Inorganic Chemistry

Experiment 2

Title: Preparation of 4-methylcyclohexene from dehydration of 4-methylcyclohexanol (PAGE 561)

In this experiment, 4-methylcyclohexanol undergoes acid-catalyzed dehydration to give 4-methylcyclohexene. The product is distilled from the reaction flask along with the water generated. The distillate is washed with salt solution, dried and distilled.

Required reading: Technique 5 and 6

Technique 12- Extractions, separations and drying agents, Section 12.7, 12.8 and 12.9

Technique 14- Simple distillation

Procedure (add-on reminders):

• Apparatus assembly

o Weight an empty and clean 50ml round-bottom flask (RBF) before you place 7.5ml of 4-methylcyclohexanol in it

o Using graduated pipette, place 7.5 ml of 4-methylcyclohexanol in the RBF

• Dehydration

o Maintain the distillation temperature below 100°C. Continue until only 0.5-0.6 ml of residue remains in the distillation flask or the mixture begins to smoke or bump

• Isolation and drying of the product

o Transfer the distillate to a separatory funnel with the aid of 3ml saturated sodium chloride solution (you don’t have to use centrifuge tube and Pasteur pipette)

• Distillation

o Make sure you get rid of the drying agent before starting with distillation process

o The 25ml RBF use as a receiver must be pre-weigh.

o The boiling point of your 4-methylcyclohexene is the temperature range over which most of the product distills.

• Spectroscopy

o No need to do this part

• Unsaturation test

o This test must be done and record your result and explain them.

The report that you submit must include:

1. Theoretical yield calculation (SHOW WORK)

2. Percentage yield calculation of 4-methylcyclohexene (SHOW WORK)

3. Observed boiling point and literature boiling point of the product.

Question:

Only answer question 1,2 and 5 from the text book.

Additional question:

Show the complete acid-catalyzed mechanism for the dehydration of 2-methylcyclohexanol.