The Dielectric Properties of Symmetrical Long-Chain Secondary Alcohols in the Solid State

1951 ◽  
Vol 4 (2) ◽  
pp. 213 ◽  
Author(s):  
RL Meakins ◽  
RA Sack
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Dielectric Loss ◽  
Low Temperatures ◽  
Room Temperature ◽  
Molecular Chain ◽  
Hydroxyl Groups ◽  
Crystal Formation ◽  
Secondary Alcohols ◽  
Long Chain

Symmetrical long-chain secondary alcohols in the solid state show very high dielectric loss at audio and radio frequencies. This can be explained by the presence of chains of hydroxyl groups linked by hydrogen bonding and capable of reversing their direction. Further evidence of hydrogen bonding is provided by a study of the melting points of the secondary alcohols and related compounds. The amount of dielectric loss depends markedly on the manner of formation of the solid, being smallest for samples formed by recrystallization from solvents at low temperatures and largest for specimens obtained by slow cooling from the melt. The alcohols of molecular chain-lengths of 13, 15,17, and 19 carbon atoms show a considerable decrease of absorption on storing at room temperature. For alcohols of between 23 and 43 carbon atoms the loss is rather smaller with a peak at higher frequencies, but remains more constant in time. These results are interpreted in terms of competing influences of van der Waals forces and hydrogen bonds during crystal formation ; the former, which lead to a structure unsuitable for the formation of hydrogen-bond chains, are predominant at low temperatures, but become more rapidly neutralized by thermal motion, especially for the shorter molecules. The high temperature modification of the lower homologues is unstable at room temperature, and a molecular diffusion process causes the bond chains to break. Dilute systems of secondary alcohols with hydrocarbons or paraffin wax of similar molecular chain-length show very small dielectric loss suggesting a solid solution in which bond chains cannot be formed ; if the paraffin molecules are appreciably longer, the absorption is large and decreases on storing, presumably owing to the presence of a pure alcohol phase. I.

Polymorphism of naphthazarin and its relation to solid-state proton transfer. Neutron and X-ray diffraction studies on naphthazarin C

1985 ◽  
Vol 399 (1817) ◽  
pp. 295-319 ◽  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Model Comparison ◽  
Molecular Model ◽  
Molecular Formula ◽  
X Ray Diffraction ◽  
X Ray

The crystal structure of naphthazarin C has been determined by neutron diffraction at 60 and 300 K (λ ═ 0.895 Å; 1 Å ═ 10 -10 m ═ 10 -1 nm) and X-ray diffraction at 300 K. The space group is Pc at 60 K, but P 2 1 /c at 300 K. There are small but significant differences in cell dimensions at the two temperatures: a ═ 7.664 (7.915), b ═ 7.304 (7.262), c ═ 15.16 (15.284) Å; β ═ 114.60 (114.20)°; Z ═ 4; U ═ 771.6 (801.3) Å 3 (values at 300 K in parentheses). Neutron diffraction shows that the Pc and P 2 1 /c structures are related by an order-disorder transition at 110±1 K. Structure analysis (1771 reflections; R F ═ 0.035; R W ═ 0.036) showed that the hydroxyl hydrogens are largely ordered at 60 K, the appropriate molecular formula being 5, 8-dihydroxy-1, 4-naphthadione. Neutron diffraction measurements at 300 K (1769 reflections; R F ═ 0.052) indicated a disordered molecular model with one-half of an hydrogen atom attached to each oxygen. X -ray diffraction measurements on naphthazarin C at 300 K (two independent sets of intensity measurements, one with CuKα and the other with MoKα) support this disordered model. The molecular dimensions for naphthazarin A and B also fit this model. Comparison of the crystal structure of naphthazarin C with those of the A and B polymorphs shows that only the former has intermolecular O─H • • • O hydrogen bonding. The diffraction results combined with the available solid-state n. m. r. data show that there is at room temperature a rapid intramolecular exchange of hydroxylic protons between each pair of oxygen atoms in all three naphthazarin polymorphs. Many 1, 3-diketones exist in an enol form in the solid. These enol forms have been reported to be disordered for about twenty molecules at room temperature (this total includes one molecule studied at 108 K, and four amino-imino systems) and ordered systems have been reported for about fifteen molecules. Intermolecular hydrogen bonding occurs only in a few of these crystals.

Temperature Dependence of the Dielectric Properties of Long-Chain Aliphatic Alcohols in the Solid State

1952 ◽  
Vol 5 (4) ◽  
pp. 661 ◽  
Author(s):  
JS Dryden
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Temperature Dependence ◽  
Aliphatic Alcohols ◽  
Experimental Results ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Dielectric Absorption ◽  
Apparent Activation Energies ◽  
Long Chain

The dielectric properties of three primary and three secondary long-chain aliphatic alcohols have been investigated within the temperature range of -20 to 70 �C. The experimental results are discussed in relation to the theory of Sack on dielectric absorption in linear polar chains and to the conclusions reached in earlier papers on the dielectric properties of these compounds. The apparent activation energies in the primary alcohols are approximately three times those in the secondary alcohols. This indicates either different mechanisms of absorption in the two types of alcohols or, if the mechanisms are the same, significant differences in the energy barriers involved.

scholarly journals PHOTODYNAMIC HEMOLYSIS AT LOW TEMPERATURES

1954 ◽  
Vol 37 (3) ◽  
pp. 301-311 ◽  
Author(s):  
Harold F. Blum ◽  
Elizabeth Flagler Kauzmann
Keyword(s):  
Solid State ◽  
Low Temperatures ◽  
Room Temperature ◽  
Photosensitized Oxidation ◽  
Higher Temperature ◽  
Semi Solid ◽  
Lower Temperature ◽  
Dye Molecule

It is shown that photodynamic hemolysis may occur at –79°C. if the erythrocytes are suspended in a solution containing 70 per cent glycerol which prevents hemolysis by freezing; but that there is no hemolysis under the same conditions at –210°C. At the higher temperature the viscosity of the solution is still low enough to permit appreciable movement of molecules, whereas at the lower temperature the molecules must be virtually immobile. The findings are compatible with the idea that the dye molecule acts in a cycle, bringing about successive oxidations by O2 molecules, as has been shown for photodynamic hemolysis at room temperature. The assumption of a combination between dye, O2, and substrate does not explain photosensitized hemolysis in the semi-solid state. The mechanism of photosensitized oxidation by O2 is discussed.

The Dielectric Properties of a Series of dl-n-Eicosanols

1951 ◽  
Vol 4 (3) ◽  
pp. 359
Author(s):  
RJ Meakins ◽  
HK Welsh
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Polar Compounds ◽  
Carbon Chain ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Polar Group ◽  
Dielectric Absorption ◽  
Ready Availability ◽  
Long Chain

Initial investigations of the dielectric properties of normal long-chain secondary alcohols were made with the symmetrical compounds because of their ready availability. The properties of long-chain polar compounds are known to vary considerably, however, with the position of the polar group in the carbon chain and it therefore seemed desirable to make dielectric measurements with some unsymmetrical alcohols. The present paper describes such an investigation of a series of dl-n-eicosanols having the hydroxyl groups in the 2-, 4-, 6-, 8-, and 10-positions, respectively. The results for the melted forms show that slight asymmetry, as in the 10-compound, has little effect on the dielectric properties, but with the more unsymmetrical 4-, 6-, and 8-compounds a considerable enhancement of the dielectric absorption is observed. This is accompanied by increased dispersion of the dielectric constant which, for the 8-compound, reaches a low frequency value of 15. Both ε" and ε' decrease during storage at room temperature. Anomalous results are obtained with dl-n-eicosan-2-ol, probably due to the molecules in the crystal lattice being alternately reversed, end-to-end. As with the symmetrical secondary alcohols, the recrystallized forms give comparatively little dielectric absorption.

Silica-bonded S-sulfonic acid as a recyclable catalyst for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS)

2010 ◽  
Vol 88 (2) ◽  
pp. 164-171 ◽  
Author(s):  
Khodabakhsh Niknam ◽  
Dariush Saberi ◽  
Hajar Molaee ◽  
Mohammad Ali Zolfigol
Keyword(s):  
Sulfonic Acid ◽  
Room Temperature ◽  
Reaction Times ◽  
Chlorosulfonic Acid ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Mild Conditions ◽  
Trimethylsilyl Ethers ◽  
Phenolic Hydroxyl Groups ◽  
Good Range

Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in tert-butylmethyl ether, and used as a catalyst for the silylation of hydroxyl groups. A good range of primary, secondary alcohols and phenolic hydroxyl groups were effectively converted into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of SBSSA under mild conditions at room temperature with short reaction times and in good-to-excellent yields. An excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups was also observed. The heterogeneous catalyst was recycled for 30 runs upon the reaction of benzyl alcohol with HMDS without lossing its catalytic activity.

Synthesis, Structure and Photoluminescence of a Potential Luminescent Material of Mn(II) Coordination Polymer

2012 ◽  
Vol 528 ◽  
pp. 206-209 ◽  
Author(s):  
Xiu Ling Zhang ◽  
Kai Cheng ◽  
Yu Lan Song
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Coordination Polymer ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Room Temperature ◽  
Luminescent Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
1D Chain

A new coordination polymer [Mn3(IP)(4,4'-obb)3]n (1) (4,4'-obb = 4,4'-Oxybisbenzoic acid, IP = 1H-imidazo[4,5-f][1,10]-phenanthroline) was synthesized and characterized by IR, elemental analysis and X-ray diffraction. Single-crystal X-ray analyses revealed that the compound demonstrates 1D structure in which the Mn2+ centers are connected via 4,4'-obb anions into 1D chain, the chains are further connected via hydrogen - bonding and π ••• π interactions. In addition, the photoluminescence for compound 1 is also investigated in the solid state at room temperature.

The Dielectric Properties of Crystalline Long-Chain n-Primary Alcohols at Low Frequencies

1951 ◽  
Vol 4 (3) ◽  
pp. 365
Author(s):  
RJ Meakins ◽  
JW Mulley
Keyword(s):  
Dielectric Properties ◽  
Primary Alcohol ◽  
Dielectric Constants ◽  
Double Layers ◽  
Significant Feature ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Dielectric Absorption ◽  
Long Chain

In a previous paper it was reported that certain crystalline forms of long-chain secondary alcohols show abnormally large dielectric absorption and dispersion of the dielectric constant at audio and radio frequencies. The present paper describes an extension of the investigation to n-primary alcohols and discusses the results in terms of the previously suggested theory of dielectric absorption due to the presence of hydrogen-bonded chains of hydroxyl groups. The most significant feature of the results is that the absorption is larger and occurs at much lower frequencies than for the secondary alcohols. This is considered to be due to the end-to-end arrangement of the molecules in n-primary alcohol crystals, which gives double layers of hydroxyl groups and enables the formation of more extensive hydrogen-bond chains. The dielectric constants at the lowest frequencies are almost as large as those previously reported by Hoffmann and Smyth (1949) for the " waxy " forms of n-primary alcohols. Further aspects described are the changes in dielectric properties during storage, the differences between the melted and recrystallized forms, and the effect of dispersing the molecules in an inert solid solvent. In each of these aspects the observed behaviour is similar to that previously reported for the secondary alcohols.

scholarly journals Is There Water Ice in the Lunar Polar Craters?

2020 ◽  
Author(s):  
Tianxi Sun
Keyword(s):  
Solar Wind ◽  
Solid State ◽  
Hydroxyl Radicals ◽  
Low Temperatures ◽  
Hydroxyl Groups ◽  
The Moon ◽  
Water Ice ◽  
Spectral Identity ◽  
The One

This literature review found that it is doubtful that there is water ice in the polar craters on the Moon. In the course of this review, the following findings were found: (1) The absorption strength of hydroxyl radicals and hydroxyl groups are all 2.9μm, so it is easy to confuse hydroxyl radicals and hydroxyl groups when interpreting M3 spectra data. I do not doubt the ability of LCROSS to detect OH from water, but only suspect that LCROSS is unable to distinguish between hydroxyl radicals from water ice and hydroxyl groups from Moon's methanol due to ignore their spectral identity; (2) The water brought by comets and asteroids and the one caused by solar wind has been exhausted by reacts with the widespread methanol on the Moon in the presence of Pt/α-MoC or Pt/C catalysts. These reacts form large amount of hydrogen, thus clarifying a question NASA raised that "Scientists have long speculated about the source of vast quantities of hydrogen that have been observed at the lunar poles"; (3) The vast quantities of hydrogen in lunar polar craters at extremely low temperatures might be in liquid or solid state now, easy to confuse with water ice. It seems that all our previous misconceptions about water ice in the lunar polar craters might be due to the neglect of the widespread chemical role of lunar methanol. It is necessary to conduct in-depth research in this field in the future.

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