N-Methyltaurine

N-Methyltaurine (2-methylaminoethanesulfonic acid) is an aminosulfonic acid which is present as a zwitterion in the crystalline state and in polar solvents (just like amino acids).[1] In contrast to the widespread taurine, N-methyltaurine has been found in nature only in red algae,[2] where it is formed by methylation of taurine. It is suitable for esterification (actually amide formation) with long-chain carboxylic acids to taurides (acylaminoethansulfonaten) because of its high polarity and the relatively good solubility of its alkaline earth metal salts, which are also used as mild anionic surfactants.[3]

N-Methyltaurine

Identifiers
CAS Number	107-68-6
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3306207
ChemSpider	7594
ECHA InfoCard	100.003.192
EC Number	203-510-3
PubChem CID	7882
UNII	1X4943TG5W
CompTox Dashboard (EPA)	DTXSID4025664
InChI InChI=1S/C3H9NO3S/c1-4-2-3-8(5,6)7/h4H,2-3H2,1H3,(H,5,6,7) Key: SUZRRICLUFMAQD-UHFFFAOYSA-N
SMILES CNCCS(=O)(=O)O
Properties
Chemical formula	C3H9NO3S
Molar mass	139.17 g·mol^−1
Hazards
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H314, H315, H318, H319
GHS precautionary statements	P260, P264, P280, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P321, P332+313, P337+313, P362, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation

The synthesis of N-methyltaurine was reported as early as 1878,[4] with methylamine being reacted with the silver salt of 2-chloroethanesulfonic acid. An obvious modification for this reaction is the replacement of the silver salt of 2-chloroethanesulfonic acid by the sodium salt of 2-chloroethanesulfonic acid.[5] The addition of methylamine to sodium vinylsulfonate in aqueous solution gives N-methyltaurine in 85% yield after acidification with acetic acid.[6] The purification of the crude product and preparation of the N-methyltaurine can also be accomplished by passage of the sodium salt solution through a cation exchange resin in its H form and then through an anion exchange resin in its OH form.[7] The reaction of sodium isethionate with methylamine in water at high temperature and pressure yields the sodium salt of N-methyltaurine[8]

which yields pure N-methyltaurine upon saturation with CO₂ and removal of the precipitated sodium bicarbonate.[9]

Properties

N-Methyltaurine is a white powdery solid which is readily soluble in water.

Use

N-Methyltaurine (or its sodium salt) is used as a polar head group in surfactants from the class of taurides (acylaminoethanesulfonates), sometimes also called methyltaurates. The Taurides are characterized by excellent foaming - even in the presence of oil and skin fats - and foam stability, with good skin compatibility and broad pH stability.[10] The market breakthrough for N-methyltaurine as a hair restorer is still pending.[11]

References

1. Kalaitzis, John A; Almeida Leone, Priscila de; Quinn, Ronald J; Healy, Peter C (2003). "Zwitterionic 2-(methylamino)ethanesulfonic acid". Acta Crystallographica Section E. 59 (5): o726. doi:10.1107/S160053680300895X. hdl:10072/6334.
2. B. Lindberg, Methylated Taurines and Choline Sulfate in Red Algae, Acta Chem. Scand., 9, 1955, pp 1323 – 1326.
3. E.W. Flick, Cosmetic Additives: An Industrial Guide, Noyes Publication, Park Ridge, New Jersey, 1991, ISBN 0-8155-1255-4, S. 352.
4. Dittrich, Eugen (1878). "Ueber Methyltaurin und die Bildung von Methyltaurocyamin und Taurocyamin" (PDF). Journal für Praktische Chemie. 18: 63. doi:10.1002/prac.18780180102..
5. Schick, John W; Degering, Ed. F (1947). "Synthesis of Taurine and N-Methyltaurine". Industrial & Engineering Chemistry. 39 (7): 906. doi:10.1021/ie50451a024..
6. US 7049464, T. Kimura et al., "Process for producing of an aminoalkylsulfonic acid and a method of salt exchange for a salt thereof", issued 2006-05-23, assigned to Wako Pure Chemical Industries, Ltd.
7. US 2693488, A.R. Sexton, "Purification of amino alkane sulfonic acids by ion exchange", issued 1954-11-02, assigned to The Dow Chemical Co.
8. US 1932907, O. Nicodemus, W. Schmidt, issued 1933-10-31, assigned to I.G. Farbenindustrie AG
9. Deutsches Patentamt, Auslegeschrift 1 122 540; invent1: E. Elbel et al.; assign1: Farbwerke Hoechst AG, bekanntgemacht am 27. Januar 1962.
10. Clariant-Broschüre: Mild Surfactants, (pdf; 801 kB)
11. EP 1235574, C. Hamada et al., issued 2002-08-28, assigned to Shiseido Co. Ltd.