Analysis of sulfoxylated methyl esters (Φ-MES): Sulfonic acid composition and isomer identification

Abstract

Derivatization of a C 12 Φ-methyl ester sulfonic acid by using iodide-trifluoroacetic anhydride in dimethylformamide in a one-step reaction yielded derivatized sulfonic thiotrifluoroacetates. The latter have been analyzed by gas chromatography-mass spectrometry (MS) and liquid chromatography-MS techniques so that, for the first time, the acid composition and the mono sulfonic acid isomer distribution are shown.Paper no. S1298 in JSD 6, 151-154 (April 2003).KEY WORDS: C 12 Φ-sulfoxylated methyl ester, composition, derivatization, isomer identification.In our previous work (1), a C 16 Φ-methyl ester sulfonic acid (Φ-MES C 16 ) sample was derivatized by methylation with trimethylorthoacetate in excess to give the dimethylester sulfonate. Different analytical techniques were used to analyze the sample, such as gas chromatography (GC)-mass spectrometry (MS), 1 H nuclear magnetic resonance (NMR), liquid secondary ionization mass spectrometry (LSIMS), and tandem MS. The main conclusions drawn from that investigation were as follows: (i) The SO 3 group was positioned randomly. (ii) GC-MS showed the presence of at least 11 isomers that could not be characterized. (iii) 1 H NMR indicated that the major species present contained one CHSO 3 and one CH 2 CO 2 group, confirmed the presence of different isomers, and suggested the presence of polysulfonates. (iv) LSIMS and LSIMS/MS confirmed the presence of CH 3 (CH 2 ) m CH(SO 3 Me)(CH 2 ) n CH 2 CO 2 Me (M.W. = 364 where m + n = 12); very little α or β substitution; and the presence of polysulfonated species of the forms CH 3 (CH 2 ) m CH(SO 3 Me)(CH 2 ) n CH(SO 3 Me)(CH 2 ) p CH 2 CO 2 Me and CH 3 (CH 2 ) m C(SO 3 Me) 2 (CH 2 ) n CH 2 CO 2 Me. Probably as a result of the instability of the derived methyl esters, the research (1) could not be completed and the identification of each isomer remained a goal to be reached.Therefore, in the present investigation a C 12 fatty acid methyl ester was sulfoxidized with SO 2 , O 2 , and ultraviolet light of 257.3 nm wavelength as described previously (2). The sulfonic acid was further extracted from the reactor outlet product with n-hexane as described previously (3), and a different derivatization technique was applied using potassium iodide and trifluoroacetic anhydride (TFAA) (4).Although the random position hypothesis was confirmed for Φ-MES C 16 (1), the present work describes the sulfonic acid composition and identifies each positional isomer for the first time by means of GC-MS and liquid chromatography (LC)-MS. EXPERIMENTAL PROCEDURESDerivatization of Φ-MES C 12 . According to a method developed by Li and Lin (5) and applied by Pratesi et al. (4), a sulfonic acid methyl ester sample, obtained through sulfoxidation (2) and further hexane extraction (3), was derivatized by the TFAA/potassium iodide method (4), and the derivatives were analyzed by GC-MS and LC-MS [electrospray ionization (ESI) source].In this procedure (4), the sulfonic group is first reduced to an alkyl-thiol group. Then the trifluoroacetic acid group is added to ...

Study of the electrochemical oxidation and reduction of C.I. Reactive Orange 4 in sodium sulphate alkaline solutions

“…Both samples were subjected to a derivatisation process in order to turn sulphonated species (resulting from electrochemical reduction) into more volatile products. For his purpose, the sulphonic groups were chemically reduced to thiol groups using iodidetrifluoroacetic anhydride [65,66]. It was observed that both samples presented the characteristic peaks of derivatized 2-amine-1,5-naphthalenedisulphonic acid (figure not shown).…”

Performance of Φ‐Sulfo Fatty Methyl Ester Sulfonate Versus Linear Alkylbenzene Sulfonate, Secondary Alkane Sulfonate and α‐Sulfo Fatty Methyl Ester Sulfonate

“…Two main conclusions were drawn: the palmitic acid U-MES (U-MES C16) could be used as an LAS partner in detergent formulations and the C16 alkyl chain was the optimal length. Since then, progress has been made concerning the development of a procedure for the separation of reaction products [4] and analysis [5,6]. These investigations have led to products with fewer impurities.…”

Characterization of alcohol ethoxylates as alcohol ethoxy sulfate derivatives by liquid chromatography‐Mass spectrometry

“…A method has been described to characterize the major anionic surfactant linear alkylbenzene sulfonate after derivatization by gas chromatography-mass spectrometry (GC-MS) (1). That method also has been applied to the analysis of sulfoxylated methyl esters (2). In this paper, the development of analytical methods to characterize surfactants is continued with the characterization of alcohol ethoxylates (AE).…”