The synthesis and interconversions of the higher homologous enones of bullvalene have recently been described; 9 is clearly inconsistent with the lack of symmetry in the nmr spectrum of 1; see M. J.
Dipole moments are reported for trimethylene sulfite and 11 alkyl derivatives in a variety of solvents (C6H12, CC14, C6H6, dioxan). The variation of dipole moment with solvent for one of the 5-t-butyltrimethylene sulfite isomers is confirmed, but this behavior is not shown by the other compounds. This latter fact is used to rule out rapid chair-chair interconversion for these compounds. Recent ultrasonic absorption experiments are reinterpreted in the context of vicinal electron pair interactions and their effect on conformational analysis of sulfites and similar six-membered compounds. The result is a general scheme which is consistent with available information and which we believe is preferable to analysis of these compounds by analogy with cyclohexane.Onamesure, dans quelques solvants (C6H12, CC14, C6H6, dioxane), les moments polaires du sulfite de trimethylene et de 11 derives alkylts. Nous avons confirme que le moment polaire de I'un des tert-butyl-5 sulfite de trimethylene varie avec le solvant; cette variation n'est pas observte avec les autres composCs. Ce dernier fait est utilisk pour exclure la possibilite d'une interconversion chaise-chaise rapide entre ces composCs. Des rtsultats recents d'absorption ultrasonique sont reinterpretts dans le contexte d'interactions entre des paires d'electrons vicinaux et de leurs effets sur I'analyse conformationnelle des sulfites et des composes cycliques a six chainons de nature similaire. Le resultat est un schtma general qui est consistant avec les informations disponibles et qui, nous le croyons, est preferable k une analyse de ces composts par analogie avec le cyclohexane.
By the low temperature nuclear magnetic resonance integration method the standard free energy difference between the diequatorial and the diaxial forms of I-H,4-H-trans-1,4-di(trifluoroacetoxy)-cyclohexane-d8 was found to be 7 7 + 5 cal/mole. The conformational free energy (-AGO) of the trifluoroacetoxy group in the monosubstituted cyclohexane was 485 1 4 call mole at the same temperature. The non-additivity of the -AGo values is discussed in terms of transannular electrostatic interaction.
Proton n.m.r. chemical shifts and coupling constants are reported for trimethylene sulfite and 10 alkyl derivatives in CC14. Data are discussed in terms of possible chair and non-chair conformations and results arecompared with those from dipole moment studies. The shift reagent Eu(dpm), is used to aid configurational assignments. Conclusions from n.m.r. and dipole moments are consistent and indicate that several of the sulfites exist to a considerable degree in non-chair conformations.Les dbplacements chimiques des protons en r.m.n. et les constantes de couplage sont donntes dans CC14 pour le trimethylene sulfite et pour dix derives alkylts. Les donntes sont discutees en fonction des conformations possibles chaise et non-chaise et les resultats compares a ceux des ttudes de moment dipolaire. Le reactif de deplacement Eu(dpm), est utilisb pour faciliter les assignations de configuration. Les conclusions tirees de la r.m.n. et des moments dipolaires sont importantes et indiquent que plusieurs des sulfites existent pour une part importante sous des conformations non-chaise.
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