Ketone molar fractions

FIGURE 15. Effective phase ratio as a function of molar fraction of LPFOS in LDS for alkyl benzene and alkyl phenyl ketone homologous series. Data compiled from Reference 46. 

The nucleophilic substitution approach was also used by several research groups for syntheses of polysulfides with broad variation of the chemical structure and of the reaction conditions [343-352]. For instance, a poly(thioether-ketone) was prepared from DFBP and dry Na2S with variation of the reaction medium [337]. N-Cyclohexylpyrrolidone was found to yield the highest molecular weights. In another publication random copoly(ketone sulfone sulfide)s were prepared by copolycondensation of 4,4 -dichloro-benzophenone and 4,4 -dichlorodiphenylsulfone with NaSH (222) [344]. The crystallinity was found to depend on the molar fraction of benzophenone moieties. 

Fig. 6. Regioselectivity in the ketone fraction expressed as standarized molar ratios of C2/C3 and C2/(C4+C5). Corrections are made so as to have an equal number of C2 and (C4 + C5) positions in the n-alkane chain, irrespective of its chain length. Conditions are the same as in Fig. 4.

Since both molar volume and refractive index are influenced by the actual molecular species present in a solution, molar refraction has some potential value for studying association equilibria. Giles and co-workers (65-68) correlated the method with dielectric constant measurements, and have been the most active users of refractive index for studying compound formation. Reference 68 reviews earlier work (which is sketchy) and lists about forty systems (mostly oxygen containing compounds) that were studied. References 65-67 deal with amide, amine, and azo compounds, plus esters and additional work on alcohols, aldehydes, ketones, and carbohydrates. The method is simple the refractive index of a series of mixtures of varying composition but constant concentration in a solvent is measured. Compound formation is shown by a change in the slope of the n vs. mole fraction plot, such as in Fig. 2-15. 

The phase diagrams expressed in temperature versus volume fraction V2 are shown in Fig. 7.8 for a series of different molar masses of polystyrene dissolved in diisobutyl ketone (the lower curves correspond to lower molar masses). Lower molar masses dissolve at lower temperature and yield a narrower two-phase area. To find the upper critical temperature of phase separation, the UCST, one can insert for low polymer concentrations V2 the first few terms of the series-expansion for In Vj = hi (1 - Vj) given in Fig. 7.8 into the expression for 8AG ,i/dni (given in Fig. 7.7). With the first two terms of the expansion this leads to the equation listed for In a, the activity of the component 1 (8AG ix/dn, = Ani, see also Fig. 7.3). 

Further interesting findings resulted from syntheses of aromatic poly(ether sulfone)s [64, 65]. The fraction of cycles increased at the expense of linear chains with increasing conversions. Due to the lower reactivity, 4,4 -dichlorodiphenyl sulfone yielded lower molar masses than 4,4 -difluorodiphenyl sulfone, with the consequence that the fraction of cycles was lower. Poly(ether sulfone)s derived from tert-butyl catechol ((d) in Formula 7.3) proved to be particularly well suited to MALDI-TOF mass spectrometry. The poly ether with the highest molar mass gave a spectmm showing mass peaks of cycles up to 20 kDa. After fractionation mass peaks of cyclic polyethers up to 27 kDa were achieved and no signals of linear chains were detectable. However, the fraction above 27 kDa certainly contained linear chains, because in a real experiment 100 % conversion without any side reaction cannot be achieved. The formation of cyclic polyethers in syntheses of poly(benzonitrile ether)s (e.g. (a) in Formula 7.4), of poly(pyridine ether)s ((b) in Formula 7.4) and of poly(ether ketone)s was also screened by MALDI-TOF mass spectrometry [66-68]. 

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