Complexes of Amines with Some Bromonitrophenols and Their Bactericidal Properties
Abstract Generated abstract
This study examines the preparation and antibacterial activity of amine complexes with 2-bromo-4-nitrophenol and 2,6-dibromo-4-nitrophenol. Seventeen previously undescribed crystalline complexes were synthesized, characterized by composition, nitrogen analysis, melting point, solubility, and color, and then tested against Escherichia coli by a suspension method measuring active concentration and exposure time. The results indicate that bactericidal activity depends on both the amine structure and the bromonitrophenol component, with complexes of 2,6-dibromo-4-nitrophenol generally more active than those of 2-bromo-4-nitrophenol. Complex formation was found to alter activity relative to the individual components, in some cases increasing and in others reducing bactericidal action.
Full Text
AMINE COMPLEXES WITH CERTAIN BROMONITROPHENOLS AND THEIR BACTERICIDAL PROPERTIES
I. M. Bortovoi, G. L. Ryzhova, L. I. Potekhina
(Presented by Prof. B. V. Tronov, Doctor of Chemical Sciences)
Amine complexes with nitrophenols are acquiring ever greater practical importance. Thus, for example, butezine picrate has found application in medicine [1], a complex of benzylamine with 2,4-dinitro-6-methylphenol has been proposed as an insecticide [8], and compounds of trinitrophenol are widely used in organic analysis for identification by melting points [2].
The use of complex compounds as bactericides is of considerable interest; however, they have been little studied in this direction.
In the present work, some new amine complexes with 2-bromo-4-nitrophenol and 2,6-dibromo-4-nitrophenol are described, obtained with the aim of clarifying the influence of complex formation on bactericidal properties.
The complexes were synthesized by the usual method. The compounds obtained (Table 1) are crystalline substances, colored from light yellow to bright yellow.
Table 1
| No. | Complex compound | Composition | % nitrogen, found | % nitrogen, calculated |
|---|---|---|---|---|
| 1. | alpha-Naphthylamine + 2-bromo-4-nitrophenol | 1:2 | 6.51 and 6.55 | 7.25 |
| 2. | beta-Naphthylamine + 2-bromo-4-nitrophenol | 1:2 | 6.73 and 7.12 | 7.25 |
| 3. | Benzidine + 2-bromo-4-nitrophenol | 1:2 | 8.93 and 8.60 | 9.03 |
| 4. | para-Phenylenediamine + 2-bromo-4-nitrophenol | 1:2 | 9.62 and 9.77 | 10.29 |
| 5. | ortho-Anisidine + 2-bromo-4-nitrophenol | 1:1 | 7.93 and 7.80 | 8.20 |
| 6. | para-Anisidine + 2-bromo-4-nitrophenol | 1:1 | 8.02 and 7.70 | 8.20 |
| 7. | Pyridine + 2-bromo-4-nitrophenol | 1:1 | 8.98 and 9.80 | 9.43 |
| 8. | alpha-Naphthylamine + 2,6-dibromo-4-nitrophenol | 1:1 | 5.20 and 6.42 | 6.33 |
| 9. | beta-Naphthylamine + 2,6-dibromo-4-nitrophenol | 1:1 | 5.90 and 6.62 | 6.33 |
| 10. | Benzidine + 2,6-dibromo-4-nitrophenol | 1:2 | 7.60 and 7.77 | 7.19 |
| 11. | ortho-Anisidine + 2,6-dibromo-4-nitrophenol | 1:1 | 6.95 and 6.80 | 6.66 |
| 12. | para-Anisidine + 2,6-dibromo-4-nitrophenol | 1:1 | 6.78 and 6.42 | 6.66 |
| 13. | Pyridine + 2,6-dibromo-4-nitrophenol | 1:1 | 7.68 and 7.57 | 7.43 |
| 14. | Quinoline + 2,6-dibromo-4-nitrophenol | 1:1 | 6.23 and 6.42 | 6.57 |
| 15. | Butylamine + 2,6-dibromo-4-nitrophenol | 1:1 | 7.90 and 7.89 | 7.57 |
| 16. | Benzylamine + 2,6-dibromo-4-nitrophenol | 1:1 | 7.10 and 7.30 | 7.18 |
| 17. | Tribenzylamine + 2,6-dibromo-4-nitrophenol | 1:1 | 5.22 and 5.60 | 5.79 |
Such coloration indicates that the bromonitrophenols entered into reaction with the amines in the quinoid form (aci-form).
The synthesized compounds were tested for bactericidal action. The results of the tests (see Table 2) show that complexes of amines with 2,6-dibromo-4-nitrophenol are more active than those with 2-bromo-4-nitrophenol. In antibacterial action the compounds are arranged in the following series: complexes of pyridine, para-anisidine, quinoline, ortho-anisidine, naphthylamines, tribenzylamine. As is evident from the data presented, the bactericidal properties of the complex depend both on the composition and structure of the amine and on the phenol. At the same time, complex formation has a significant influence on the activity of the compound.
As is evident from Table 2, the complexes more often possess a stronger action than the individual components.
Experimental Part
Synthesis of the Starting Substances
Benzylamine was obtained from benzyl chloride and urea [3]. Alpha- and beta-naphthylamines, benzidine, phenylenediamine, ortho- and para-anisidines, pyridine, quinoline, and tribenzylamine were taken in ready-made form and purified by distillation or recrystallization.
2-Bromo-4-nitrophenol was obtained by bromination of para-nitrophenol with dioxane dibromide [4].
2,6-Dibromo-4-nitrophenol was obtained by bromination of para-nitrophenol in acetic-acid medium [5].
Preparation of Complex Compounds
The complexes were most often obtained by mixing saturated benzene solutions of the starting substances. The products of interaction precipitated, were recrystallized, and then analyzed for nitrogen by the modified Kjeldahl method [6]. A brief description of the compounds obtained is given below. The composition and analytical data are indicated in Table 1.
Complex of alpha-naphthylamine with 2-bromo-4-nitrophenol
Yellow-green crystals, m.p. 122–123°. Recrystallized from dilute alcohol (2:1). Readily soluble in alcohol, chloroform, and dioxane. Sparingly soluble in benzene and water.
Complex of beta-naphthylamine with 2-bromo-4-nitrophenol
Light-yellow needles, m.p. 157–158°. Recrystallized from benzene. Soluble in ether, acetone, and chloroform. Sparingly soluble in dilute alcohol (1:1) and water.
Complex of benzidine with 2-bromo-4-nitrophenol
Yellow lustrous crystals, m.p. 145–147°. Recrystallized from benzene. The substance is readily soluble in alcohol, ether, and acetone. Sparingly soluble in chloroform and water.
Complex of para-phenylenediamine with 2-bromo-4-nitrophenol
Greenish-yellow crystals which, after recrystallization from benzene, melt at 172° (with decomposition). The compound is soluble in methyl and ethyl alcohol, sparingly soluble in acetone, chloroform, and water.
Complex of ortho-anisidine with 2-bromo-4-nitrophenol
Isolated from an excess of ortho-anisidine. Yellow crystals, m.p. 59–60°. Soluble in alcohol, ether, benzene, acetone, and carbon tetrachloride. Sparingly soluble in water.
Complex of beta-naphthylamine with 2-bromo-4-nitrophenol
Obtained by pouring together saturated aqueous-alcoholic (1:1) solutions of the components. Yellow needles with m.p. 88–89°. Soluble in alcohol, ether, benzene, and acetone; poorly soluble in water.
Complex of pyridine with 2-bromo-4-nitrophenol
Thin yellow needles with m.p. 81–82°. Recrystallized from benzene. Soluble in alcohol, ether, acetone, and benzene. Less readily soluble in water and insoluble in chloroform.
Complex of alpha-naphthylamine with 2,6-dibromo-4-nitrophenol
Bright-yellow crystals with m.p. 142–143°. Recrystallized from ligroin. Soluble in chloroform, ether, and acetone; poorly soluble in water.
Complex of beta-naphthylamine with 2,6-dibromo-4-nitrophenol
Long crystals of bright-yellow color with m.p. 161–161.5°. Recrystallized from ligroin. Readily soluble in ether, acetone, benzene, and chloroform. Poorly soluble in water.
Complex of benzidine with 2,6-dibromo-4-nitrophenol
Yellow crystals with an orange tint. Melting point 177.5–178.5°. Soluble in methyl and ethyl alcohol, benzene; poorly soluble in water.
Complex of ortho-anisidine with 2,6-dibromo-4-nitrophenol
Obtained from an excess of o-anisidine. Light-yellow needles with m.p. 143–144°. Recrystallized from benzene. Readily soluble in acetone, ether, and chloroform; less readily soluble in benzene; poorly soluble in ligroin and water.
Complex of para-anisidine with 2,6-dibromo-4-nitrophenol
Light-yellow crystals with m.p. 168–169°. The substance is poorly soluble in benzene, ligroin, and water.
Complex of pyridine with 2,6-dibromo-4-nitrophenol
Light-yellow crystals with m.p. 136–137°. Readily soluble in acetone, chloroform, and benzene. Less readily soluble in water and ligroin.
Complex of quinoline with 2,6-dibromo-4-nitrophenol
Bright-yellow crystals with an orange tint, melting at 146–147°. The substance is readily soluble in acetone, ether, and chloroform. Less readily soluble in ligroin and water.
Complex of butylamine with 2,6-dibromo-4-nitrophenol
Isolated from an excess of butylamine. Crystals (small cubes under the microscope) of bright-yellow color with m.p. 157–158°. Readily soluble in alcohol and acetone; poorly soluble in benzene, chloroform, and water.
Complex of benzylamine with 2,6-dibromo-4-nitrophenol
Yellow crystals with m.p. 192–193° (partial sublimation begins at 184°). The compound is poorly soluble in benzene, ligroin, and chloroform. More readily soluble in acetone and water.
Complex of tribenzylamine with 2,6-dibromo-4-nitrophenol
Bright-yellow crystals with m.p. 137–138°. Recrystallized from ligroin. Soluble in benzene, acetone, ether, and chloroform. Poorly soluble in water.
Microbiological investigation
The bactericidal action was determined by the suspension method, with inoculation of Escherichia coli into meat-peptone broth. Phenol resistance of the strain was 20 min in a 1:90 phenol solution.
Not the phenol coefficient, but the active concentration and time of action were determined [7, 9]. The results are given in Table 2.
Table 2
| No. | Substance | Concentration, % | Solvent | Exposure, 20 min | Exposure, 40 min |
|---|---|---|---|---|---|
| 1. | alpha-Naphthylamine--2-bromo-4-nitrophenol | 0.133 | Ethanol 20% + 0.25% OP-7 | -- | -- |
| 2. | beta-Naphthylamine--2-bromo-4-nitrophenol | 0.13 | Methanol 30% | -- | -- |
| 3. | Benzidine--2-bromo-4-nitrophenol | 0.20 | Acetone 10% | -- | -- |
| 4. | Phenylenediamine--2-bromo-4-nitrophenol | 2.0 | Ethanol 20% + 0.25% OP-7 | -- | -- |
| 5. | ortho-Anisidine--2-bromo-4-nitrophenol | 0.183 | “ | + | + |
| 6. | para-Anisidine--2-bromo-nitrophenol | 0.154 | “ | +(--) | + |
| 7. | Pyridine--2-bromo-4-nitrophenol | 0.127 | “ | + | + |
| 8. | alpha-Naphthylamine--2,6-dibromo-4-nitrophenol | 0.121 | Ethanol 25% + 0.25% OP-7 | + | -- |
| 9. | beta-Naphthylamine--2,6-dibromo-4-nitrophenol | 0.122 | “ | + | + |
| 10. | Benzidine--2,6-dibromo-4-nitrophenol | 0.169 | “ | -- | -- |
| 11. | ortho-Anisidine--2,6-dibromo-4-nitrophenol | 0.163 | Ethanol 25% + 0.25% OP-7 | -- | -- |
| 12. | para-Anisidine--2,6-dibromo-4-nitrophenol | 0.123 | “ | + | + |
| 13. | Pyridine--2,6-dibromo-4-nitrophenol | 0.094 | “ | + | + |
| 14. | Quinoline--2,6-dibromo-4-nitrophenol | 0.14 | “ | + | + |
| 15. | Butylamine--2,6-dibromo-4-nitrophenol | 0.612 | “ | -- | + |
| 16. | Tribenzylamine--2,6-dibromo-4-nitrophenol | 0.145 | “ | -- | + |
| alpha-Naphthylamine | 0.5 | “ | + | + | |
| beta-Naphthylamine | 0.493 | “ | -- | -- | |
| Benzidine | 0.42 | “ | -- | -- | |
| para-Phenylenediamine | 2 | “ | -- | -- | |
| ortho-Anisidine | 0.5 | “ | -- | + | |
| para-Anisidine | 1 | “ | -- | -- | |
| Pyridine | 1 | “ | -- | -- | |
| Quinoline | 2 | “ | -- | -- | |
| 2-Bromo-4-nitrophenol | 0.5 | “ | -- | + | |
| 2,6-Dibromo-4-nitrophenol | 0.25 | “ | -- | -- |
DESIGNATIONS: plus \((+)\) denotes the absence of growth of the test organism (i.e., the presence of bactericidal action); minus \((--)\) denotes the presence of growth of the test organism; plus and minus \((\pm)\) denotes growth of the intestinal bacillus in one replicate and absence of growth in the other replicate.
Conclusions
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Seventeen complex compounds not described in the literature were obtained, and their bactericidal action was determined.
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It was shown that complex formation sometimes intensifies the action of the compound, and sometimes weakens it.
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