Effects of olefins on the radiolysis of liquid cyclohexane I

Cramer, W. A.; Piet, G. J.

doi:10.1039/tf9676301402

Cited by 12 publications

(3 citation statements)

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“…Thus, the enthalpy change associated with the area under the first peak is only the difference between the enthalpy change involved in the endothermic strand dissociation of poly (A + U) and the AH value corresponding to the exothermic attachment of the released poly U to the duplex poly (A + U). Hence the enthalpy change AH(add) for the "addition" reaction poly (A + U) + poly U = poly (A + 2U) (7) can be calculated from the measured transition enthalpy of poly (A + U) (eq 3) at a conversion temperature equal to the Tc value of the first peak. However, the application of the elementary relationships of thermochemistry requires some comments in this case.…”

Section: The Polynucleotide Systemmentioning

confidence: 99%

Thermodynamic investigation of the helix-coil transitions of a polyribonucleotide system

Neumann¹,

Ackermann²

1969

J. Phys. Chem.

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Some relative thermodynamic state functions of various types of structure which occur in the nucleic acid model system consisting of polyriboadenylic acid (poly A) and polyribouridylic acid (poly U) have been determined using the method of adiabatic calorimetry. Polymer concentrations have been calculated from the content of organic phosphorus of the components of the samples. The content of organic phosphorus has been determined by means of a chemical procedure following the method of Asmus and Baumert (1968). Since poly A is forming an intramolecular secondary structure in the temperature range covered by the calorimetric measurements, the measuyed transition enthalpies have been extrapolated to about 9 5 O , where poly A exists almost entirely in the randomly coiled state. This extrapolation yields the values AHo (A + U) = 9.3 f 0.5 kcal/mol of (A + U) for the helix-random coil transition of the helical duplex poly(A + U), and AHo(A + 2U) = 13.5 =k 0.5 kcal/mol of (A + 2U) for the dissociation of the three-stranded complex poly(A + 2U). The calorimetric procedure (measuring continuously the heat capacity of the polymer solution as a function of temperature) involves the experimental determination of the fraction of structural change. Therefore the thermal helix-coil transition of the double-stranded p01y(~k + U) has been analyzed in terms of current theoretical approaches.Following the calculation procedure of Applequist (1967), the stacking parameter introduced by Crothers and Zimm (1964) is found to have a value of about 400, which is considered to be representative for this doublestranded polyribonucleotide system. Additionally, numerical values of some (average) properties of poly(A + U) at the conversion temperature are given. Appropriate interpolation along measured transition enthalpies yields an approximate value of AHo(A) = 4.5 =t 2 kcal/mol of (A) for the transition of neutral poly A.

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Section: The Polynucleotide Systemmentioning

confidence: 99%

Thermodynamic investigation of the helix-coil transitions of a polyribonucleotide system

Neumann¹,

Ackermann²

1969

J. Phys. Chem.

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“…Effects of N20 and N20 + 02. Nitrous oxide reacts reacts with electrons.8-12 '28•29 HO + e" ->-N2 + O- (23) Nitrogen formation in the presence of N20 is not affected by addition of oxygen, as is shown in Table I. This either suggests that 02 does not compete with N20 for electrons or that 02-transfers its electron to N20.…”

Section: Discussionmentioning

confidence: 84%

“…These olefins may react with various intermediates such as radicals, ions, and exited molecules. 23 The following reactions between radicals and pentene, which is the major unsaturated product in irradiated «-pentane, will be considered…”

Section: Discussionmentioning

confidence: 99%

The radiolysis of liquid pentane

Koch¹,

Houtman²,

Cramer³

1968

J. Am. Chem. Soc.

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4 5 6Both in water and A N m-nitroaniline is a stronger base than the ortho isomer, the difference in their pKdgH+ in A N being 7.6 (present paper) -4.85 = 2.75 units, the same difference as in water. 26 Although o-nitroaniline is a much stronger base than AN, water, and methanol, and therefore a much stronger hydrogen-bond acceptor than AN, no evidence has been obtained that it breaks the hydrogen bond between the donor water and the acceptor AN. (26) M. A. Paul and F.Abstract: The radiation-induced decomposition of liquid n-pentane was studied as a function of temperature and total dose. Effects of olefins, oxygen, and nitrous oxide on product formation were also investigated. At room temperature, rupture between a primary and a secondary carbon atom occurs with a G value of 0.3 and between two secondary carbon atoms with a G value of 1.2. The total yield of C-C rupture was found to be temperature dependent, with G values of 1.7, 1.5, and 1.0 at temperatures of 95, 20, and -1 1 6 O , respectively. Unsaturated products with six to ten C atoms, formed at low doses, are suggested to result from reactions within the spurs. Isomerization of radicals, though occurring, is relatively unimportant. Effects of an increase in radiation dose are attributed to the accumulation of olefins in the irradiated liquid. It is concluded that these olefins not only scavenge radicals and atoms, but that they are also involved in other processes. Similarly, the reduction in hydrogen yield in the presence of pentene is only partly due to scavenging of H atoms. Positive ions probably contribute to polymer formation in these solutions. Effects of oxygen and of nitrous oxide indicate that saturated products are mainly formed in reactions involving free radicals, whereas a considerable fraction of C2-G olefins are produced by molecular elimination. Positive ions are among the intermediates in the formation of these olefins.he radiolysis of liquid n-pentane has been the subcomplete product analysis has been reported at low (8) G . Czapski and J.(31) This interpretation is consistent with observed increases in hydrogen yield when HI or HCl is added to cyclohexane: P. J.Horner and A.

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The influence of the cyclic structure of hydrocarbons on radiation protection

Földiák

Wojnárovits

1972

International Journal for Radiation Physics and Chemistry

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Effects of olefins on the radiolysis of liquid cyclohexane I

Cited by 12 publications

References 1 publication

Thermodynamic investigation of the helix-coil transitions of a polyribonucleotide system

Thermodynamic investigation of the helix-coil transitions of a polyribonucleotide system

The radiolysis of liquid pentane

The influence of the cyclic structure of hydrocarbons on radiation protection

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