The essential oil of Mentha piperata L., brown in color, was extracted by hydrodistillation from leaf stems collected in the southern district of Brazzaville (Bacongo), with a yield of 0.42 %. Analysis by gas chromatography (GC) and by gas chromatography coupled with mass spectrometry (GC/MS) revealed the presence of thirty (30) constituents of which twenty (20) were identified representing a proportion of (93.26 %) of the chemical composition of the total essential oil. The essential oil consists mainly of monoterpenes (92.47 %) with a predominance of oxygenated monoterpenes (89.43 %) dominated by menthol (44.08 %), followed by menthone (14.49 %), menthyl acetate (13.54 %) ), mint furanone 1 (7.81 %) and menthofuran (3.04 %). Hydrocarbon monoterpenes occupy a low level of (3.04 %) characterized by limonene (2.71 %), orthocymene (0.37 %), β-pinene (0.35 %) and α-pinene (0.15 %). Concerning the group of sesquiterpenes, this represents a minimal rate (0.79 %), oxygenated compound are predominant (0.57 %) marked by caryophyllene oxide (0.40 %) and viridiflorol (0.17 %). We note the presence of a single hydrocarbon sesquiterpene, E caryophyllene occupying a small proportion of (0.22 %).Menthone 2,4-dinitrophenylhydrazone was hemi-synthesized by reacting the essential oil of Mentha piperata with 2,4-dinitrophenylhydrazine in the presence of sulfuric acid, a simple, easy method occurring in a rapid time (five minutes ). The rate of conversion of menthone to menthone 2,4-dinitrophenylhydrazone of orange color is 29 %.Analysis of menthone 2,4-dinitrophenylhydrazone by UV-visible spectrophotometry showed an absorption maximum wavelength of 356 nm. The UV-visible spectrophotometric method employed for the determination of this hydrazone is convenient, fast and simple. The hemi-synthesized menthone 2,4-dinitrophenylhydrazone could be useful in the pharmaceutical, agrochemical, perfume and cosmetic industries.
Citation: NDZELI LIKIBI Belline, LOUBAKI Laurent, NSIKABAKA Samuel, OUAMBA Jean-MaurilleS(2021) Selective transformation of menthone from the essential oil of Mentha piperata L. into menthone 2,4-dinitrophenylhydrazone and UV-visible spectrophotometric analysis, Global Journal of Pure and Applied Chemistry Research, Vol.9, No.1, pp.1-20
Keywords: 4dinitrophenylhydrazone, Essential oil, Mentha piperata L., UV-visible spectrophotometry, menthone, menthone 2, wavelength.
