Molecular structure of cyclododecane, C12H24, as determined by electron diffraction and molecular mechanics

Атавин, Е. Г.; Mastryukov, V. S.; Allinger, Norman L.; Almenningen, A.; Seip, Ragnhild

doi:10.1016/0022-2860(89)85069-0

Cited by 22 publications

(13 citation statements)

References 28 publications

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“…70), with other conformations being considerably higher in energy. That is supported by both experimental results [44] and theoretical calculations [18,45]. Thus, considering cycloalkanes in the order of increasing ring size, this is the first case since cyclohexane that a single low-energy conformation can be assigned to a cycloalkane.…”

Section: Large Ringssupporting

confidence: 55%

Conformational analysis of cycloalkanes

Dragojlović

2015

ChemTexts

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Conformational analysis is a comparatively new area of organic chemistry that has been developed well after the theories of organic reactions, bonding in organic compounds and stereochemistry. It was only in the second half of twentieth century that its importance was fully recognized and its central role with respect to bonding, reactivity and stability of organic compounds was appreciated. Fundamental concepts of conformational analysis, a deeper discussion of the conformational analysis of small and common rings and an introduction into the conformational analysis of medium and large rings are presented at a level suitable for an introductory organic chemistry course. This discussion aims to provide a better understanding of the complex relationship among different types of strain, while also discussing the factors that determine stability of a particular conformation. Finally, the unique nature of each class of cycloalkanes is explored.

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Section: Large Ringssupporting

confidence: 55%

Conformational analysis of cycloalkanes

Dragojlović

2015

ChemTexts

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“…The observed ring conformation is in agreement with that reported previously for the Ac 12 c residue [31]. This 12membered ring conformation, which is described as [3,3,3,3] according to Dale's nomenclature [46], was characterized in the crystal and electron diffraction studies of cyclododecane [47,48] and is the global minimum structure in the energy calculations of 12-membered rings [49,50]. A recent report on the cyclododecane conformation in crystal state also identified [3,3,3,3] as the sole conformer observed in crystalline state, so far [51].…”

Section: Resultssupporting

confidence: 90%

Crystal structure of a tripeptide containing aminocyclododecane carboxylic acid: a supramolecular twisted parallel β-sheet in crystals

2016

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The crystal structure of a tripeptide Boc-Leu-Val-Ac12 c-OMe (1) is determined, which incorporates a bulky 1-aminocyclododecane-1-carboxylic acid (Ac12 c) side chain. The peptide adopts a semi-extended backbone conformation for Leu and Val residues, while the backbone torsion angles of the C(α,α) -dialkylated residue Ac12 c are in the helical region of the Ramachandran map. The molecular packing of 1 revealed a unique supramolecular twisted parallel β-sheet coiling into a helical architecture in crystals, with the bulky hydrophobic Ac12 c side chains projecting outward the helical column. This arrangement resembles the packing of peptide helices in crystal structures. Although short oligopeptides often assemble as parallel or anti-parallel β-sheet in crystals, twisted or helical β-sheet formation has been observed in a few examples of dipeptide crystal structures. Peptide 1 presents the first example of a tripeptide showing twisted β-sheet assembly in crystals.

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“…N s values for the 4-and 6-spacer cyclic gemini surfactants were estimated in this work by calculating the volume (v = 0.310 nm 3 /ring) of a cyclododecyl tail (in the micellar phase) from the experimentally determined post-micellar apparent molar volume data using the aforementioned additivity method to subtract out the contribution from the head group. The diameter of the cyclododecyl group (equivalent to l) has been determined from electron diffraction experiments to be 0.554 nm (46). Using the head group areas in Table 2 at 42…”

Section: Resultsmentioning

confidence: 99%