Esterification

In this lab, n-propyl propionate was synthesized using propanol, concentrated sulfuric acid, and propionic acid resulting in 51.8% yield of n-propyl propionate. The product had a sharp, but tangy pineapple/pear odor. The yield could have been greater, but one possible explanation for the low percent yield was the possible loss of reagents or products due to evaporation during reflux. The reflux head could’ve been lowered to slow the rate of evaporation.The identification of the product was analyzed through infrared spectroscopy(IR). As one would analyze IR there are specific characteristics that one would notice. The first is that an observed spike around 3000 cm^-1that results from the sp³hybridized C-H bond. The second is that no large absorptions are present after 3000 cm^-1, indicating no O-H impurities present. Thirdly, narrow spikes are located around 1750 cm^-1that represent the C=O bond of the ester. Lastly, there is a unique fingerprint between 800 cm^-1to 1500 cm^-1composed of one large spike around 1200 cm^-1and smaller peaks at ~1000 cm^-1, ~1100 cm^-1, ~1350 cm^-1, and ~1450 cm^-1. The spectrum of the product was almost identical to the expected spectrum of n-propyl propionate. The product spectrum, however, had small indent absorptions at 3500 cm^-1indicating the presence of an alcohol O-H impurity. This would suggest that propanol was still present in the final product. The presence of the alcohol could be due to the lack of clarity within the procedure in removing excess water during reflux as well as removing the excess water through washing.