preparation of deet

7/28/2019 Preparation of DEET

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Preparation of DEET

Devin Roy

April 1, 2012

The preparation of N,N-dimethyl-m-toluamide also known as DEET was carried out through the

Schotten-baumann synthesis method. N,N-Diethyl-meta-toluamide, abbreviated DEET, is a slightly

yellow oil. It is the most common active ingredient in insect repellents. It is intended to be applied to the

skin or to clothing, and provides protection against tick bites, mosquito bites, chiggers, and other insects

that can transmit disease. DEET was developed by the United States Army, following its experience of

jungle warfare during World War II. It was originally tested as a pesticide on farm fields, and entered

military use in 1946 and civilian use in 1957. It was used in Vietnam and Southeast Asia.


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Introduction

The SchottenBaumann reaction is a method to synthesize amides from amines and acid

chlorides. Sometimes the name for this reaction is also used to indicate the reaction between an acid

chloride and a alcohol to form an ester. The reaction was first described in 1883 by German chemists

Carl Schotten and Eugen Baumann. In the first step an acid chloride reacts with an amine so that anamide is formed, together with a proton and a chloride ion. Addition of a base is required to absorb this

acidic proton, or the reaction will not proceed. Often, an aqueous solution of a base is slowly added to

the reaction mixture. The name "Schotten-Baumann reaction conditions" is often used to indicate the

use of a two-phase solvent system, consisting of water and an organic solvent. The base within the

water phase neutralizes the acid, generated in the reaction, while the starting materials and product

remain in the organic phase, often dichloromethane or diethyl ether.

Results and Discussion

Chemical # Signal Peaks # of H's Structure

m-toluic acid A 2.5 S 3 CH3-Ph

B 7.6 M 4 4H's on Ph ring

c 11.1 S 1 C-OH

Diethyl

hydrochloride

A 1.5 T 6 CH3-CH2

\

N

/

CH3-CH2

b 3.1 q 4 CH3-CH2

\

N

/

CH3-CH2

DEET A 1.0 T 6 CH3-CH2

\

N

/

CH3-CH2

B 2.1 S 3 CH3-Ph
http://en.wikipedia.org/wiki/File:Preparation_of_DEET.png


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DEET

Continued

C 3.4 Q 4 CH3-CH2

\

N

/

CH3-CH2

D 7.2 M 4 4H's on Ph ring

Chemical cm^-1 Interpretation

m-toluic acid 2867 C-H Sp3 stretch

745 C-H bend(3 adjacent H's)

2500-3200 Carboxylic Acid stretch

1681 C=O stretch

Diethyl hydrochloride 2970 C-H Sp3 stretch

350 N-H stretch

DEET 2970 C-H Sp3 stretch

1632 C=O stretch

796 C-H bend (3 adjacent H's)

No % yield was able to be obtained because at the end of this experiment we still had liquid form DEET

and no solid, so solvent was still present and the concentration was not known precisely. This was done

at the request of Mrs. Williams.

Conclusion

DEET was indeed formed judging from the above NMR and IR spectra intepretations, as well as

the smell present at the end of the experiment. DEET has a very distinctive smell if you've ever used it

outdoors to repel misquitos.

Experimental Section

Addition under reflux was performed on m-toluic acid with thionyl chloride for 20 minutes. HCL

gas evolved and when this ended it signaled the end of this first step. The mix was then cooled in an ice

bath to 10 degrees celsius or below. NaOH was then cooled in an ice bath separately for 5 minutes.

diethylamine hydrochloride and sodium lauryl sulfate was added to said NaOH in small portions while

swirling. This was mixed into the solution from the first section while still on ice and also stirring over

the course of 5 minutes. This was then heated using a hot water bath for approximately 15 minutes. At

this point the solution should be basic. The acid chloride odor should also be gone. The mix was then

allowed to cool to room temperature and transferred to a separatory funnel and extracted with 3

portions of ethyl ether and then washled with NaCL and HCL 1M. the solution was then dried using


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MgSO4 to remove any excess H2O remaining. The excess ethyl ether was then boiled away using the

roto-evap apparatus.

References

www.wikipedia.com

preparation of deet

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