spectra of the obtained azo compounds correspond to the structure of the obtained compounds. The output, melting points and retention factors (R _f ) are shown in the table.

 Thus, the proposed method for the synthesis of nitroazobenzenes containing a nitro group in the azo component is a new way to obtain azo compounds that can be used as azo dyes.

Claims (1)

The method of obtaining azo dyes of the formula

where R ¹ is H, CH ₃ , Cl, Br, OCH ₃ , OCH ₂ CH ₂ Cl; R ² is H, CN, COOCH ₃ ; R ³ - NO ₂ , N (CH ₃ ) ₂ ,
a combination of an azo component with a diazo component, characterized in that the product of the interaction of dinitrobenzene of the formula is used as the azo component

where R ¹ and R ² have the above meanings,
with potassium tetrahydroborate, and 4-nitro and 4-N, N-dimethylaminophenyl diazonium tetrafluoroborates as the diazocomponent.

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