Search

Crystals of the AgNO3-trans-cyclodecene adduct are orthorhombic, a = 5,47, b = 14,69, c = 26,73 A, space group Pbcn, with 4 formula units AgNO3·(C10H18)2 in the unit cell. The structure has been solved by the heavy-atom method and refined by full-matrix least-squares analysis of three-dimensional intensity data. The conformation of the trans-cyclodecene molecule has features in common with that of the cyclodecane ring, but the trans double bond is twisted about 40° from planarity. This deformation must contribute substantially to the strain-energy of trans-cyclodecene. The dependence of the twist-energy on the twist-angle is discussed.

The products isolated from the HOFMANN degradation of trans and cis 1,6-bis-trimethylammonio-cyclodecane (1a) depend on the reaction temperature. When carried out below 100° or when WITTIG'S low-temperature modification, i.e. with KNH2 in liquid ammonia, is employed, cyclodeca-l,5- and -1,6-dienes are formed almost exclusively, as shown by their hydrogenation to cyclodecane. When heated above 70° cyclodeca-l,5-diene (2) undergoes valency isomerisation to 1,2-divinylcyclohexane (4). This compound is obtained directly in ca. 45% yield besides 46% of non-isomerisable cyclodeca-l,5- and -1,6-dienes when the HOFMANN elimination is carried out at 120–150°. In addition, ca. 9% of octalines are formed by a transannular elimination reaction. The COPE elimination reaction of the bis-N-oxide of trans and cis 1,6-bis-dimethylarnino-cyclodecane (1c) at 120–150° affords a similar mixture of products containing ca. 43% of 1,2-divinylcyclohexane. The ease with which cyclodeca-l,5-diene undergoes valency isomerisation is attributed to the concomitant relief of strain and to the proximity of carbon atoms 1 and 6 in the trans/trans isomer.

The results of the X-ray analysis of 1,1,5,5-tetramethylcyclodecane-8-carboxylic acid do not correspond to a reasonable molecular structure. When used as a startingpoint for a strain-energy minimization calculation based on semi-empirical potential functions, they lead to two new conformations for the cyclodecane ring. It is shown that the X-ray results can be explained by assuming that the crystal consists of a random mixture of these two conformations.

1,6-trans-diaminocyclodecane dihydrochloride crystallizes in triclinic and monoclinic modifications. The structure of the triclinic form with a = 9,02; b = 6,19; c = 6,20 A; α = 96,7°; β = 99,3°; γ = 108,1°; space group P1; Z = 1, has been determined by analysis of the (001) and (010) projections and the conformation of the cyclodecane ring thereby established. Although the molecule, and its environment, is crystallographically only centrosymmetric, the carbon skeleton does not deviate significantly from the higher 2/m (C2h) symmetry. Of the torsion angles around the ring, 8 are close to 60° (syn-skew) the remaining 2 being 156° (nearly anti-planar). Some stereochemical implications of the cyclodecane conformation are briefly mentioned.

Degradation of the N-oxides and quaternary salts of the cis and trans forms of 1,6-bis-dimethylamino-cyclodeca-3,8-dienes (4 b) and (4 c), respectively, afforded mixtures of hydrocarbons C10H12 separable by gas chromatography after hydro-genation. In both cases a mixture of decalins, n-butykyclohexane,n-butylbenzene, cyclodecane and an unidentified tricyclic hydrocarbon C10H16 were obtained. However, COPE elimination yielded mainly trans-decalin (66%), HOFMANN elimination mainly the cis isomer (58-74%).

Crystals of 6-ketononanolide (oxacyclodeca-2,6-dione) are orthorhombic, a = 8.886, b = 16.407, c = 11.965 A, space group Pbca, with 8 molecules in the unit cell. The structure has been solved with the help of direct methods and refined by full-matrix least-squares analysis of three-dimensional intensity data. The conformation of the ring is similar to that previously observed in several cyclodecane derivatives, with the ring oxygen and carbonyl groups so situated as to minimize the number of transannular H … H contacts. Evidence for transannular O(ether) … C(carbonyl) donor-acceptor attraction is discussed.

The following vibrational spectra of cyclodecane have been investigated: (1) the IR.-spectrum of the liquid between 1500 and 450 cm−1 at room temperature; (2) the IR.-spectra of the solid in the surroundings of the melting point and at − 70 and − 170° C in the frequency range 1500…650 cm−1; (3) the Raman-spectrum of the liquid from 1500 to 300 cm−1 at room temperature.

Crystals of 1,1,5,5-tetramethylcyclodecane-8-carboxylic acid are monoclinic, a = 9.22 A, b = 14.81 A, c = 11.58 A, β = 111° 0′, space group P21/c with 4 molecules in the unit cell. The structure has been solved by direct methods and refined by full-matrix least-squares analysis of three-dimensional intensitiy data. The conformation of the ring differs from the previously observed cyclodecane conformation, but the detailed results are abnormal in a number of ways (extremely short CC bond lengths, wide CCC bond angles, large temperature factors). The possibility is discussed that the crystal structure is disordered.

Crystals of 1,6-trans-dibromcyclodecane are monoclinic, a = 7,94, b =5,65, c = 12,78 A, β = 106° 47′, space group P2, lc. The unit cell contains two centrosymmetric molecules. The crystal structure has been determined by analysis of the three prin- cipal projections. The ring skeleton has the same conformation as that found in all previously studied cyclodecane compounds, with the substituents in (IIe, IIe) positions.

1,1,6,6-Tetramethyl-cyclodecane and various of its derivatives have been synthesized. The influence of geminal methyl groups on the properties of cyclodecane derivatives, especially on their n.m.r. spectra, has been investigated.