118B Laboratory Manual Experiment G

Post-Laboratory Questions NAME: ___________________________ Organic Chemistry – 118 B Lab Day: M T W Th Experiment G Lab Time: 9:00 am 1:10 pm 4:10 pm 7:10 pm Locker #: ___________________________ TA: ________________________________ 1. Write the full mechanism for the dehydration of 2-methylcyclohexanol. 2. Consider the IR of the starting 2-methylcyclohexanol and the dehydration product. What differences do you see to indicate that a reaction has taken place? The starting material has another peak at approximately 3400 while the dehydration product does not have the peak at 3400. 3. 1. 2-Methycyclohexanol is prepared commercially by catalytic hydrogenation of o-cresol (2- methylphenol) and consists of a mixture of cis- and trans- isomers. Describe how you can determine the ratio of cis- and trans-2-methylcyclohexanols from the 1H NMR spectrum provided. (Hint: What do the peaks at 3.05 ppm and 3.75 ppm represent and what does their integration show?) The peak at 3.75 ppm is less deshielded hence it should be the trans isomer. Furthermore, the peak at 3.05 ppm should be the cis isomer. By looking at the multiplicity of the peaks, we can ascertain the ratio. 2. Give the ratio of the two isomers. cis-:trans - _______1:3_______