Reduction of Camphor to Isoborneol

By Allan Robinson

Note: Please format the numbers in the formulas to appear as subscripts. Camphor [(CH3)3(CH2)3(CH)(C)2C0] is a waxy, white solid with a strong aromatic odor. Isoborneol [(CH3)3(CH2)3(CH)(C)2CH(0H)] is structurally similar and may be synthesized from camphor. This conversion is commonly performed as an organic chemistry experiment and has a number of synthesis routes. One of the simplest methods of preparation uses sodium borohydride (NaBH4) as a reducing agent.

Change in Chemical Structure

Camphor and Isoborneol differ only by the bonds of a single carbon atom. Camphor is a member of a class of compounds known as a ketone that has a carbon atom that is double bonded to oxygen (C=0). Isoborneol is one of its corresponding secondary alcohols such that this carbon atom has a bond with hydrogen and a bond with the hydroxide ion (H-C-OH). The process of replacing a double-bonded oxygen atom with a hydrogen atom and hydroxide ion is a type of reaction known as reduction. Chemically, a ketone (camphor) may be converted into one of its secondary alcohols (isoborneol) with a reducing agent (sodium borohydride).

Synthesis

Check the sodium borohydride to see if it's still active. Place a small sample of the sodium borohydride in methanol, heat it gently and look for a reaction that produces bubbles. This step is necessary because sodium borohydride reacts readily with water to dissolve into ions of sodium (Na+) and borohydride (BH4-).

Place 100 mg of camphor in a test tube and add 0.5 mL methanol. Shake the test tube vigorously to dissolve the camphor and cautiously add 0.06 g sodium borohydride to the solution. Heat the solution to the boiling point of methanol (68 degrees Celsius) 2 minutes. This should cause the formation of a white solid.

Purification

Purify the solid into isoborneol by first removing the impurities with water and then removing the water. This is accomplished by allowing the solution to cool by itself for several minutes and slowly adding 3.5 mL of ice water to the solution. Remove the resulting liquid with a pipette and add a maximum of 4 mL ether to dissolve the remaining solid. Remove the bottom layer of water with a pipette and remove the remaining water by adding 3 to 4 microspatulas of anhydrous sodium sulfate. Cork the test tube and shake to ensure that all the water is captured by the sodium sulfate. Remove the sodium sulfate by filtering it through a pipette stuffed with cotton. Rinse the test tube with ether and filter the solution again. Allow the contents of the test to evaporate, leaving the isolated isoborneol.

About the Author

Allan Robinson has written numerous articles for various health and fitness sites. Robinson also has 15 years of experience as a software engineer and has extensive accreditation in software engineering. He holds a bachelor's degree with majors in biology and mathematics.