Pressure and phase dependence of the stereochemical course in hot tritium for hydrogen and chlorine-38 for chlorine substitution in meso- and rac-1,2-dichloro-1,2-difluoroethane

Journal Article · Thu Mar 28 04:00:00 EDT 1974 · J. Phys. Chem., v. 78, no. 7, pp. 658-662

DOI:https://doi.org/10.1002/chin.197423145· OSTI ID:4321334

Machulla, H J; Stocklin, G

The pressure dependence of the stereochemical course in hot homolytic T- for-H and /sup 38/ Cl-for-Cl substitution in mesoand rac-1,2-dichloro-l,2- difluoroethane has been studied from 10 to 10/sup 4/ Torr. Distinct differences are observed between the yield vs. density dependence of the retained and the inverted product. For both recoil tritium and chlorine, substitution with inversion of configuration is almost negligible in the gas phase and its yields remained constant over the entire pressure range studied. Typical pressure effects are observed, however, for substitution with retention of configuration, particularly for recoil chlorine. While the change from the high-pressure gas phase to the liquid leaves T-for-H substitution almost unaffected, /sup 38/Cl-for- Cl substitution exhibits a strong phase effect. The absolute yields of the retained product increase by a factor of 2.5, that of the invented product by about 20, almost identical in both diastereomeric substrates. The density dependence of the HCl and HF elimination products is also different for recoil tritium and chlorine; in the latter case the yields follow the increasing trend observed for substitution. While for recoil tritium the predominant substitution channel seems to be a direct replacement with retention of configuration, even in the liquid phase, /sup 38/Cl-for-Cl substitution at higher densities cannot be satisfactorily explained on the basis of the impact model nor by caged radical combination. Alternatively, substitution via a caged complex is discussed. (auth)

• Research Organization: Kernforschungsanlage, Juelich, Ger.
• NSA Number: NSA-29-026698
• OSTI ID: 4321334
• Journal Information: J. Phys. Chem., v. 78, no. 7, pp. 658-662, Journal Name: J. Phys. Chem., v. 78, no. 7, pp. 658-662; ISSN JPCHA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*CHLORINATED ALIPHATIC HYDROCARBONS-- HOT ATOM CHEMISTRY
*CHLORINE 38-- HOT ATOM CHEMISTRY
*FLUORINATED ALIPHATIC HYDROCARBONS-- HOT ATOM CHEMISTRY
*ORGANIC CHLORINE COMPOUNDS-- HOT ATOM CHEMISTRY
*ORGANIC FLUORINE COMPOUNDS-- HOT ATOM CHEMISTRY
*TRITIUM-- HOT ATOM CHEMISTRY
FLUORINATED ALIPHATIC HYDROCARBONS
GAMMA RADIATION
GASES
LIQUIDS
N40410* --Chemistry--Radiochemistry & Nuclear Chemistry--Hot Atom Chemistry
NEUTRON BEAMS
PRESSURE DEPENDENCE
RECOILS
STEREOCHEMISTRY CHLORINATED ALIPHATIC HYDROCARBONS