Hydrogenated cyclic

Prefixes are of two kinds, detachable and nondetachable. Nondetach-able prefixes, such as bicyclo, spiro, benzo, aza, ethano, are integral parts of the parent name and should not be separated from it. Their use has been described already. Detachable prefixes almost invariably refer to substituents and appear in alphabetical order before the parent name. Hydro and subtractive prefixes (e.g., demethyl) have sometimes been treated as nondetachable, appearing immediately before any other nondetachable prefixes, but it is preferable to treat them as detachable except when they do not have associated locants. This exception arises in particular when the name of a fully hydrogenated cyclic molecule is derived from a fully unsaturated parent name, e.g., 2-iodoperhydro-1-azanaphthalene (or 2-iododecahydro-l-azanaphthalene), 2-nitrotetra-hydrofuran. 

The reaction is most probably initiated by radical attack of a reduced carbonyl function on the aromatic ring in the adjacent system. The product is formed as the radical anion but reoxidized by air during work-up. In the presence of proton donors, or in alcoholic solvents, reduction of 98 gives a mixture of acyclic and partly hydrogenated cyclic products [288]. Substituted 98, such as the 4,4, 5,5 -tetracarboxylic acid, gives coupling in basic alcoholic medium but not in DMF [289]. 

The catalytic hydrogenation of benzene has been carried out as a model reaction to increase the hydrogenated cyclic compounds from aromatics. Catalyst samples containing nickel on different supports were prepared and tested. It was found that a-Al203 supported nickel showed the best activity for benzene conversion reaction. Nickel metal area, its dispersion and nickel crystal size were determined. The best activity is obtained with 40% nickel concentration (as oxide) and at the optimum nickel crystallite size of 196A° and optimum metal area of 10.8m2/g. 

In this chapter we show how hydrogenated cyclic PDMS is prepared, characterised and investigated. These studies form the basis of our preparation and characterisation of the first deuterated cyclic polymers [12] [13] [14]. These are per-deuterated PDMS [(CD3)2SiO], and they were obtained by a modification of the method described by Beltzimg and coworkers [15]. Preparative GPC was used to prepare sharp fractions in a similar way to the hydrogenated materials. 

Figure 6 GLC trace of a hydrogenated cyclic PDMS fraction containing rings with 10 to 42 skeletal bonds.

Table I Peak assignments for the EIMS spectrum of a hydrogenated cyclic PDMS fraction. ...

Investigations of Hydrogenated Cyclic and Linear Poly(dimethylsiloxanes). 

The H spectrum of the deuterated product shows the almost total deuteration due to the absence of peaks at s proximately 0 ppm. All of the phenyl groups have been completely removed from the silane and the hydrolysis has produced deuterated PDMS of high purity. The minute peaks observed at 7.27 and 7.37 ppm are due to residual solvents (CHCI3 and CgH respectively). The large peak at 5.31 ppm is due to the dichloromethane used as a reference for calculating the percentage deuteration in comparison with a similar spectrum recorded with the hydrogenated cyclic tetramer (D4). 

Narrow fractions of hydrogenate cyclic poly(dimethylsiloxanes) have b n prepare in good yield. A comprehensive series of analytical techniques have displaye the purity of the products and demonstrated the isolation of cyclic polymers. 

---