1012. The isomeric pentane-2,4-diol cyclic sulphites

Lauterbur, Paul C.; Pritchard, Jane; Vollmer, R.

doi:10.1039/jr9630005307

Cited by 28 publications

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“…1,2 Pritchard and coworkers 3,4 isolated both geometric isomers of meso-2,4-pentanediol cyclic sulfite and found that the stretching S=O occurs at 1190 cm À1 for an axial orientation of this group, whereas in the equatorial isomer such stretching is at ca 1230 cm…”

Section: Introductionmentioning

confidence: 97%

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Ab initio study of the conformational equilibrium of trimethylene cyclic sulfite

Contreras

Madariaga

2000

J. Phys. Org. Chem.

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Ab initio calculations, in the frame of MO theory, were carried out on both most stable (chair) conformers of trimethylene cyclic sulfite. Optimized geometries derived at the HF/6-31G* level reveal that both conformers possess a rigid chair conformation with the S=O group located either axially (conformer I) or equatorially (conformer II). Energy calculations at the MP2/6-311G**//HF/6-31G* level indicates that conformer I is ca 4.6 kcal mol À1 more stable than II. The I II interconversion was studied in the gas phase at different temperatures and in solutions of low-and high-polarity solvents. The calculations reveal that in the gas phase and in solutions of low-polarity solvents the conversion of I into II does not occur. In medium-high-polarity solvents, such as acetonitrile and dimethyl sulfoxide, II is present at ca 12%.

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Section: Introductionmentioning

confidence: 97%

“…The IR bands due to the #(S=O) modes of TCS conformers in several solvents are given in Table 4. According to Table 4, in the IR spectra of TCS in the gas phase and in CCl 4 and CS 2 solutions, just one band at ca 1190 cm À1 should be detected. In polar solvents, such as acetonitrile and dimethyl sulfoxide, a shoulder at ca 1230 cm À1 is also observed.…”

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confidence: 98%

Ab initio study of the conformational equilibrium of trimethylene cyclic sulfite

Contreras

Madariaga

2000

J. Phys. Org. Chem.

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“…From dipole moment, infrared and NMR data, concerning propane-1.3-diol sulfite and a number of model compounds, it was demonstrated that propane-1.3-diol sulfite exists in the rigid chair conformation with the S=O bond axial [3). Last year van Woerden andHavinga [6] established that the stretching frequency of an axial S=O in a six-membered cyclic sulfite occurs at 1190 ± 5 em -I and is independent of solvent or structural changes [4]. Similarly an equatorial 8=0 in a six-membered cyclic sulfite gives rise to a peak at 1230 cm -I.…”

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confidence: 99%

NMR and Mass Spectra of Conformational Isomers of 2‐Methylpentane‐2,4‐Diol Sulfite

Sarel¹,

Usieli²

1968

Israel Journal of Chemistry

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From the ester exchange reaction between 2-methylpentane-2.4-diol and dimethyl sulfite, two isomeric cyclic sulfites were isolated in a 3 to 2 ratio. On the basis of IR and NMR data it was concluded that the isomers exist in the rigid chair conformation and the isomerism springs from the pyramidal S=O orientation. An axial S=O is assigned to the liquid isomer (predominant) and an equatorial S=O to the solid compound (minor). The 25 ev mass spectra of the two isomers at room temperature is herein described.[1-6]. Of particular interest in this context is the isolation of two cyclic sulfites of mesopentane-2.4-diol [41, shown to constitute conformational isomers of the structures CH 3 (e) CH3 (e) 5=-0 (a) (I) and CH 3 (e) CH 3 (e)S=O(e) (lI}[51.! is the more stable isomer; it could not be isomerized to II to any measurable extent. By contrast, II could be isomerized completely into I on heating at 200 0 for 15 min. From dipole moment and infrared studies on 2-substituted propane-1.3-diol sulfites, van Woerden and Havinga [61 concluded that the S=O bond in trimethylene sulfites has a preference for the axial conformation, which is 3.5 ± I Kcal/mole more stable than the equatorial one.Unlike the meso form, racemic pentane-2A-diol sulfite could not be separated into geometric isomers, viz, into CH 3(e) CH 3(a) s=o (e) (III) and CH 3(a} CH 3(e) S=O (a) (IV). It comprises a mixture of both conformational isomers, already at room temperature, implying that the difference in free energy between III and IV is smaller than between I and II. This may indicate that the CH 3 (a) 5=0 (a) repulsion obliterates, at least partly, stabilization of the S=O bond in the axial conformation [51.t Dedicated to the memory of the Late Aryeh Poles.

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“…The first isomers of trimethylene sulfite substituted in the 4-and 6-positions were isolated by Lauterbur et al (3) who, on the basis of i.r. and n.m.r.…”

Section: Introductionmentioning

confidence: 99%

“…The early literature of trimethylene sulfite and its derivatives is mainly concerned with the orientation of the exocyclic oxygen atom (1)(2)(3)(4)(5)(6), although equilibrium mixtures of conformers are suggested (7,8). The positioning of the exocyclic oxygen has since been shown to be axial in solution studies (9)(10)(11)(12) in X-ray diffraction of solid crystals (13,14), and in the gas phase by electron diffraction (1 5 ) .…”

Section: Introductionmentioning

confidence: 99%

The Conformation of Racemic 4,6-Dimethyl Trimethylene Sulfite by Gas Phase Electron Diffraction

Mustoe¹,

Hencher²

1972

Can. J. Chem.

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The molecular geometry of the racemate rrcrr1~-4,6-dirnethyl trimethylene sulfite has been studied in the gas phase by electron diffraction. Six trial conformations were examined by least squares fitting of the intensity data. A significance test applied to the fits obtained for each of the six static models tested indicate that the best single representation of the molecule has a chair conformation, although a mixture containing other conformations could not be definitely eliminated. It was not possible to conclusively discriminate between an axial or an equatorial S==O bond, although the axial position is favored. La geometrie moleculaire du rrarls dimethyl-4,6 trimethylene sulfite racemique a Cte etudiee en phase gazeuse par diffraction electronique. Six conformations ont ete testees par la methode des ajustements aux moindres carres sur les donnees des intensites. Un test significatif applique aux ajustements obtenus sur chacun des six modeles statiques montre que I'unique et la meilleure representation de la molecule possede une conformation chaise, bien qu'un melange d'autres types de conformations n'ait pu Ctre ecarte definitivement.

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1012. The isomeric pentane-2,4-diol cyclic sulphites

Cited by 28 publications

References 0 publications

Ab initio study of the conformational equilibrium of trimethylene cyclic sulfite

Ab initio study of the conformational equilibrium of trimethylene cyclic sulfite

NMR and Mass Spectra of Conformational Isomers of 2‐Methylpentane‐2,4‐Diol Sulfite

The Conformation of Racemic 4,6-Dimethyl Trimethylene Sulfite by Gas Phase Electron Diffraction

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