The Crystal Structure of the Normal Paraffin Hydrocarbons

Smith, Allan E.

doi:10.1063/1.1698826

Cited by 273 publications

(123 citation statements)

References 6 publications

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“…Inspection of the scattering diagrams confirmed the structure reported by Smith (1953) Approximate intensities of 90 reflexions were obtained by visual estimation from Weissenberg photographs and additionally by measuring the peak areas of powder diagrams (corrected for Lorentz-polarization effects). Only two parameters, the subcell edge c~ along the chain axis and the positional parameter x of the center of one molecule, were varied in a leastsquares analysis.…”

Section: Modification a (T< 545°c)supporting

confidence: 70%

“…Two minor differences are noted when comparing the structure of modification A with that given by Smith (1953) for C23H48. First we found smaller lattice constants (a=7.44, b=4-96 versus a=7.48, b= 4"97 A).…”

Section: Discussionmentioning

confidence: 97%

“…At low temperatures, three different modifications are found: an orthorhombic one if the number of carbon atoms n is odd, and if n is even a triclinic or monoclinic one depending on whether n < 26 or n > 26 respectively. X-ray structure determinations have been carried out for these modifications (Smith, 1953;Mfiller & Lonsdale, 1948;Shearer & Vand, 1956).…”

Section: Introductionmentioning

confidence: 99%

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Packing of paraffin chains in the four stable modifications of n-tritriacontane

Piesczek¹,

Strobl²,

Malzahn³

1974

Acta Crystallogr Sect B

139

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The n-alkane C33H68 exhibits three phase transitions between room temperature and the melting point T,,= 71-8 °C. The modes of chain packing in the four modifications (A,B, C, D) were determined from Weissenberg photographs. Modification A, existing at temperatures <54.5°C, is the known orthorhombic form (space group Pcam) generally found at low temperatures for odd-numbered paraffins. The modifications B and C, which are stable in the temperature ranges 54.5°C< T< 65.5°C and 65.5 °C < T< 68 °C, possess monoclinic unit cells (with space groups Aa and A2 respectively), the crystals being twins. In the high-temperature form D, the so-called 'rotator-phase', the crystalline order is strongly disturbed. Only a few low-order reflexions exist. Their positions in reciprocal space show that the chain axis is tilted from the normal to the end group planes by approximately 19.5 ° . The lateral packing closely approaches a hexagonal form but does not reach it.

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Section: Modification a (T< 545°c)supporting

confidence: 70%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Packing of paraffin chains in the four stable modifications of n-tritriacontane

Piesczek¹,

Strobl²,

Malzahn³

1974

Acta Crystallogr Sect B

139

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“…Such structures should be called A more general question may be asked concerning the conditions necessary for the formation of a polymorph or of a polytype. As has been pointed out by Ubbelohde (1938) and Smith (1953), it seems that 'normal' monoclinic paraffins are obtained in very pure conditions while the 'normal' orthorhombic phases form when the starting product contains about 2% of neighbouring homologues. But this is not the only condition, because the formation of polymorphs and polytypes depends also on the solvent.…”

Section: Discussionmentioning

confidence: 85%

“…According to the crystallization conditions (temperature, nature of the solvent, purity of the products) a given paraffin crystallizes in different polymorphic structures (Holder & Winckler, 1965;Smith, 1953). For this reason we describe exactly the experimental conditions.…”

Section: Experimental Datamentioning

confidence: 99%

Polytypic structures of n-C28H58 (octacosane) and n-C36H74 (hexatriacontane)

Boistelle¹,

Simon²,

Pèpe³

1976

Acta Crystallogr Sect B

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Octacosane (C28H58) and hexatriacontane (C36H74) obtained by crystallization at room temperature from light petroleum solutions are polytypic modifications of the monoclinic structures. Their structure is a stacking of alternate monoclinic layers, related one to the other by a twofold axis perpendicular to the (001) plane. Space group Pbca, Z= 4. Cell parameters a= 7.42, b= 5-59, e= 66.50 or 84.50 ,~ for C28Hs8 and C36H74 respectively. The paraffinic chains are regular with C-C and C-H mean distances of 1.526 and 1 "00 •. The mean C-C-C angle is 113.9 °. Thermal motion is anisotropic, weak in the direction of the chain. Lateral contacts between chains are the same in this structure as in the monoclinic structure.

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Vibrational Spectroscopy of Lipids

Lewis

McElhaney

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Vibrational Spectroscopic Studies of Lipid Phase Transitions Hydrocarbon Chain‐Melting Phase Transitions C  H Stretching Vibrational Modes CH 2 Deformation, CH 2 Wagging and CH 2 Rocking Vibrational Modes Carbon–Carbon Skeletal Vibrational Modes Phase Transitions Involving Nonlamellar Lipid Phases Phase Transitions Involving Crystalline Lipid Phases Structural Characterization of Melted or Liquid‐Crystalline Lipid Phases Estimation of Per‐Chain Conformer Concentrations in Melted Hydrocarbon Chains Estimation of the Mean Lengths of All‐Trans Segments in Lipid Hydrocarbon Chains Distribution of Chain Conformers along Lipid Hydrocarbon Chains Structural Characterization of Crystalline and Quasi‐Crystalline Lipid Phases Lateral Packing of Lipid Hydrocarbon Chains Studies of the Polar–Apolar Interfaces of Lipid Aggregates Interactions between Lipid Polar Headgroups Concluding Remarks Acknowledgments

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The Crystal Structure of the Normal Paraffin Hydrocarbons

Abstract: Articles you may be interested inSurface structures of normal paraffins and cyclohexane monolayers and thin crystals grown on the (111) crystal face of platinum. A lowenergy electron diffraction study

Cited by 273 publications

References 6 publications

Packing of paraffin chains in the four stable modifications of n-tritriacontane

Packing of paraffin chains in the four stable modifications of n-tritriacontane

Polytypic structures of n-C28H58 (octacosane) and n-C36H74 (hexatriacontane)

Vibrational Spectroscopy of Lipids

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