Determination of positions of double bonds in di‐unsaturated esters and a di‐substituted γ lactone by means of GC/MS of dimethyl disulfide derivatives

Pèpe, Claude; Balcar, Nathalie; Dizabo, Pierre; Dagaut, J.; Saliot, A.; Couffignal, R.; Sayer, H.

doi:10.1002/rcm.1290091522

Cited by 11 publications

(9 citation statements)

References 8 publications

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“…These two principal fragmentation pathways are identical with that obtained for the DMDS derivatives of diunsaturated compounds. 8,9 These results allow the determination of the location of the three double bonds.…”

Section: Resultsmentioning

confidence: 99%

“…In each case, for n = 1, 2, or 3, a cyclic thioether is formed and a predictable fragmentation pathway has been demonstrated, allowing an unequivocal determination of the original position of the double bonds and the identification of the derivatives. [7][8][9] For n ≥ 4 four methylthio groups are introduced and, after electron ionization, it is possible to locate the double bonds in symmetrical or unsymmetrical alkadienes and esters. 10 This method has not been used to locate double bonds in triunsaturated compounds, in particular when the number of the methylene groups (n 1 and n 2 ) between the double bonds is < 4.…”

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Determination of Double Bond Positions in Triunsaturated Compounds by Means of Gas Chromatography/Mass Spectrometry of Dimethyl Disulfide Derivatives

Pèpe

Sayer

Dagaut

et al. 1997

Rapid Commun. Mass Spectrom.

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The determination of the positions of double bonds after dimethyl disulfide (DMDS) addition is described for triunsaturated compounds (alkatrienes and an ester). Different DMDS derivatives were studied according to the numbers, n 1 and n 2 , of methylene groups separating the double bonds. When n 1 and n 2 are smaller than four, a bicyclic thioether is formed and a predictable fragmentation pathway is observed in each case after electron ionization, allowing the determination of the positions of the three double bonds and the molecular structure of the compounds.

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Section: Resultsmentioning

confidence: 99%

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Determination of Double Bond Positions in Triunsaturated Compounds by Means of Gas Chromatography/Mass Spectrometry of Dimethyl Disulfide Derivatives

Pèpe

Sayer

Dagaut

et al. 1997

Rapid Commun. Mass Spectrom.

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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].…”

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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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“…Mass spectrometry of dimethyl disulfide (DMDS) adducts of unsaturated compounds has proven to be a useful method for location of the double bond in some alkenyl compounds 2–7. The double bond of the alkenes can be located since the DMDS adds across the double bond, and cleavage of the carbon‐carbon bond between the adjacent carbons carrying the methyl sulfide (SCH 3 ) substituents leads to two diagnostic ions (GF + , GA + ).…”

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A method for the identification of the double‐bond position of isomeric linear tetradecenols and related compounds based on mass spectra of dimethyl disulfide derivatives

Yuan

Yan

2001

Rapid Comm Mass Spectrometry

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A simple method is presented for calculation of the double-bond position in linear tetradecenols based on mass spectral data of dimethyl disulfide derivatives. In this approach, the m/z ratios of the molecular ion and of one (or both) of the two most abundant fragment ions were utilized to calculate the double-bond position, without the requirement to identify both fragment ions resulting from carbon-carbon cleavage across what was originally the double bond. The approach was tested with mass spectra of dimethyl disulfide derivatives of 12 isomeric tetradecenols, and the double-bond position in each isomer was successfully identified by this method. The method was shown to work also for the corresponding acetates.

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Determination of positions of double bonds in di‐unsaturated esters and a di‐substituted γ lactone by means of GC/MS of dimethyl disulfide derivatives

Cited by 11 publications

References 8 publications

Determination of Double Bond Positions in Triunsaturated Compounds by Means of Gas Chromatography/Mass Spectrometry of Dimethyl Disulfide Derivatives

Determination of Double Bond Positions in Triunsaturated Compounds by Means of Gas Chromatography/Mass Spectrometry of Dimethyl Disulfide Derivatives

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

A method for the identification of the double‐bond position of isomeric linear tetradecenols and related compounds based on mass spectra of dimethyl disulfide derivatives

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