Question

identify what is in Fraction 1 and Fraction 2, which may have a contaminant. You should identify what that contaminant is based on the IR and considering what contaminant is most likely. *The wxpected product is DEET( N,N diethyl-m- toluane).

identify the following iR spectra ... (with respect to “DEET” lab)

5:15 LTE X DEET_ IR_Sp_2019.pdf R. 요 요--요鼎요 Open With Print 5:15 LTE DEET_IR_Sp_2019.pdf Open With Print Fri A,0678 58:34 2019 (GMT-04:00) Fri A r 05 19:18:19 2019 (GMT-04:00) 8 40 8 8 3000 2000 8 Wavenumbers (crn-1)

Answer 1

N,N-diethyl-m-toluamide or N,N-diethyl-3-methylbenzamide is also called as DEET is a insect repellent. It has a benzene ring and amide group is attached to it. One methyl group is attached to the meta position of benzene ring. So, methyl group is meta with respect to the amide group. Structure of DEET written as follows

  

CH CH CH N,N-diethyl-3-methylbenz amide DEET)

Before comparing the IR spectral details of attached one and DEET IR spectra, first we will discuss the IR spectral details of DEET.

• 3500 cm-1 there is no (usually in tertiary amide this signal will be absent) -N-H peak. It means the amide is tertiary in nature.
• 2970 cm-1 there is a sharp C-H sp3 stretch can be seen which corresponds to the methyl group present in the group.
• 2875 cm-1 there is a signal which corresponds to C-H sp2 stretch.
• 1630 cm-1 there is a C=O stretch of amide carbonyl group. Here there is no overlap of N-H bend with C=O stretch signal. It confirms that the amide is tertiary.

Contamination present in the attached IR spectra in the question

• In the attached spectra, you can see the signal at 3400 cm-1 range. So, there is a N-H bond stretch character present in the sample.
• C=O stretch frequency is not clear in the attached IR spectra, and its overlapped with N-H peak at 1625 cm-1
• DEET can be synthesized by reacting n-toluoyl chloride with diethylamine. So, the starting material is still present in the sample, therefore, the taken sample is contaminated because of the presence of traces of starting material.