Dimethylbenzylamine Explained
Dimethylbenzylamine is the organic compound with the formula C6H5CH2N(CH3)2. The molecule consists of a benzyl group, C6H5CH2, attached to a dimethylamino functional group. It is a colorless liquid. It is used as a catalyst for the formation of polyurethane foams and epoxy resins.
Synthesis
N,N-Dimethylbenzylamine can be synthesized by the Eschweiler–Clarke reaction of benzylamine[1] [2]
Reactions
It undergoes directed ortho metalation with butyl lithium:
[C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub> + BuLi → 2-LiC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub>
:LiC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub> + E<sup>+</sup> → 2-EC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub>
Via these reactions, many derivatives are known with the formula 2-X-C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub> (E = SR, PR<sub>2</sub>, etc.).
The amine is basic and undergoes [[quaternization]] with alkyl halides (e.g. hexyl bromide) to give quaternary ammonium salts:[3]
[C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub> + RX → [C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>N(CH<sub>3</sub>)<sub>2</sub>R]+X−
Such salts are useful phase transfer catalysts.
Uses
As the molecule has tertiary amine functionality, two of the key uses are as an epoxy-amine cure enhancement catalyst and also as a polyurethane catalyst.[4] [5] [6] [7]
References
- Icke. R. N.. Wisegarver. B. B.. Alles. G. A.. 1945. β-Phenylethyldimethylamine. 25. Organic Syntheses. 89. 10.15227/orgsyn.025.0089.
- 10.1021/ja01338a041. 1933. Clarke. H. T.. Hans Thacher Clarke. Gillespie. H. B.. Weisshaus. S. Z.. J. Am. Chem. Soc.. 55. 11. 4571. The Action of Formaldehyde on Amines and Amino Acids.
- o-Methylethylbenzyl Alcohol. W. R. Brasen . C. R. Hauser . Org. Synth.. 1954. 34. 58. 10.15227/orgsyn.034.0058.
- Firouzmanesh . Mr . Azar . A Aref . June 2003 . Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC . Polymer International . en . 52 . 6 . 932–937 . 10.1002/pi.1135 . 0959-8103.
- Firouzmanesh . M. R. . Azar . A. Aref . March 2005 . Study of the Effect of BDMA Catalyst in Epoxy Novolac Curing Process by Isothermal DSC . Journal of Reinforced Plastics and Composites . en . 24 . 4 . 345–353 . 10.1177/0731684405033953 . 2005JRPC...24..345F . 93979685 . 0731-6844.
- Zhang . Qian . Hu . Xiang-Ming . Wu . Ming-Yue . Zhao . Yan-Yun . Yu . Chuang . 2018-07-15 . Effects of different catalysts on the structure and properties of polyurethane/water glass grouting materials . Journal of Applied Polymer Science . en . 135 . 27 . 46460 . 10.1002/app.46460. free .
- Benzyldimethylamine (BDMA): Catalyst of Choice with Epoxy Embedding Media . 2003 . 10.1017/s1551929500053104 . Mascorro . José A. . Microscopy Today . 11 . 4 . 47 . free .
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