Novel synthesis of 4-allyl-2-methoxyphenyl pentadecanoate

Eugenol (0.8313g, 5.0627 mmol) and pentadecanoic acid (1.357g, 5.598 mmol) were heated under reflux (90 °C) with medium stirring in DMAP (61mg, 0.5 mmol) and EDC.HCl (1.25g, 6.5 mmol) dissolved in acetonitrile (35 mL). After 45 minutes, TLC (eluent: 1-part ethyl acetate to 4-parts hexane) showed no eugenol remained in the flask. The reaction mixture was colourless. The reaction mixture underwent an organic workup: addition of hexane (20 mL) and two washes with hydrochloric acid (20 mL, 1 M, 20.0 mmol) afforded 3 layers: off-white liquid upper layer, slightly off-white liquid middle layer, and colourless lower layer. Washing twice with sodium bicarbonate (20 mL, 10 wt.%) afforded a cloudy off-white precipitate. Addition of hexane (35 mL) to dissolve the precipitate afforded two layers: cloudy off-white organic liquid and a colourless aqueous liquid. Washing with water (20 mL) and two washes with saturated aqueous sodium chloride (20 mL) afforded two layers: cloudy off-white organic liquid and colourless aqueous liquid. Magnesium sulphate was added to dry the organic liquid affording a colourless liquid. Gravity filtration of the mixture and subsequent rotary evaporation yielded 1.043g (53.68% yield) of a colourless oil. After 25 minutes, the oil crystallised to give white sheets of crystals lining the flask. Crystals were collected and prepared for infrared spectroscopy, by dissolution in acetonitrile, and for 1H NMR spectroscopy, by dissolution in deuterated chloroform. IR: ṽ = 3071.8, 3003.8, 2924, 2853, 1762.2, 1712, 1641, 1602.6, 1508, 1120.8 cm-1. These peaks are indicative of alkene, arene, alkane, ether, and ester functional groups, all of which are present in the prospective molecule – 4-allyl-2-methoxyphenyl pentadecanoate. 1H NMR (CDCl3): the spectrum afforded several signals with chemical shifts (all in ppm) ranging from δ 0.891 to δ 1.800, indicative of a saturated hydrocarbon chain. The integration ratio of this range was approximately 27, agreeing with the saturated hydrocarbon chain of the prospective molecule. There were several well-defined signals: Hj = δ 2.587 (2 H, t, J = 7.2 Hz), Hd = δ 3.399 (2 H, d, J = 6.8 Hz), and Hi = δ 3.829 (3 H, s). The signals at δ 5.125 were likely to be the overlap of Ha ≈ δ 5.125 (1 H, dd) and Hb ≈ δ 5.125 (1 H, dd). The low intensity of the signal at δ 5.984 led to the approximation that Hc ≈ δ 5.984 (1 H, tdd). The signals in the range from δ 6.700 to δ 7.000 were likely to be the overlap of He = δ 6.785 (1 H, d, J = 8 Hz), Hg = δ 6.803 (1 H, s) and Hf = δ 6.955 (1 H, d, J = 8 Hz). The chemical shifts of the 1H NMR (CDCl3) spectrum show strong agreement with the chemical structure of the prospective molecule. The IR and 1H NMR (CDCl3) spectra give a strong indication that the synthesis of 4-allyl-2-methoxyphenyl pentadecanoate was achieved.