Preparation of Isopentyl Acetate

Results and word of honor Isopentyl propanoate was prepared by refluxing isopentyl intoxicant in excess propanoic acid and knockout sulphuric acid. The ester was obtained by distillation in 62% yield, bp 140-150oC (lit. 156 oC 1). GC analysis of the distillate revealed however traces of the starting alcohol (Figure 1). The esters structure was sustain using IR and 1H proton magnetic resonance spectroscopy. The IR spectrum (Figure 2) shows a strong absorption at 1741 cm-1 consistent with an ester C=O str etcetera vibration. The proton magnetic resonance spectrum (Figures 3 and 4) contains both of the star signs anticipate for this conflate. A triplet at 1. 18 ppm and a quartette at 2. 8 ppm are depute to the propionyl methyl and methylene radical groups, respectively. A doublet at 0. 82 ppm is designate to the two isopentyl methyl groups. A 6 line pattern at 1. 66 ppm is assigned to the methine group (9 lines are expected), and a triplet at 4. 08 and a quartet at 1. 48 ppm are assigned to the OCH2 and CHCH2 methylene groups, respectively. Experimental Preparation of isopentyl propanoate. Isopentyl alcohol (4. 6 mL, 42 mmol), propanoic acid (40 mL, 530 mmol), and concentrated sulfuric acid (1 mL, 18 mmol) were refluxed for 66 minutes. The solution was diluted with water (60 mL) and extracted with ethyl ether (60 mL).The ether layer was washed with sodding(a) aq. NaHCO3 (2 x 60 mL), dried with MgSO4, and distilled at atmospheric pressure to give isopentyl propanoate 3. 8 g (62% from isopentyl alcohol), bp 140-150 oC (lit. 156 oC 1) IR (ATR) cm-1 2960 (vs, CH), 1741 (vs, C=O), 1189 (s, C-O) 1H proton magnetic resonance (C6D6, 400 MHz) ? 0. 92 (d, 6H, J = 6. 8 Hz, CH(CH3)2), 1. 18 (t, 3H, J = 6. 6 Hz, CH2CH3), 1. 48 (q, 2H, J = 6. 6 Hz, CHCH2), 1. 66 (9 lines, 1H, J = 6. 8 Hz, CH), 2. 28 (q, 2H, J = 6. 6 Hz, CH2CO), 4. 08 (t, 2H, J = 6. 8 Hz, OCH2) GC (120 oC, rightfulness column) isopentyl propanoate (4. 8 min), isopentyl alcohol (4. 4 min). Referen ces 1.Mordechai, U. ed. Esthers Ester Handbook, eleventh Ed. , Fruity Publishing, Boca Raton, 1984. E-factor Insert appoint and gage of consumed materials, product, and e-yield here. Figures GC data, IR spectrum, and NMR spectrum label distributively one as a numbered meet (see above) and give the figure an appropriate sur foretell see appendix for additional instructions NMR Exercise Choose one of the molecules listed below. pass away its structure (show all H) and label all protons as A, B, C, (apply the same label to NMR equivalent protons). Examine the online proton NMR spectrum (follow the link the pocketable upper spectrum is the carbon-13 NMR, ignore it).List all shifts associated with the compound do non list shifts for solvent, TMS, etc. , and do not list integrals or coupling patterns. Assign each signal to a particular proton. Do this on your own do not resolve with others. (If you are having trouble with the assignment and would akin some help from others, wor k on a different spectrum from the one that you telephone number in). Turn in 1) the compound name provided below, 2) the structural formula and H labels, 3) the list of shifts and assignments (write the label next to its shift). Do not turn in the spectrum