RU2365578C1 - Method of obtaining 3, 4'-diamino-4-r-benzhydrols - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining 3,4'-diamino-4-R-benzhydrols of general formula

. Where R₁=Cl (1); R₁=Br (2); R₁=

(3), which are used as semi- products in synthesis of nitrogen dyes, consisting in simultaneous reduction of nitro- and carbonyl groups of respective dinitrobenzophenons of general formula

. Where: R₁=Cl; R₁=Br;

, reduction system Zn-NaBH₄ in alcohol with mole substratum ratio: zinc: sodium tetrahydroborate equals 1:6:0.5.

EFFECT: reduction of synthesis cost, reduction of time and temperature of process carrying out, increase of target product output.

1 cl, 2 tbl, 3 ex

Description

The invention relates to a method for the synthesis of aromatic diamino compounds, in particular to the production of 3,4'-diamino-4-R-benzhydrols of the general formula

where R ₁ = Cl (1); R ₁ = Br (2); R ₁ =

which were used as intermediates in the synthesis of azo dyes. The claimed compounds include:

3,4'-diamino-4-chlorobenzhydrol (1):

3,4'-diamino-4-bromobenzhydrol (2):

3,4'-diamino-4-phenoxybenzhydrol (3):

A known method for producing 2,5-dimethoxy-3'-aminobenzhydrol, based on a one-step reduction of the nitro and carbonyl groups of the corresponding benzophenone, which consists in the catalytic hydrogenation of the substrate using 10% Pd / C as a catalyst. The process is carried out at a hydrogen pressure of 100 kg / cm ² , in ethyl alcohol, at a temperature of 130 ° C, for 8 hours. The product yield is 53%. (Pat. 5026634, USA, 1991, Michio Ono, Hiroyuki Hirai, Nobutaka Onki, Kouichi Hanaki, Koki Nakamura).

The disadvantages of the known method for the synthesis of substituted aminobenzhydrols are the use of expensive palladium, high temperature and pressure, the duration of the process, as well as the low yield of the target compound.

The purpose of the invention is to reduce the cost of synthesis, reduce the time and temperature of the process, increase the yields of target products.

This goal is achieved by the fact that as a reducing agent uses a cheaper reagent system of zinc-tetrahydride borate sodium at a temperature of 60 ° C for 2 hours and a molar ratio of substrate: zinc:

sodium tetrahydride borate equal to 1: 6: 0.5, which allows to reduce the reaction temperature from 130 ° C to 60 ° C and reduce the process time from 8 hours to 2 hours, while the yields of the target compounds are 94.0-97.8%.

The structure and purity of the target aminobenzhydrols were analyzed by PMR, Mass spectroscopy, determination of the melting temperature and elemental composition.

The invention is illustrated by the following examples.

Example 1. 3,4'-diamino-4-chlorobenzhydrol (1)

To a suspension of 1 g (1 mol) of 3,4'-dinitro-4-chlorobenzophenone in 20 ml of ethyl alcohol at a temperature of 20 ° C add 1.27 g (6 mol) of Zn and 0.06 g (0.5 mol) of NaBH ₄ and carry out the process for 2 hours at a temperature of 60 ° C. The reaction mixture is filtered off from Zn oxide and the filtrate is treated with a 0.1 mol / L HCl solution to pH = 7. The precipitate formed is filtered off and washed with 10 ml of ethyl alcohol. Obtain 0.78 g (96% of theory) of 3,4'-diamino-4-chlorobenzhydrol - white powder, so pl. 125-128 ° C.

Found,%: C 62.81; H 5.19; N 11.28

Calculated,%: C 62.78; H 5.26; N 11.26

¹ H PMR (DMSO-d6) δ, ppm: 7.06 (d, 1H, H ⁵ , J = 7.0), 6.94 (d, 2H, H ^{2 '} , H ^6' , J = 5.0), 6.79 (s, 1H , H ² ), 6.47 (m, 3H, H ^{3 '} , H ^5' , H ⁶ ), 5.45 (s, 1H, CH), 5.35 (s, 1H, OH), 5.20 (s, 2H, NH ₂ ) 4.91 (s, 2H, NH ₂ ).

Examples 2-3. Other 3,4'-diamino-4-R-benzhydrols are prepared analogously to example 1.

Physico-chemical characteristics of 3,4'-diamino-4-R-benzhydrols are shown in tables 1 and 2.

Table 1 Connection No. Mp. ° C Exit, % Found Gross formula Calculated FROM N N FROM N N one 125-128 96.0 62.81 5.19 11.28 C ₁₃ H ₁₃ ClN ₂ O 62.78 5.26 11.26 2 122-124 97.8 53.29 4.41 9.50 C ₁₃ H ₁₃ BrN ₂ O 53.26 4.46 9.55 3 92-94 94.0 74.37 5.88 9.10 C ₁₉ H ₁₈ N ₂ O ₂ 74.40 5.91 9.14

table 2 No. ¹ N PMR (DMSO-d6) δ, ppm: one 7.06 (d, 1H, H ⁵ , J = 7.0), 6.94 (d, 2H, H ^{2 '} , H ^6' , J = 5.0), 6.79 (s, 1H, H ² ), 6.47 (m, 3H, H ^{3 '} , H ^5' , H ⁶ ), 5.45 (s, 1H, OH), 5.35 (s, 1H, OH), 5.20 (s, 2H, NH ₂ ), 4.91 (s, 2H, NH ₂ ). 2 7.20 (d, 1H, H ⁵ , J = 7.0), 6.95 (d, 2H, H ^{2 '} , H ^6' , J = 8.0), 6.80 (d, 1H, H ² , J = 1.0), 6.49 (d , 2H, H ^{3 '} , H ^5' , J = 10.0), 6.41 (dd, 1H, H ⁶ , J = 7.0, J = 1.0), 5.49 (s, 1H, CH), 5.35 (s, 1H, OH ), 5.20 (s, 2H, NH ₂ ), 4.92 (s, 2H, NH ₂ ). 3 7.32 (m, 2H, H ⁽³⁾ H ⁽⁵⁾ ), 7.03 (m, 1H, H ⁽⁴⁾ ), 6.99 (d, 2H, H ^{2 '} , H ^6' , J = 7.0), 6.86 (d , 2H, H ^{3 '} , H ^5' , J = 6.0), 6.80 (d, 1H, H ² , J = 1.0), 6.69 (d, 1H,
H ⁵ , J = 7.0), 6.54 (dd, 1H, H ⁶ , J = 6.0, J = 1.0), 6.52 (d, 2H, H ⁽²⁾ , H ⁽⁶⁾ , J = 7.0), 5.42 (s , 1H, CH), 5.39 (s, 1H, OH), 4.95 (s, 2H, NH ₂ ), 4.84 (s, 2H, NH ₂ ).

Example 4. Obtaining azo dyes based on 3,4'-diamino-4-R-benzhydrols,

where R = Cl, Br,

These diamines are diazotized under standard conditions under the influence of sodium nitrite in a hydrochloric acid medium. The resulting diazo compounds proved to be active diazo compounds in the azo coupling reaction with aromatic hydroxy compounds of the benzene, naphthalene and heterocyclic series. Based on them, bisazo dyes have been synthesized, which have increased resistance to light, dry and wet friction, washing and sweat, of the general formula:

,

,

,

where R1 =

,

,

,

Claims (1)

The method of obtaining 3,4'-diamino-4-R-benzhydrols of the General formula

where R ₁ = Cl (1); R ₁ = Br (2); R ₁ =

consisting in the simultaneous reduction of the nitro and carbonyl groups of the corresponding dinitrobenzophenones of the general formula

where R ₁ = Cl; R ₁ = Br; R ₁ =

,
the reducing system of Zn-NaBH ₄ in alcohol at a molar ratio of substrate: zinc: sodium tetrahydride borate equal to 1: 6: 0.5.