Alfrey-Price

Alfrey-Price Q-e schei Alfven waves Algae... 

Acrylamide copolymerizes with many vinyl comonomers readily. The copolymerization parameters ia the Alfrey-Price scheme are Q = 0.23 and e = 0.54 (74). The effect of temperature on reactivity ratios is small (75). Solvents can produce apparent reactivity ratio differences ia copolymerizations of acrylamide with polar monomers (76). Copolymers obtained from acrylamide and weak acids such as acryUc acid have compositions that are sensitive to polymerization pH. Reactivity ratios for acrylamide and many comonomers can be found ia reference 77. Reactivity ratios of acrylamide with commercially important cationic monomers are given ia Table 3. 

Copolymers of VF and a wide variety of other monomers have been prepared (6,41—48). The high energy of the propagating vinyl fluoride radical strongly influences the course of these polymerizations. VF incorporates well with other monomers that do not produce stable free radicals, such as ethylene and vinyl acetate, but is sparingly incorporated with more stable radicals such as acrylonitrile [107-13-1] and vinyl chloride. An Alfrey-Price value of 0.010 0.005 and an e value of 0.8 0.2 have been determined (49). The low value of is consistent with titde resonance stability and the e value is suggestive of an electron-rich monomer. 

Waters61 have measured relative rates of p-toluenesulfonyl radical addition to substituted styrenes, deducing from the value of p + = — 0.50 in the Hammett plot that the sulfonyl radical has an electrophilic character (equation 21). Further indications that sulfonyl radicals are strongly electrophilic have been obtained by Takahara and coworkers62, who measured relative reactivities for the addition reactions of benzenesulfonyl radicals to various vinyl monomers and plotted rate constants versus Hammett s Alfrey-Price s e values these relative rates are spread over a wide range, for example, acrylonitrile (0.006), methyl methacrylate (0.08), styrene (1.00) and a-methylstyrene (3.21). The relative rates for the addition reaction of p-methylstyrene to styrene towards methane- and p-substituted benzenesulfonyl radicals are almost the same in accord with their type structure discussed earlier in this chapter. 

Acrylamide (AM), 1.288-301, 410 Alfrey-Price parameters, 7 617t economic aspects, 1 295-296 health and safety factors, 1 297-300 manufacture, 1 293-295 monomer, 20 460-461 monomer for amino acid resins,... 

Acrylic tow, 11 212 Acrylic weak base resins, 14 389 Acrylonitrile (AN), 1 397—414 10 665-666 11 5 17 228 24 272 acetylene-derived, 1 229 Alfrey-Price parameters, 7 617t azeotropes, l 399t... 

Alfrey-Price parameters, 7 617t reactivity ratio from Alfrey-Price scheme compared with experimental data, 7 618t... 

Hexene, 17 722 20 414 Alfrey-Price parameters, 7 617t catalytic aerogels for epoxidation, l 763t... 

Isophthaloyl chlorides, 19 715 Isophytol, 24 502, 550 Isopolytungstate compounds structures of, 25 383-384 Iso prefix, 13 594-595 Isoprene, 24 501 Alfrey-Price parameters, 7 617t block copolymer synthesis, 7 647t butyl rubber polymers, 4 433 commercial block copolymers, 7 648t glass transition and melting... 

Methyl methacrylate (MMA), 16 227 Alfrey-Price parameters, 7 617t azeotropic mixtures with, 16 236t block copolymer synthesis, 7 647t C-2 routes to, 16 252-254 C-3 routes to, 16 246—252 C-4 routes to, 16 254—257 carbon monoxide in production of, 5 6 chain-transfer constants for, 16 284t comonomer with acrylonitrile, 1 451t cumene as feedstock, 8 156 in flame-retardant resin formulation,... 

Alfrey-Price parameters, 7 617t alkoxycarbonylation of, 16 252 alkylation of, 2 176, 182, 188 20 782 ammoxidation to acrylonitrile,... 

The Q-e scheme neglects steric factors, but it is a useful guide when data for r and Y2 are not available. Following is an approach that relates the reactivity ratios to the Alfrey-Price e values ... 

When the reactivity ratios ry can be expressed in terms of the parameters of the well-known Q-e scheme of Alfrey-Price [20,157], the condition (4.20) always holds [147, 150] and in the case of terpolymerization the general Eqs. (3.8) and (4.10) transform into the simplified equation [158]. It is rather curious that similar equations have been derived at the end of the 1940s [159] within the framework of the Alfrey-Price scheme, being investigated even for the general case of copolymerization of arbitrary number m of monomer types. 

The violation of the condition (4.20) for the particular system means that the latter can not be described by the Q-e scheme. However, in addition to this scheme, there are known some others, also applied for the description of the reactivity of the polymer radical in propagation reactions [160], One such scheme proposed by Bamford [161, 162] was successfully used by Jenkins [163] for an interpretation of the experimental values [150] of parameter H for a number of ternary systems. For many of these the values of H are noticeably different from unity, as it has to be according to the predictions of the Alfrey-Price scheme, but are in satisfactory agreement with the values calculated through the Bamford scheme [163, 160],... 

All the mentioned types of the nontrivial dynamic behavior are excluded for the systems where the reactivity ratios ry can be described by the expressions of the well-known Alfrey-Price Q-e scheme [20], and as a result they are to follow the simplified terminal model (see Sect. 4.6). In these systems, due to the relations Bj(X)/Bj(x) = ajj/ajj which holds for all i and j, the functions 7e,-(2) according to relations (4.10) are the ratios of the homogeneous polynomials of degree 2. Besides, for the calculations of the coefficients ak of Eq. (5.11) one can use the simple formulae presented in terms of determinants Dj and D [6, p. 265]. The theoretical analysis [202] leads to the conclusion that in such systems even the limited cycles are not possible and all azeotropes are certainly unstable. Hence any trajectory H(p) and X(p) when p -> 1 inevitably approaches the SP corresponding to the homopolymer the number of which can be from 1 to m. The set of systems obtained due to the classification within the framework of the simplified model essentially impoverishes in comparison with the general case of the terminal copolymerization model since some types of systems cannot be principally realized under the restrictions which the Q-e scheme puts on the reactivity ratios r. ... 

The application of NMR spectroscopy data to estimate the reactivity ratios is regarded to be very promising [272]. The Q and e values of the Alfrey-Price scheme may be immediately calculated analyzing the shifts of the corresponding bands in carbon-NMR spectra Such data obtained for more than fifty pairs of monomers are tabulated in Ref. [273]. A quite different method based on the application of the trivial expressions ... 

Alfrey—Price e value bond electronegativity electronegativity of element A electronegativity of element B... 

The electron richness of vinylferrocene as a monomer has been demonstrated in its copolymerization with maleic anhydride, in which 1 1 copolymers were obtained over a wide range of feed ratios and ri r2 = 0.003 [13]. Subsequent copolymerization of vinylferrocene with classic organic monomers, such as styrene [13], Ai-vinyl-2-pyrrolidone [15], methyl methacrylate [13] and acrylonitrile [13] were carried out and the Alfrey-Price Q and e parameters [16] determined. The value of e is a semiempirical measure of the electron richness of the vinyl group. The best value of e for vinylferrocene is about —2.1, which, when compared with the e values of maleic anhydride (-H 2.25), p-nitrostyrene (-1-0.39), styrene (—0.80), p-Ai,Ai -dimethyl-aminostyrene ( — 1.37) and l,T-dianisylethylene ( — 1.96), again emphasizes the electron rich nature of the vinyl group in vinylferrocene. 

Until the appearance of the Alfrey-Price Q — e scheme, it has been necessary to refer relative monomer reactivity ratios to the particular two-... 

In radical copolymerization the Alfrey-Price Q-e scheme has been proposed for systematizing a large amount of data and for correlating the reactivity of a monomer to its chemical structure. In this scheme the monomer reactivity ratios are given by the following equations ... 

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