Octafluoro paracyclophane

The spectroscopic properties (e.g. UV spectra) of the bridge-fluor-inated l,l,2,2,9,9,10,10-octafluoro[2.2]paracyclophane (7) resemble those of other [2.2]paracyclophanes 34h... 

The UV spectra of 4,5,7,8-tetrafluoro[2.2]paracyclophane (26) 18> and of the octafluoro compound 27 54> reveal the close relationship of these compounds to unsubstituted [2.2]paracyclophane (2). The absorption bands occurring between 286 and 291 nm, like those in the spectra of 2 can be attributed to deformation away from planarity of the aromatic rings. Compared with the fluorine-substituted open-chain analogs, these absorption bands are likewise bathochromically shifted by about 25 nm. 

It has been shown that displacement of the iodo substituent in 4-iodo-l,l,2,2,9,9,10, 10-octafluoro[2.2]paracyclophane by arenethiolates or by stabilized enolates occurs by the radical chain. S rn 1 mechanism. The reaction occurs in DMF with photochemical stimulation.4... 

Octafluoro[2.2]paracyclophane is prepared in refluxing tetrahydro-furan (THF) and hexamethylphosphoramide or DMSO solution from 1,4-bis(bromodifluoromethyl)benzene. Trimethylsilyltributyllin is used as a reducing agent. Cesium fluoride as a catalyst gives superior yields (40%) in comparison to potassium fluoride. To favor the formation of rings, the reaction must be accomplished in highly diluted systems. 

Octafluoro[2.2]paracyclophane and dodeca-fluoro[2.2]paracyclophane can be alternatively prepared by the treatment of 1,4-bis(halodifluorometh-yl)benzene with PbBr2/Al in A A -dimethylformamide at room temperature via the a cyclocoupUng reaction. ... 

Parylenes have dielectric constants of 2.35 to 3.15. The dielectric constant decreases as the quantity of fluorine atoms increases within the polymer, therefore, octafluoro[2.2]paracyclophane is a valuable monomer from this aspect. 

The conventional fabrication process for poly(tetra-fluoro-/)-xylylene) (parylene F) is difficult, involving many process steps, and is more expensive than that for parylene-N. Typically, this process first involves the formation of a dimer, 1,1,2,2,9,9,10,10-octafluoro [2.2]paracyclophane. The dimers are cracked at 720-730 °C to get the monomer TFPX. 

Dolbier Jr WR, Rong XX. Process for the preparation of octafluoro-(2,2) paracyclophane. US patent 5 849962, assigned to Specialty Coating Systems, Inc., DE 1998. 

Figure 12.2 4,5-Dehydro-octafluoro[2.2]paracyclophane (162) and 4,5,15,16-bis(dehydro)octafluoro[2.2]paracyclophane (163).

The fluorine-fluorine scalar coupling interactions have been found to be especially informative in structural investigations of a selection of various mono- and di-substituted octafluoro[2.2]paracyclophanes carried out by Roche and Marchione. In addition to Jpp and Jpp couphngs, these compounds also provided quite large, of about 2 Hz, couphngs across seven, and in some cases even eight bonds. 

Tetrafluoro-p-xylylene 23 has been matrix isolated by flash vacuum pyrolysis of the corresponding octafluoro[2.2]paracyclophane followed by condensation at 30 K with a large excess of argon. This is a further example of the use of matrix isolation to stabilize a highly reactive species produced in a thermal reaction, which then becomes the starting material for photochemical studies. Irradiation of 23 at 248 nm resulted in partial conversion to a new species, which was identified as the tetrafluoroheptafulvene 24 by comparison of the experimental and computed IR transitions. Several possible reaction mechanisms for this rearrangement were proposed, but no intermediate species was detected in the matrix photolysis experiments, so a final conclusion as to the mechanism could not be drawn. 

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