The Effect of Pressure on Organic Reactions

Klärner, Frank‐Gerrit; Wurche, Frank

doi:10.1002/1521-3897(200009)342:7<609::aid-prac609>3.3.co;2-q

Cited by 7 publications

(6 citation statements)

References 34 publications

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“…The high-pressure (10 kbar, 1 bar = 10 5 Pa) reaction [18] between the dibromide 11 and the dicationic precursor 12·2 PF 6 in dimethylformamide (DMF) at room temperature followed by counterion exchange yielded a green solid, which was found to consist mainly of the desired self-complexed cyclophane 1·4 PF 6 together with a small fraction [19] of the noncomplexed and linear cyclophane 2·4 PF 6 in a combined yield of 27 %. The self-complexed cyclophane 1·4 PF 6 was isolated from the mixture by preparative thin-layer chromatography (PTLC) using acetone (Me 2 CO)/NH 4 PF 6 (100:1 v/w) as the eluent.…”

Section: Synthesismentioning

confidence: 99%

Using Molecular Force to Overcome Steric Barriers in a Springlike Molecular Ouroboros**

Nygaard

Liu

Stein

et al. 2007

Adv Funct Materials

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A mechanically interlocked and self‐complexing molecular ouroboros that incorporates the π‐electron‐rich monopyrrolotetrathiafulvalene (MPTTF) unit and the π‐electron‐poor tetracationic macrocycle cyclobis(paraquat‐p‐phenylene) (CBPQT4+) has been synthesized and characterized. The molecular ouroboros constitutes an interesting class of redox‐active interlocked molecules that is structurally similar to the image of the Serpent biting its own tail, whereas, and towards advanced functionality, its mode of action resembles a wound spring. Electrochemical methods and short timescale UV‐vis‐NIR (NIR: near IR) chemical switching experiments verified the reversible oxidation and reduction of the molecular ouroboros akin to the build‐up and release of tension in a spring. Building out from this concept, it was determined by the time evolution of the 1H NMR and UV‐vis‐NIR spectra, however, that the initially interlocked molecular ouroboros is converted into a linear non‐interlocked state by the employment of an appropriate oxidation–reduction cycle. The oxidation‐induced dethreading process occurs when the dicationic MPTTF2+ unit is kept within close proximity to the CBPQT4+ ring by the circular interlocked structure in order to maintain the electrostatic repulsive force between the MPTTF2+ unit and the CBPQT4+ ring for longer periods of time. The resulting high‐energy, and now tightly wound, interlocked conformation overcomes a steric barrier in many minutes, relaxing thermodynamically to form the lowest‐energy linear state in an irreversible process that would otherwise be kinetically improbable without the oxidation.

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Section: Synthesismentioning

confidence: 99%

Using Molecular Force to Overcome Steric Barriers in a Springlike Molecular Ouroboros**

Nygaard

Liu

Stein

et al. 2007

Adv Funct Materials

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“…This effect can often lead to significant reductions in system volume. 9 Thus the solvent and pressure effects may complicate the task of computational modeling. We continue, however, to seek computational methods to address this.…”

mentioning

confidence: 99%

Nucleophilic Ring Opening of Cyclopropane Hemimalonates Using Internal Brønsted Acid Activation

Emmett

Kerr

2011

Org. Lett.

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The reaction of cyclopropanes, geminally disubstituted with one carboalkoxy and one carbohydroxy group, undergoes ring-opening reactions with indole nucleophiles under catalyst-free, hyperbaric (13 kbar) conditions. An internal hydrogen bond is postulated as the mode of activation obviating the need for the Lewis acid catalyst normally used for such donor-acceptor cyclopropane chemistry. These conditions avoid decarboxylation and yield useful adducts with the carboxylic acid group intact for further elaboration.

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“…Another parameter may also be used, the packing coefficient h, defined as the ratio between the Van der Waals and molar volumes. 65 Despite empirical methods to determine the Van der Waals volumes, 66 these approximations are not possible for transition states, so that h is less accessible, since it has to be determined from molecular mechanics or quantum mechanical calculations.…”

Section: Case D Late Transition State With Electrostrictionmentioning

confidence: 99%

Correlation between pressure and steric interactions in organic reactions

Jenner

2005

Tetrahedron

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The Effect of Pressure on Organic Reactions

Cited by 7 publications

References 34 publications

Using Molecular Force to Overcome Steric Barriers in a Springlike Molecular Ouroboros**

Using Molecular Force to Overcome Steric Barriers in a Springlike Molecular Ouroboros**

Nucleophilic Ring Opening of Cyclopropane Hemimalonates Using Internal Brønsted Acid Activation

Correlation between pressure and steric interactions in organic reactions

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