Röntgenuntersuchungen an natürlichen Kohlen

Schoon, Th.

doi:10.1002/ange.19380513603

Cited by 12 publications

(5 citation statements)

References 8 publications

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“…A similar layer packing and electron diffraction pattern have been found for cetyl palmitate (hexadecyl hexadecanoate). 23,24 In earlier electron diffraction studies of this ether, 23 a ) 5.64 and b ) 7.43 Å, in accord with results of this study. Also in agreement with earlier work, 23 the crystal habits were poorly defined.…”

Section: Resultssupporting

confidence: 93%

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Internal Heteroatom Substitution and the Layer Packing of Polymethylene Chains

Dorset¹,

and²,

Snyder³

1999

J. Phys. Chem. B

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In an investigation of methylene replacement by small heteroatom insertions the crystal structures of N,Ndioctadecylamine, (C 18 H 37 ) 2 NH, and dihexadecyl ether, (C 16 H 33 ) 2 O, were determined by electron crystallography and infrared spectroscopy. Crystals of the amine, epitaxially oriented on naphthalene, are characteristic of the analogous odd-chain n-paraffin in its high-energy orthorhombic B-polymorph. Cell constants are a ) 7.52-(2), b ) 5.04(1), and c/2 ) 50.0(4) Å and the extinction rules for the 0,k,l reflections (k + l ) 2n + 1) are consistent with the space group A2 1 am. Carbon and nitrogen coordinates in a paraffin-like model match observed data reasonably well (R ) 0.22). A binary phase diagram reveals that the secondary amine is continuously cosoluble with the n-paraffin of the same chain length (n-C 37 H 76 ). The ether, crystallized on benzoic acid, is polymorphic. The major monoclinic form, which forms a eutectic solid with n-C 33 H 68 , crystallizes in space group Aa with a ≈ 5.59, b ≈ 7.40, and c ) 88.66 Å and ) 116.2°. Its projected crystal structure includes a twisted chain conformation in an oblique layer (R ) 0.26). The orthorhombic form in space group A2 1 am (c/2 ) 45.1 Å) resembles the odd-chain paraffin and may be continuously co-soluble with it.

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Section: Resultssupporting

confidence: 93%

“…23,24 In earlier electron diffraction studies of this ether, 23 a ) 5.64 and b ) 7.43 Å, in accord with results of this study. Also in agreement with earlier work, 23 the crystal habits were poorly defined. There was also evidence for a second rectangular layer packing for this material from h,k,0 patterns resembling Figure 1a.…”

Section: Resultssupporting

confidence: 93%

Internal Heteroatom Substitution and the Layer Packing of Polymethylene Chains

Dorset¹,

and²,

Snyder³

1999

J. Phys. Chem. B

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“…The above forms have been studied with some success from th e standpoin t of geometrical packing [11][12][13]. That is, if one considers the molecules to be made up of overlapping spheres of size and separation consistent with atomic l'adii and molecular bond lengths, then the structures one would expect for densest packing are consistent with structures actually observed .…”

Section: Temperatures and Heats Of Phase Changesmentioning

confidence: 93%

An analysis of the solid phase behavior of the normal paraffins

Broadhurst¹

1962

J. RES. NATL. BUR. STAN. SECT. A.

625

381

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A set of best values for t he te mperatures a nd enthalpies of fusion alld transition for the n-paraffins is presented. From a n a nalysis of these data a general qualitative t heory of the phase behavior of the n-paraffins is developed. Four di stinct. crystal structures-h exagonal, t riclinic, monoclinic, and orthorhombic-describe t he solid phases of all n-paraffins with more than nine carbon atoms in the cha in. The la tter t wo structures beco me equivalent at longer chain lengt hs. Odd-even d ifferences are resolved in terms of reasonable diffet'ences in end group packing, a nd t he smooth in crease in melting a nd transition t emperature " 'ith increasing chain length is attributed to a dec rease in t he r atio of end groups to ch ain gro ups. Double t ransitions a re predicted for several pure n-paraffins a bove n-C34H 70 • Impurity effec ts are isolated from the pure n-para ffin properties a nd disc ussed. The equat ion, TM (O K ) = 414.3 (n-1. 5) ! (n + 5.0) is presented as a correct d escript ion of the m elting te mperatures (T M ) of all n-paraffins above n-C44H IlO • Suffi cient data t o p ermit an acc urate extrapolation of the enthalpie and entropies of fu sion to the infinite-c bain limit are not avail a ble.

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“…The geometrical packing of the four crystalline forms described above has received considerable attention in the literatue (Kitaigorodskii, 1957b(Kitaigorodskii, ,c, 1961(Kitaigorodskii, , 1965Kitaigorodskii and Mnyukh, 1959a;Schoon, 1938). These structures do represent the molecular arrangements which on a theoretical basis could be expected to give the densest packing.…”

Section: Crystalline Structure Of Normal Alkanesmentioning

confidence: 99%

Normal Alkanes

Turner¹

1971

Product R&D

167

100

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He holds a B.S. in chemistry from the University of Pennsylvania and is coauthor of several papers dealing with composition, properties, and behavior of petroleum waxes.In addition to waxes his interests include petrochemicals, polymers, and synthetic nutrients. He is a member of the American Chemical Society, the American Association for the Advancement of Science, and the Franklin Institute and a Fellow of the American Institute of Chemists.

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Röntgenuntersuchungen an natürlichen Kohlen

Cited by 12 publications

References 8 publications

Internal Heteroatom Substitution and the Layer Packing of Polymethylene Chains

Internal Heteroatom Substitution and the Layer Packing of Polymethylene Chains

An analysis of the solid phase behavior of the normal paraffins

Normal Alkanes

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