Letter: Determination of the position of the double bonds in di- unsaturated compounds by means of gas chromatography/mass spectrometry of dimethyl disulfide derivatives

Pèpe, Claude; Sayer, H.; Balcar, Nathalie; Dagaut, J.; Couffignal, R.

doi:10.1255/ejms.50

Cited by 7 publications

(7 citation statements)

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“…The product resulting of the reaction between this compound and the DMDS is a four-membered cyclic thioether since only one methylene group separates the double bonds [1][2][3][4][5][6].…”

Section: Resultsmentioning

confidence: 99%

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Study of the fragmentation pathways of dimethyl disulfide derivative of 2-methyl-1,4-pentadiene by GC/MS to locate the double bonds in substituted unsaturated compounds

Pèpe¹,

Sayer²,

Ledoux³

et al. 1999

Analusis

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The determination of the double bond positions in mono and diunsaturated esters has been studied by using their dimethyl disulfide (DMDS) derivatives. If the number of methylene groups which separates the two double bonds is less than 4, a cyclic thioether is formed and the fragmentation observed, after electron impact at 70 eV, has permitted unequivocal determination of the double bond positions for alkadienes and esters [1][2][3][4][5][6].The DMDS derivative (a cyclic thioether) of 2-methyl-1,4-pentadiene has been studied by mass spectrometry in a previous paper [7]. The mass spectrum (Fig. 1) shows the presence of a base peak at m/z 113 and fragment ions at m/z 161 and 147 resulting of the loss of CH 3 S • or CH 3 SCH 2 • respectively from the molecular ion. In turn, these fragment ions m/z 161 and 147 lose methanethiol (CH 3 SH) to give respectively the ions at m/z 113 and 99. This loss of CH 3 SH is essential for interpretation of the mass spectra of DMDS derivatives of unsaturated compounds and to locate the double bonds.The structures of the fragment ions at m/z 113 and 99 were investigated by using ab initio calculations, in particular by calculation of the values of the relative energies of the isomeric structures. In each case, the loss of CH 3 SH was considered as a migration of the hydrogen atom bonded to the carbon atom in the β-position relative to the sulfur atom.We report in this work a study of the loss of CH 3 SH by migration of a hydrogen atom no bonded to C in the β-position relative to the sulfur atom. ExperimentalSample preparations and mass spectrometry 2-methyl-1,4-pentadiene and 2,4-dimethyl-1,4-pentadiene (50 µg) were treated in 100 µL of hexane by addition of 100 µL of DMDS and a solution of 20 µL of iodine (60 mg of iodine in 1 mL of diethyl ether). The reaction was carried out in a closed tube for two days at 50 °C. The excess of iodine was reduced with sodium thiosulfate solution (5% in water). The organic phase was removed and the excess of DMDS was evaporated. The dry extract was diluted with 50 µL of hexane and then analysed by GC/MS.To synthesize the 2,4-dimethyl-1,4-pentadiene, 10 mL of a solution of isopropenylmagnesium bromide (0.5 mol L -1 ) in THF were added dropwise under N 2 and moderate stirring to 0.4 mL of 3-chloro-2-methyl-propene, then shaken at room temperature during 12 hours. The mixture was hydrolysed by 1 mL of NH 4 Cl satureted solution, dried over Na 2 SO 4 , and distilled under atmospheric pressure.Electron ionization mass spectra were obtained using a Nermag R10-10 quadrupole mass spectrometer coupled to a Varian Model 3400 gas chromatograph. The sample was Abstract. An experimental study has been employed to examine the loss of CH 3 SH from the dimethyl disulfide (DMDS) derivative of 2-methyl-1,4-pentadiene (cyclic thioether). This loss is particulary important to locate the double bonds in mono, di and tri-unsaturated compounds after addition of DMDS. This work shows that the migration of a H atom in the β or in a other position relative to the sulfur atom...

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“…The product resulting of the reaction between this compound and the DMDS is a four-membered cyclic thioether since only one methylene group separates the double bonds [1][2][3][4][5][6].…”

Section: Resultsmentioning

confidence: 99%

“…If the number of methylene groups which separates the two double bonds is less than 4, a cyclic thioether is formed and the fragmentation observed, after electron impact at 70 eV, has permitted unequivocal determination of the double bond positions for alkadienes and esters [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Study of the fragmentation pathways of dimethyl disulfide derivative of 2-methyl-1,4-pentadiene by GC/MS to locate the double bonds in substituted unsaturated compounds

Pèpe¹,

Sayer²,

Ledoux³

et al. 1999

Analusis

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“…The ions resulting from β-cleavages are able to successively eliminate a number of CH 3 SH molecules depending on the number of methylthio groups retained in the ions. 49 It is to be noted that the addition of DMDS to dienes and trienes does not always proceed to completion and mixtures of various mono-adducts have to be analyzed by GC/MS.…”

Section: Derivatization Of Unsaturated Compoundsmentioning

confidence: 99%

Derivatization in Mass Spectrometry—5. Specific Derivatization of Monofunctional Compounds

Halket

Заикин

2005

Eur J Mass Spectrom (Chichester)

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The present paper is complementary to the foregoing reviews and describes some additional methods of the derivatization of particular functional groups mainly to enhance the structural information content of electron ionization and chemical ionization mass spectra. Derivatization approaches for the modification of unsaturated compounds, alcoholic, carboxylic, carbonyl, amine and other functional groups, are discussed. Derivatization for separation and quantitative determination of chiral enantiomeric compounds is also considered. Preliminary chemical and physical-chemical degradation for structure elucidation of high molecular weight compounds (biopolymers, synthetic polymers) is mentioned. Chemical aspects of derivatizations and characteristic mass spectral features of derivatives are described briefly. Some particular applications of chemical modification, in conjunction with mass spectral measurements for the analysis of various important bioorganic compounds and compounds in biological fluids, air, environmental etc., are considered.

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“…An exception appears to be a chemical reaction using dimethyl disulfide (DMDS) as the derivatization agent. The addition of DMDS to unsaturated compounds in the presence of iodine is an interesting analytical method, which has already been shown to allow location of the positions of double bonds in olefins, unsaturated esters,9–14 natural long chain alkadienes,15 lactones and short chain alkadienes,16–19 using GC/MS. On electron impact, the fragmentation pathway of the ionized adducts is characteristic and permits determination of the positions of the double bonds in mono‐, di‐ and triunsaturated compounds.…”

Section: The Alkynes Studiedmentioning

confidence: 99%

The use of ethanethiol to locate the triple bond in alkynes and the double bond in substituted alkenes by gas chromatography/mass spectrometry

Pèpe¹,

Dif²

2001

Rapid Commun. Mass Spectrom.

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In order to locate the position of the triple bond in alkynes, several dimethyl disulfide (DMDS) derivatives of alkynes were studied. None of these adducts, on EI ionization at 70 eV, allowed the location of the triple bond. However, when DMDS is substituted by ethanethiol, the adducts obtained allow the determination of the position of the triple bond by GC/MS. A similar study of the DMDS derivatives of highly substituted alkenes was carried out. This work showed that the DMDS derivatives, after ionization at 70 eV, do not reveal the position of the double bond if steric effects are important. In contrast, when ethanethiol was used instead of DMDS, the adducts obtained led to the location of the double bond. Copyright © 2001 John Wiley & Sons, Ltd.

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Letter: Determination of the position of the double bonds in di- unsaturated compounds by means of gas chromatography/mass spectrometry of dimethyl disulfide derivatives

Cited by 7 publications

References 0 publications

Study of the fragmentation pathways of dimethyl disulfide derivative of 2-methyl-1,4-pentadiene by GC/MS to locate the double bonds in substituted unsaturated compounds

Study of the fragmentation pathways of dimethyl disulfide derivative of 2-methyl-1,4-pentadiene by GC/MS to locate the double bonds in substituted unsaturated compounds

Derivatization in Mass Spectrometry—5. Specific Derivatization of Monofunctional Compounds

The use of ethanethiol to locate the triple bond in alkynes and the double bond in substituted alkenes by gas chromatography/mass spectrometry

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