1.2- Difluoro benzene

The final geometry optimizations with the DZ+D basis set and the analytic calculation of the force fields and MP-2 corrections were done with the program GRADSCfI on a CRAY-IA. There are 128 basis functions for the difluoro-benzenes, 132 basis functions for the dihydroxybenzenes and 136 basis functions for the diaminobenzenes. The calculations on the difluorobenzenes require about 14 x 10 non-zero 2e integrals whereas the calculations on the diaminobenzenes require about 40 x 10 non-zero 2e integrals. The integral sort step required for the... 

This diamine was prepared from 2,4-dinitro-l,5-difluoro benzene by a catalytic reduction over SnCl /HCl at 50-60oC for 3 hours. The diamine was recrystallized from benzene to yield a white product (mp. 112.5-113°C). ... 

Nonbonded interactions may obtain in halosubstituted benzenes. For example, consider the model compound o/T/io-difluoro-benzene which can exist in either a planar geometry or a distorted geometry in which the C-F bonds are bent, alternately above and below the mean plane as a result of severe dipolar and steric repulsion. 

Less heavily substituted benzenes also undergo photochemical scrambling of the type observed in the vapor phase for the xylenes. Thus 1,4-difluoro benzene irradiated at 2690 A produces solely quantities of the 1,3- and 1,2-isomers.58 Upon irradiation with a less monochromatic light source, the 1,3-isomer gives 1,2 and 1,4, and the 1,2-isomer gives the 1,3 and 1,4, although in these cases there is some polymer formation.58... 

An important improvement with regard to both substrate tolerance and enantioselectivity of the AD was the introduction of the anthraquinone-bridged ligands (DHQ)2AQN and (DHQD)2AQN [2], These ligands are easily accessible fromphthalic anhydride and 1,4-difluoro benzene, and in many aspects their catalytic behavior reflects that of the standard bis-cinchona alkaloids described in Section 6D.1. 

PENTANETHIOL HEXACHLORO-BENZENE HEXAFLUORO-BENZENE O-DICHLORO-BENZENE M-DICHLORO-BENZENE P-DICHLORO-BENZENE M-DIFLUORO-BENZENE O-DIFLUORO-BENZENE P-DIFLUORO-BENZENE BROMOBENZENE CHLOROBENZENE FLUOROBENZENE lODOBENZENE BENZENE PHENOL BENZENETHIOL... 

One-photon excitation studies on the fluorescence decay properties of isolated aniline,24 deuteriated26 and difluoro-benzenes,27 and other simply substituted benzenes28 have been carried out. In the case of aniline, the results quoted by different groups of workers differ markedly. As an example, results for excitation of four transitions populating two levels are given in Table 1. As can be seen from Table 1, the vast difference in results makes discussion of the trends difficult. 

Further work by the same group " aimed to obtain o-diphosphino-benzenes (55) by double nucleophilic aromatic substitutions on o-difluoro-benzene tricarbonylchromium complexes (Scheme 5.24). 

Scott et a/. determined the molar volume at saturation of 1,2-difluoro-benzene (326 to 367 K) and also the pressure coeflicient of heat capacity they deduced values of B . 

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