Crystalline derivatives preparation hydrocarbons

Because of the chemical inertness of the paraffin hydrocarbons and of the closely related cycZoparaffins, no satisfactory crystalline derivatives can be prepared. Reliance is therefore placed upon the physical properties (boding point, density, and refractive index) of the redistilled samples. These are collected together in Table III,6. 

In spite of the fact that a double or triple bond is very reactive, there is no general method known for the preparation of solid derivatives. A series of unsaturated hydrocarbons (especially terpenes) can be identified by conversion them to nitroso chlorides (16). Crystalline derivatives are often obtained by addition of HCl or HBr ... 

The introduction of perfluorinated groups generally favors microphase separation due to the immiscibility of fluorocarbons with hydrocarbons [66]. Norbornene derivatives with perfluorinated endgroups in the side chain were prepared by Wewerka et al. [67]. Monomer XII contained a relatively long (CF2)8-chain, separated via a long spacer (11 methylene-groups) from the norbornene, whereas monomer XIII has two relatively short (CH2)2(CF2)4-side chains (Fig. 11). Homopolymers and block copolymers were synthesized with one fluorinated monomer (XII or XIII) and one non-fluorinated non-liquid crystalline monomer (NBDE or COEN) with the Schrock-type initiators 4 and 5, respectively, leading to microphase-separated block copolymers. Table 9 and Table 10 summarize the physico-chemical properties of the homopolymers and block copolymers. 

The same group reported on the synthesis and characterization of all-hydrocarbon MCLCPs, poly-(XXXX), and their hydrogenated derivatives poly-(XXXXI), based on 4,4 -bis(a-co-alkenyl)-l,r-biphenyl derivatives, see Fig. 23. Monomers with different a-co-alkenyl chain lengths were used to prepare not only the corresponding homopolymers but also statistical copolymers. Crystallinity, thermal transition properties and LC properties were studied. 

The dithiocine tetraoxide derived from cyclocondensation of binaphthodithiol with dichloroethylene and oxidation (eq 8) is a chiral version of the bis(phenylsulfonyl)ethylenes. These compounds are useful acetylene equivalents in cycloaddition reactions (see l,2-Bis(phenylsulfonyl)ethylene). Indeed, a chiral acetylene equivalent allows the preparation of optically active hydrocarbons which would be difficult to prepare by classical methods. The dithiocine tetroxide reacts with nonsymmetric dienes to give a single crystalline diastereomeric adduct in most cases. Adducts (1) and (2) were obtained from acyclic and cyclic dienes. 

This product is best obtained by heating dehydroquininc with about five times its weight of arsenic trichloride in an oil-bath at 130" to 135" for three hours, in the absence of a solvent. It may also be prepared by digesting the previous compound with aqueous ammonium carbonate. It darkens at 199° to 200° C., sinters at about 204° C., and melts at 207 to 209° C. it is easily soluble in alcohols and pyridine, very sparingly soluble in chloroform and acetone, and insoluble in ether, ethyl acetate, aromatic hydrocarbons, and carbon disulphide. Its salts arc not crystalline. The fact that it forms a benzoyl derivative shows the presence of a free hydroxyl group, and consequently the attachment of the arsenic to the vinyl group. 

Together with benzene and naphthalene two other hydrocarbons are obtained from coal tar though in much smaller amounts. They are anthracene and phenanthrene, both of which have the formula CuHjo. Anthracene together with phenanthrene is present in the coal tar distillate which boils above 270°. The yield of anthracene is about 0.25 to 0.45 per cent of the tar. The crude distillate is purified by a second distillation and separated into two fractions (i) A product known as 50 per cent anthracene which is crystalline and still contains phenanthrene. (2) A less volatile non-crystalline oil known as anthracene oil. The 50 per cent anthracene is largely used, just as it is without further purification, in the preparation of alizarin, itsmost important derivative. To obtain pure anthracene from the crude 50 per cent product it is first redistilled after addition of potassium carbonate which forms a non-volatile compound with a constituent known as carbazole. 

Similar copolyimide was prepared using 3,7-diamino-2,8(6)-dimethyldibenzothiopheneS,5-dioxide (DDBT) instead of m-SED and its performance for olefin/paraffm separation was investigated [74]. Block copolymers of liquid crystalline polyamide and amorphous PI were prepared from a two-pot polycondensation reaetions [75]. Hydrocarbon (C-2 and C-3) separations in copolyimide dense membranes derived from 6FDA, DDA and 1,5-naphthalene diamine (NDA) was studied [76]. Gas transport properties of 6FDA, DDA and 3, 3 -diaminodiphenyl sulfone (DIDS) was reported [77]. 

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