4,5-Dimethylphenol from 2-Hydroxy-4
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J. Chem. Sci. Ó (2020) 132:88 Indian Academy of Sciences https://doi.org/10.1007/s12039-020-01802-4Sadhana(0123456789().,-volV)FT3](0123456789().,-volV) REGULAR ARTICLE Synthesis and characterization of (E)-2-(1-hydrazonoethyl)-4, 5-dimethylphenol from 2-hydroxy-4,5-dimethylacetophenone DINKAR GAGAREa,* , RAJU PATILb, RAMA LOKHANDEa, POONAM DWIVEDIa and AJAY DESHMUKHa aJaipur National University, Jagatpura, Jaipur 302 017, India bInstitute of Science, Mantralaya, Fort, Mumbai 400 032, India E-mail: [email protected] MS received 18 March 2020; revised 5 May 2020; accepted 7 May 2020 Abstract. This study reports the development of a novel substituted hydrazone prepared from 2-hydroxy- 4,5-dimethylacetophenone and hydrazine in alkaline medium at controlled conditions which yields as cor- responding hydrazone [(E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol]. The structure of synthesized (E)-2-(1- hydrazonoethyl)-4,5-dimethylphenol was elucidated by elemental analysis and spectroscopic techniques like infrared spectroscopy, ultraviolet–visible spectroscopy, high-performance liquid chromatography, proton nuclear magnetic resonance and mass spectrum. Keywords. 2-Hydroxy-4,5-dimethylacetophenone; hydrazone; hydrazine. 1. Introduction nucleophilic although the amino type nitrogen is more reactive. Due to the electrophilic and nucleophilic Hydrazone is the product of hydrazine with simple or properties, hydrazones are widely used in organic substituted acetophenone obtained in the alkaline synthesis.1,12 medium. Hydrazones are a class of organic compounds The hydrazones show a wide range of pharmaceu- 1 1,3,13 which possess the general structure R1R2C=NNH2. tical activities, such as antimalarial, antibacte- Hydrazones are aromatic in nature and shows that one rial,14–16 antidepressant,16 analgesic agents,17,18 aromatic ring linked with a hydrazine group. Hydra- antifungal,19–21 antimicrobial,22–26and anticonvulsant zone molecules play a major role in the heterocyclic agents.27–30 chemistry.2–6 The IUPAC name of hydrazone group is (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol, which possesses a conjugate double bond and a delocalized p 2. Experimental electron on both the benzene rings. Hydrazones are related to ketones and aldehydes by the 2.1 Materials replacement of oxygen with the N-NH2 functional group.3,7,8 They containing an azomethine –NHN=CH The chemicals: 2-hydroxy-4,5-dimethylacetophenone, proton and are synthesized by heating the appropriately hydrazine, methanol, acetic acid, sodium hydroxide, substituted hydrazines/hydrazides with aldehydes and ethyl alcohol, ethyl acetate, n-hexane, methanol, ketones in solvents like ethanol, methanol, tetrahydrofuran, chloroform, DMSO, etc., used in this work were of AR butanol, glacial acetic acid.9,10 These are widely studied Grade, commercially available and used without fur- molecules owing to their ease of preparation and diverse ther purification. pharmacological potential. Hydrazones offers various 11 active potential donor sites, i.e. C=O, N–H and NH2. The C-atom in hydrazone has both electrophilic and 2.2 Preparation of 2-hydroxy-4,5- nucleophilic characters and in both the N-atoms are dimethylacetophenone The 3,4-dimethylphenylacetate was cooled in ice and *For correspondence anhydrous aluminum chloride was add to it. The 88 Page 2 of 8 J. Chem. Sci. (2020) 132:88 reaction mixture was heated for 4–5 h. Subsequently, Device (Model: VMP-AD) in open capillaries and were the reaction mixture was cooled to room temperature. uncorrected. Some physical properties of (E)-2-(1-hy- The AlCl3 decomposed after adding ice cold water and drazonoethyl)-4,5-dimethylphenol are mentioned in concentrated HCl. The solid product obtained was Table 1. filtered and washed with demineralized water until the pH of filtrate was neutral and then dried safely. The purity of the product was checked by Thin Layer 3.1 Mass analysis: (E)-2-(1-hydrazonoethyl)-4,5- Chromatography in solvent ethyl acetate : n-hexane dimethylphenol (80:20) and its melting point was 69–73°C, and yield 63%. Reaction Scheme of 3,4-dimethylphenyl acetate The mass spectrum of (E)-2-(1-hydrazonoethyl)-4,5- is give below Scheme 1 and 1-(2-hydroxy-4,5-dime- dimethylphenol was recorded on Waters Quattro thylphenyl)ethanone is given below Scheme 2. Micro Triple Quad Spectrometer. The mass analysis of (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol shows molecular ion peak (M?/e) correctly corresponding to 2.3 Preparation of substituted hydrazone: (E)-2- molecular formula in Table 2 and the mass spectrum is (1-hydrazonoethyl)-4,5-dimethylphenol shown in Figure 1. The substituted hydrazones were prepared by stirring 1 the equimolar concentration mixture of 2-hydroxy-4,5- 3.2 H NMR analysis: (E)-2-(1-hydrazonoethyl)- dimethylacetophenone (1 mol) and hydrazine hydrate 4,5-dimethylphenol (1 mol) in 150 mL methanol, stirred for 15 min at room temperature and dissolved. The solution was Nuclear resonance spectra of the (E)-2-(1-hydrazo- ° noethyl)-4,5-dimethylphenol was recorded in CDCl3 refluxed for 3 h in presence of acetic acid at 65 C, and 1 then the progress of the reaction was checked by TLC solution and H NMR, shown in Figure 2. The rele- [mobile phase:10% ethyl acetate:n-hexane (10:90)]. vant data on observed chemical shifts together with After the completion of the reaction, the mixture was their assignments are summarized in Table 3. cooled at room temperature. The pale yellow color compound formed was filtered, washed with chilled methanol and dried at 40–45°C. For purification and improving description, the compound was re-crystal- lized in methanol. Reaction scheme preparation of (E)- 2-(1-hydrazonoethyl)-4,5-dimethylphenol is given below Scheme 3. 3. Results and Discussion The (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol was 3.3 Infrared analysis: (E)-2-(1-hydrazonoethyl)- analyzed by Infrared spectroscopy, Ultraviolet–visible 4,5-dimethylphenol spectroscopy, Proton nuclear magnetic resonance, Carbon, Hydrogen, Nitrogen, Sulphur elemental ana- The IR spectra of (E)-2-(1-hydrazonoethyl)-4,5- lyzer, melting point, purity by high-performance liquid dimethylphenol compound was recorded in the region - chromatography, water content and mass spectroscopy. of 4000–600 cm 1 using FTIR spectrometer of model Melting points were recorded using Veego Scientific Agilent Resolutions Pro by direct sampling method. H3C H3C O Cl CH3 160-180°C + O Ethanol H3C O CH3 H3C OH 3,4-dimethylphenol acetyl chloride 3,4-dimethylphenyl acetate Chemical Formula: C H O Chemical Formula: C H ClO 8 10 2 3 Chemical Formula: C10H12O2 Molecular Weight: 122.16 Molecular Weight: 78.50 Molecular Weight: 164.20 Scheme 1. Reaction scheme preparation of 3,4-dimethylphenyl acetate. J. Chem. Sci. (2020) 132:88 Page 3 of 8 88 O H C H C 3 O HCl 3 CH + AlCl3 3 Ethanol H3C O CH3 H3C OH 3,4-dimethylphenyl acetate Aluminium Chloride 1-(2-hydroxy-4,5-dimethylphenyl)ethanone Chemical Formula: C10H12O2 Chemical Formula: AlCl3 Chemical Formula: C10H12O2 Molecular Weight: 164.20 Molecular Weight:133.34 Molecular Weight: 164.20 Scheme 2. Reaction scheme preparation of 2-hydroxy-4,5-dimethylacetophenone or 1-(2-hydroxy-4,5-dimethylphenyl) ethanone. N NH2 O (E) H3C H3C Methanol CH3 CH3 NH2 Acetic Acid NH 2 Reflux H3C OH OH Heat H3C 1-(2-hydroxy-4,5- hydrazine (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol dimethylphenyl)ethanone Chemical Formula: H4N2 Chemical Formula: C H N O Chemical Formula: C H O 10 14 2 10 12 2 Molecular Weight: 32.05 Molecular Weight: 178.23 Molecular Weight: 164.20 Scheme 3. Reaction scheme preparation of (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol. Table 1. Physical properties. Molecular Melting point (upper Hydrazone formula Color Solubility and lower range) yield (E)-2-(1-hydrazonoethyl) C10H14N2O Pale yellow powder Freely soluble in chloroform 63°C–68°C 76% -4,5-dimethylphenol Soluble in methanol, ethanol, DMSO, ethyl acetate Insoluble in water Table 2. Mass analysis. Hydrazone Molecular formula Molecular weight Molecular ion peak (M?/e) (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol C10H14N2O 178.23 179.2 The IR spectral data along with the possible on SPECORD 50 PLUS-233 H 1409C Spectrophoto- assignments of (E)-2-(1-hydrazonoethyl)-4,5-dime- meter, using a quartz cell of 1 cm optical path where thylphenol compound are provided in Table 4, fol- methanol was used as a blank. lowed by IR spectra performed by IR direct solid The UV spectrum is shown in Figure 4. The spectra method, use of Agilent Resolutions Pro and IR spec- shows V (bands maximum in nm) in methanol: 254, trum are shown in Figure 3. 325. 3.4 UV analysis: (E)-2-(1-hydrazonoethyl)-4,5- 3.5 Elemental analysis (CHNS): (E)-2-(1- dimethylphenol hydrazonoethyl)-4,5-dimethylphenol The UV spectra of the (E)-2-(1-hydrazonoethyl)-4,5- Formation of (E)-2-(1-hydrazonoethyl)-4,5-dimethyl- dimethylphenol compound in methanol was recorded phenol was further confirmed by elemental analysis 88 Page 4 of 8 J. Chem. Sci. (2020) 132:88 Figure 1. Mass spectrum of (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol. Figure 2. 1H NMR spectrum of (E)-2-(1-hydrazonoethyl)-4,5-dimethylphenol. J. Chem. Sci. (2020) 132:88 Page 5 of 8 88 Table 3. 1H NMR analysis. Assignments Chemical shift (ppm) Functional group No. of proton Multiplicity a 12.467 –OH 1 Broad, singlet b 7.109 –CH 1 Singlet e 6.736 –CH 1 Singlet c, d, f 2.191–2.211 –CH3 9 Multiplet g 5.184 –NH2 2 Broad, singlet Table 4. IR analysis. Bond/functional group Frequency, cm–1 C–O 1230 C=C (aromatic ring) 1447 C–C 1506 N–H 1594 C–H stretch alkenes 2922 C–H stretch aromatics 3050 O–H 3630 Figure 4. UV spectrum for (E)-2-(1-hydrazonoethyl)-4,5- dimethylphenol.