Studies on Synthesis of Aromatic Schiff Bases. Part-V. Evaluation of Antifungal Potential of Ketimines from 5-Chloro-2-hydroxy-4-methyl-acetophenone†

 

C. J. Patil¹*, Manisha C. Patil², Mrunmayee C. Patil³

¹Smt. G. G. Khadse College, Muktainagar, Dist-Jalgaon-425 306, M.S., India

²Dr. A. G. D. Bendale Mahila College, Jalgaon-425 001, M.S., India

³Dept. of Pharma. Sci. and Tech., Nathalal Parekh Marg, Institute of Chemical Technology,

Matunga, Mumbai-400 019, M.S., INDIA.

 

Abstract:

The condensed reaction of aromatic ketone, 5-Chloro-2-hydroxy-4-methyl-acetophenone with aniline derivatives viz. 2,3-Dimethyl-aniline, 2,4-Dimethyl-aniline, 3,4-Dimethyl-aniline and 2,5-Dimethyl-aniline to yield a ketimines, CJ-1 to CJ-4. These were analyzed by employing the techniques such as thin layer chromatography(TLC) and UV-Vis spectra. After confirming their desired molecular studies, these novel ketimines were studied for their antifungal potential.

 

 

INTRODUCTION:

The azomethines are very important synthetic intermediates. Survey of the past literature [1-2] revealed that the chemistry of multiple bonds has achieved an enormous developments, as these compounds are useful in industrial and biological field via cycloaddition reaction [3] and condensation reactions[4]. From the extensive literature survey it is well known that the organic compounds comprising of the >C=N-, >C=C< and >C=O display the biological activity[5]. The ketone undergo condensation reaction with acetyl acetone[6-7]. Recently, we have reported[8] formation of ketimines from o-Hydroxy-acetophenone and different anilines.

 

In the present work, the condensation reaction of rare aromatic ketone, 5-Chloro-2-hydroxy-4-methyl-acetophenone with aniline derivatives viz. 2,3-Dimethylaniline, 2,4-Dimethylaniline, 3,4-Dimethylaniline and 2,5-Dimethylaniline each of reacted to give formation of ketimine, as per the Scheme-1. On confirming their desired molecular studies, these ketimines were studied for their antifungal potential against antifungal strains A. Niger(plant fungi) and C. albicans(animal fungi).

 

 

 

† Partly presented as a poster at 3^rd Global Sustainable Biotech Congress-2014 – International Conference, Sponsored by NMU, Jalgaon and Global Biotech Forum, Nagpur and Cetys Univ., Mexico, at NMU, Jalgaon on 1-5 Dec. 2014.

Scheme of Synthesis:

The proposed general reaction of forming the target compounds is depicted in the Scheme-1.

 

R- = -2,3-(CH₃)₂ (CJ-1); -2,4-(CH₃)₂ (CJ-2); 3,4-(CH₃)₂ (CJ-3) and -2,5-(CH₃)₂ (CJ-4)

 

EXPERIMENTAL:

Chemicals and Reagent:

The raw materials a rare ketone, 5-Chloro-2-hydroxy-4-methyl-acetophenone with aniline derivatives viz. 2,3-Dimethyl-aniline, 2,4-Dimethyl-aniline, 3,4-Dimethylaniline and 2,5-Dimethyl-aniline were of synthesis grade, used for the preparation of ketimine. The solvents absolute alcohol(ethanol), toluene and methanol used during synthesis, TLC and UV-Vis spectra. The reactions were monitored by employing the techniques such as TLC on aluminium plates coated with silica gel 60 F 254 (Merck) and UV-Vis monitored on Shimadzu-1800 spectrophotometer. The antifungal strains A. niger (NCIM-618) and C. albicans(NCIM-3557) were purchased from National Collection of Industrial Microorganisms (NCIM) NCL, Pune.

 

General Procedure for the Synthesis of Ketimines:

The condensation reaction of aromatic ketone, 5-Chloro-2-hydroxy-4-methyl-acetophenone with aniline derivatives viz. 2,3-Dimethylaniline, 2,4-Dimethylaniline, 3,4-Dimethylaniline and 2,5-Dimethylaniline each of 0.001 mole in toluene on reflux for about 5-6 hrs(clear TLC) using Dean and Stark apparatus, gave formation of ketimines[9-13]. The reaction completion is monitored by employing the techniques such as TLC on aluminium plates coated with silica gel 60 F254. The novel products obtained were recrystallized in absolute alcohol.

 

The UV-Vis spectra were recorded on Shimadzu-1800 spectrophotometer in alcohol. The structural assignment of the products was based respectively on the elemental (CHN) analysis.

 

Antifungal Potential:

After confirming their desired molecular studies, these ketimines were studied for their antifungal activity using A. niger (NCIM-618) and C. albicans(NCIM-3557)  using disc diffusion method[13-14].

 

RESULTS AND DISCUSSION:

The condensation products of ketone and amines called as ketimines. In the present study, Ketimines from 5-Chloro-2-hydroxy-4-methyl-acetophenone with aniline derivatives viz. 2,3-Dimethylaniline, 2,4-Dimethylaniline, 3,4-Dimethylaniline and 2,5-Dimethylaniline were synthesized, CJ-1 to CJ-4. The progress of reactions was monitored by TLC plate coated with Silica gel 60 F254, visualized by UV cabinet or iodine vapour. These products were of yellow to brown in colour. The obtained products were purified by column chromatography on 60-120 Silica gel. The purity of the compounds was ascertained by melting point determinations. Their TLCs were recorded on aluminium plates coated with silica gel. The Product details with yield for synthesized Ketimines, CJ-1 to CJ-4, is shown in Table-1.

 

Table 1: The Product details with yield for Synthesized Ketimines, CJ-1 to CJ-4, derived from 5-Chloro-2-hydroxy-4-methyl-acetophenone.

*Isolated yield

 

 

The data of the products showing results of their analytical details such as colour, physical constants and TLC for the Ketimines, CJ-0 to CJ-4, are depicted in Table-2. All the compounds were obtained in high purity. The progress of reactions was monitored using TLC, indicated single spot for the products as visualized by iodine vapour or UV cabinet. The purity of the compounds was ascertained by melting point determination(open capillary method) which are uncorrected. TLC indicated single spot for the preparation of final compounds, CJ-1 to CJ-4, compared with the starting raw material. Thus the synthesized compounds indicate the homogenicity.

 

Table 2: The Physical and Analytical data for Elemental Analysis of the Synthesized Ketimines, CJ-1 to CJ-4, derived from 5-Chloro-2-hydroxy-4-methyl-acetophenone.

Product Code	Colour	m.p. 0C	Results of TLC analysis	Micro-analysis (Elemental) of Ketimines
				% C		% H		% N
				obs.	cal.	obs.	cal.	obs.	cal.
CJ-1	Bistre brown	83.2-85.1	Single Spot product	70.85	70.95	6.24	6.30	4.96	4.87
CJ-2	Old moss green	63.8-64.9	Single Spot product	70.86	70.95	6.28	6.30	4.88	4.87
CJ-3	Process yellow	61.2-63.5	Single Spot product	70.91	70.95	6.29	6.30	4.94	4.87
CJ-4	Gamboge Orange (Brown)	52.2-53.8	Single Spot product	70.90	70.95	6.29	6.30	4.82	4.87

 

 

The data for the elemental analysis of the synthesized Ketimines, CJ-1 to CJ-4, are indicated in Table-2. All the compounds gave satisfactory elemental analysis. The values are in close agreement with the calculated values, expected for the desired molecular formula and are in 5 % in statistics. Similar observations were noted[11-12] earlier. The pictorial presentation of the novel ketimines, CJ-0 to CJ-4, is as depicted in Table-3.

 

 

Table 3: Pictorial representation of the novel Ketimines(Recrystallized), CJ-1 to CJ-4, derived from 5-Chloro-2-hydroxy-4-methyl-acetophenone.

 

 

 

Solvent used for Recrystallization: Alcohol:

Spectral Characterization:

The typical UV-Vis Spectra for the series for Ketimines synthesized, CJ-1 to CJ-4, are depicted in the Fig.-1. In addition to this the compounds, CJ-1 to CJ-4 were also characterized by the UV-Vis spectral analysis and the results obtained are reported in the Table 4.

 

 

Fig. 1 Typical UV-Vis Spectra for the series of novel Ketimines synthesized, CJ-1.

 

On the basis of the foregoing discussion and based on the TLC spectral observations, the structures of the synthesized compounds are assigned. The Table 4 also indicates the assigned structures from the spectral results.

 

The UV-Vis spectra were recorded, from freshly prepared methanolic solutions having the concentration             1.500 x 10^-4 (CJ-1 to CJ-4) All the studied Ketimine compounds showed three absorption peaks in UV-Vis spectra in methanol in the studied range 500 nm to 200 nm. In the UV-Vis spectral analysis of ketimines shows the two to three peaks in the studied range. These are attributed to n®p* and p®p* transitions due to presence of varied auxochrom group (auxochrome) and >C=N- group transitions and aromatic phenyl ring transition of moderate energy. Similar observations were marked earlier[8, 10, 11, 13]. The molar extinction coefficients(ε_max) were also determined and noted in the Table-4. The spectral data are in close agreement with the structures of the synthesized compounds.

 

On the basis of the foregoing discussion and based on the TLC with UV-Vis spectral observations, the structures of the synthesized compounds were decided as below.

 

 

Table 4 : The Spectral Data for Synthesized Ketimines, CJ-1 to CJ-4, derived from 5-Chloro-2-hydroxy-4-methyl-acetophenone.

Antifungal Activity:

After confirming the desired molecular studies, these Ketimines, CJ-0 to CJ-4, were studied for their antifungal activity by subjecting to in vitro antifungal activity against the strain A. niger (NCIM-618) and C. albicans (NCIM-3557) using disc diffusion method [13-15]. The results of zone of inhibition (in mm) are depicted in Table 5.

 

Table 5: The Antifungal activity screening for Synthesized Ketimines, CJ-1 to CJ-4, derived from 5-Chloro-2-hydroxy-4-methyl-acetophenone.

Name of Strain	A. niger (NCIM-618) a plant fungi				C. albicans (NCIM-3557) a animal fungi
Concn.(µg/ml)  →Comp. ID ↓	100	150	200	500	100	150	200	500
CJ-1	8	9	9	11	10	11	10	12
CJ-2	10	11	10	12	10	11	12	14
CJ-3	8	10	10	13	10	11	12	13
CJ-4	6	7	8	10	7	9	11	13
Standard drug Fluconazole (+ ve control)	15	16	16	18	23	25	26	28
Sterile distilled water (- ve control)	- ve

 

Graphical representation of the antifungal activity, after 72 hrs, is depicted in Fig. 2. Fig. 2A indicated the graphical representation of Antifungal Activity of synthesized Ketimines using different strains, against A. niger (NCIM-618). Fig. 2B indicated the graphical representation of Antifungal Activity of synthesized Ketimines using different strains, against C. albicans(NCIM-3557).

 

 

Fig. 2A. Antifungal Activity of synthesized Ketimines using different strains, against A. niger after 72 hrs.

 

 

Fig. 2B. Antifungal Activity of synthesized Ketimines using different strains, against C. albicans after 72 hrs.

Glimpses of antifungal study:

Ÿ  All the compounds showed some activity at all studied concentration, activity is low at lower and high at higher concentration.

Ÿ  Compound, CJ-3, is most active against A. niger at higher (500 µg/dic)concentration while CJ-2 is most active against C albicans.

Ÿ  Compound, CJ-4 is lowest active against both at low concentration(100 µg/dic).

Ÿ  All the compounds studied, except CJ-2 and CJ-3 are moderately active against A. Niger and C albicans  respectively.

 

CONCLUSION:

The present study demonstrated the synthesis of Ketimine from a rare Ketone, 5-Chloro-2-hydroxy-4-methyl-acetophenone is reacted with anilines derivative viz. 2,3-Dimethyl-aniline, 2,4-Dimethyl-aniline, 3,4-Dimethyl-aniline and 2,5-Dimethyl-aniline reacted to yield ketimine. Four ketimines were synthesized and characterized on the basis of analytical and spectral data. These compounds will be useful as building block by organic researchers in the near future. Screening of these compounds against pathogenic microorganism reveals that these compounds  have the different capacity(differently inactive to moderately active) of inhibiting metabolic growth of microorganisms viz. A. niger (NCIM-618) and C. albicans(NCIM-3557) to different extent. The antimicrobial activity of the compound is also dependent on the nature of substituent present on the aromatic ring. The compound CJ-2 is active against A. niger and C. albicans while CJ-4 is inactive against A. niger and C. albicans. The data obtained will be useful for the society to study their further studies for New Researchers.

 

ACKNOWLEDGEMENTS:

One of the authors (CJP) is thankful to Vice Chancellor, NMU, Jalgaon for sanctioning the short research project under VCRMS Scheme (F. No.: NMU/11A/VCRMS/Budget-2012-13/Science-07/108/2013, dated 30.03.2013). They are also thankful to the Management and Principal of their College for the permission of the present work.

 

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Received on 13.10.2017       Modified on 18.12.2017 Accepted on 06.01.2018      ©A&V Publications All right reserved Research J. Science and Tech. 2018; 10(2):125-130. DOI: 10.5958/2349-2988.2018.00018.9