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3 5 Trimethylcyclohexanone Lab Report

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Preparation of 3,3,5-trimethylcyclohexanol mixture: Isopropanol (12.5 mL, 163 mmol) and a KOH pellet were added to NaBH4 (17.8 mmol, 673mg) before 3,3,5 trimethylcyclohexanone (20 mmol, 3.16 mL) was added to the suspension. The reaction mixture was stirred (30 minutes, room temp.) and then added to brine (10.0 mL) in a separatory funnel. The product was extracted from the aqueous layer using 10% hexane (3 x10mL) before the combined organic layers were washed with brine (10.0 mL), dried with Na2SO4, and concentrated. The crude product was distilled using a vacuum aspirator to produce a clear, colorless liquid containing cis-3,3,5-trimethylcyclohexanol (1) and trans-3,3,5-trimethylcyclohexanol (2) (BP: ~105°C, 977mg, 38.6% yield), characterized …show more content…

The crude product was identified as 3,3,5 trimethylcyclohexanol based on an analysis of the 1H NMR and IR spectra (Figure 1 and Figure 4). In the IR spectra, a distinct broad OH peak (3356 cm-1) indicates the presence of an alcohol. The peaks of C-H (2952 cm-1), and C-O (1706 cm-1) was hard to identify the crude product due to it being in the fingerprinting region. Using the integration values of 1.11 and 3.27 from the crude product’s 1H NMR spectra, the diastereomeric mixture was identified as a 1:3 ratio of cis-3,3,5-trimethylcyclohexanol to trans-3,3,5-trimethylcyclohexanol. The TLC results from the flash chromatography of the product fractions (fraction 4-6, Fraction 11-13) showed two distinct products based on the differing Rf values of 0.66 and 0.50, supporting the claim that the product exists as a diastereomeric mixture (Figure 5).The fraction set of 4,5, and 6 were identified as trans-3,3,5-trimethylcyclohexanol while fraction set 11, 12, and 13 were identified as cis-3,3,5-trimethylcyclohexanol by 1H NMR spectra (Figure 2-3). The couplet constant of the adjacent peaks in the quartet found at 4.14 ppm (J= 7.17 Hz) were all consistent, showing that the vicinal protons were all equatorial-equatorial or axial-equatorial. Because the angles of the vicinal protons were all the

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