Cholesteryl Benzoate Synthesis Lab Report

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Synthesis of a Liquid Crystal – Cholesteryl Benzoate Introduction The acyl chloride is a convenient reactant when undertaking ester synthesis, this is because it is highly reactive. Therefore, it can drive the reaction to completion and ensure a high yield. The high reactivity of the acyl chloride is due to the electronegative chlorine atom which pulls the electrons towards it in the C-CI bond. Furthermore, this makes the carbon atom more electrophilic and therefore easier for nucleophiles to react with. The chloride ion is a weak base and therefore acts as a good leaving group. Finally, the reaction involving an acyl chloride is irreversible, leading to the completion of the reaction and therefore the desired product, which in this case is …show more content…

In a fume cupboard using a graduated pipette, 3 mL of pyridine was added to the conical flask, followed by 0.41 mL of benzoyl chloride. The solid produced in the conical flask was yellow and had a creamy texture. The mixture was then heated on a steam bath for 10 minutes and then cooled in a beaker of ice-cold water to improve recovery and ensure full recrystallisation. A 15 mL aliquot of methanol was then added to the mixture and the solid product collected under suction filtration in a Büchner funnel. The solid was then washed with two 20 mL aliquots of methanol and then dried again under suction filtration. The solid was then further dried in a vacuum desiccator for 30 …show more content…

The melting point of transition state two was 155 – 160 °C, the sample was clear and liquid. A 0.011 g sample of cholesterol and 0.012 g sample of cholesteryl benzoate were dissolved in dichloromethane, in two separate test tubes. The dichloromethane was used as an elution solvent in the TLC procedure. A TLC was then performed on the two solutions. The results of the TLC are shown in Figure 3. Rf = distance moved by spot ÷ distance moved by the solvent front Cholesterol – Rf = 4 mm ÷ 45 mm = 0.08 Cholesteryl Benzoate - Rf = 25 mm ÷ 45 mm = 0.55 The spectrum of the product (Figure 4) was then run using an infra-red spectrometer: The peak at 710.81 cm-1 corresponds to a C-H bond (arene), this is directly attached to the ester group produced during synthesis. The peak at 1451.35 cm-1 corresponds to the C-H bond (alkyl), the alkyl groups are directly attached to the main hydrocarbon

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