Ether bonded packings

Recently, a series of ether bonded phases with the composition =Si(CH2)30(CH2-CH2 0)pR (where n ranges from 1 to 3 and R is either CH3, C2H5 or n-C Hg) has been Introduced as packings for hydrophobic interaction chromatography (HIC) of protelns. The silanes were synthesized in a two-step procedure the ether... 

The Tgs (253-284°C) of these polyimides were higher than that of PI-(HQDA-4,4 ODA) (Table 7.12). As aromatic bulky fluorene moieties combined short aromatic jc-conjugation with a cardo structure, the e values of the polyimides were lower without decreasing thermal stability. Asymmetric bulky groups such as fluorene disturb the chain packing and enhance the free volume in the polyimides. However, as internal rotation of the ether bonds is suppressed, the thermal stability of the polyimides does not decrease greatly. 

Permaphase ETH (C-7 ether chemically bonded to pellicular 30-50 mesh glass packing)... 

For instance, the activation energy for butene formation from n-butyl alcohol is 140 lOkJmol-1 on HZSM-5 and only 95 lOkJmol-1 on AAS. At 378 K, 94% ether plus 6% butene are formed over HZSM-5, whereas 43% ether and 57% butene are formed over AAS. Bearing in mind that butyl alcohol molecules, as well as those of intermediates and products of their dehydration, have dimensions closely similar to the diameter of the zeolite channels, we infer that a liquid-like packing of butyl alcohol molecules and other reaction participants occurs in the channels (as schematized in Fig. 5). We opine that some specific ordering of the adsorbed species in the catalyst channels may be induced by hydrogen bonding and hydrophobic interactions between them. 

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