Preparation of an Acetic Acid Ester
14.1 g of octyl acetate were synthesized from the esterification process using 20.0 ml of acetic acid and 17.9 g of n-octanol. The theoretical yield was 23.8 g of octyl acetate. The percent yield was 59.2%. The purification of the final ester was confirmed by boiling point (186-199°C) and infrared index (nD=1.419). It was a colorless liquid that had a slight fragrance of orange and indescribable chemicals. The Infrared spectra confirmed ester peaks: two C-O peaks at 1045cm-1 and 1241cm-1 and C=O at 1746cm-1 . Introduction:
In this experiment, acetic acid and n-octanol will be used to prepare an ester, octyl acetate, by process of esterification. In addition to octyl acetate, possible side products include: water, unreacted octanol and acetic acid, impurities from crude octyl acetate, and carbon dioxide from the sodium bicarbonate.
C8H17OH + CH3COOH ' C10H20O2 + H2O
Reference handout1 : “Preparation of an Acetic Acid Ester”. An infrared spectra, refractive index and melting point were obtained to determine the final purity of octyl acetate. The purification scheme is attached. Results:
Molecular formula: C8H18O
Molar mass: 130.23g/mole
Density: 0.824 g/mL
Molecular Formula: C10H20O2
Molar Mass: 172.3 g/mol
Density: .873 g/m³
Boiling Point: 199°C
Refractive index: 1.418-1.421
# mL in (0.138 moles/100 mL flask) = (130.2 g/mole)x (0.138 moles Octanol) = 17.9 g of Octanol added to 20mL of glacial acetic acid Tarred flask = 19.8 g + ester = 33.8 g = 14.1 g of Octyl Acetate Boiling Point = 186-199°C Refractive index = 1.419 Discussion:
The final product yielded 14.1 g of octyl acetate. The theoretical yield of octyl acetate from 172 g/mole at 0.138 moles would have been 23.8 g octyl acetate. Therefore, the percentage yield...
References: 1. “Preparation of an Acetic Acid Ester.” Class handout, February 2009.
2. Wikipedia website, “Octanol: Properties.” http://en.wikipedia.org/wiki/Octanol, retrieved via internet, March 13, 2009.
3. Wikipedia website, “Octyl Acetate: Properties.” http://en.wikipedia.org/wiki/Octyl_acetate, retrieved via internet, March 13, 2009.
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