Question

Isolation of Nicotine from Tobacco

1. Why did you add 5 mL of 3 M NaOH to the mixture prior to the steam distillation?

2. How can you tell when steam distillation is complete when a large quantity of an organic compound is steam distilled?

3. Is the nicotine you isolated pure? Provide experimental evidence to support your answer.

Answer 1

Ans-1:

The addition 3M NaOH ensures that all the nicotine present in tobacco sample, is available as a free base for distillation or extraction. Because the Nicotine is having a highly basic nitrogen, hence is susceptible for salt formation with acidic impurities, polyphenols etc. present in the tobacco leaves.

Ans-2:

We can check the steam distillation completion for Nicotine, by using the yellow color ppt formation by picric acid as nicotine dipicrate. A small quantity of the coming distillate to be taken for the above color reaction.

Ans-3:

The purity of the isolated Nicotine can be checkd by the following techniques:

1. Measure the optical rotaion : The [α]D of nicotine is (-)168.5o

2. To see the below structure of Nicotine and correlate the FTIR spectral analysis as shown below:

IR Frequency (cm-1)	Peak Assignment
2970 - 2780	Presence of C-H single bond (alkyl group)
1677	Presence of Aromatic -C=N- double bond
1690	Presence of Aromatic -C=C- double bond
717 - 905	Presence of C-H bond of mono substituted pyridine ring