Sulfonates, carbonylation

The second synthetic route to PAE containing quinoxaline units involved the reaction of an aromatic dihydroxy quinoxaline or aromatic bis(hydroxy-quinoxaline) with activated aromatic difluoro compounds (Eq. (3)) [15]. The dihydroxy quinoxaline and bis(hydroxyquinoxaline) monomers were readily prepared from the condensation of 1,2-diaminobenzene with 4,4 -dihydroxyben-zil and aromatic bis(o-diamines) with 4-hydroxybenzil, respectively. The Tgs of a series of PAE containing quinoxaline units are presented in Tables 3 and 4. For these polymers, the trend for the Tg is sulfone > carbonyl > terephthaloyl-> isophthaloyl. This trend holds for most polymer families when polymers of similar molecular weights are compared. Several polyphenylquinoxalines of the same chemical structure as those in Table 3 were also prepared by the poly-... 

The Tgs of poly(arylene ether phenylimidazole)s containing pendent groups are given in Table 7 [25]. Within each of the 4 series of polymers, the Tg trend is the same as previously pointed out, namely sulfone > carbonyl > terephthaloyl > isophthaloyl. In addition, within the last three series of polymers in Table 7, the Tg trend is CF3 > CH3 > C2H5. The series with the highest Tgs was the first one in Table 7 where both R and R substituents on the pendent phenyl ring were CF3 groups. 

The Tgs and in some cases, the Tms of several poly(arylene ether-1,3,4-oxadiazolejs are reported in Table 12. The last five polymers in Table 12 display the same Tg trend as seen for other polymers, namely phenylphosphine oxide > sulfone > carbonyl > terephthaloyl > isophthaloyl. The terephthaloyl polymer could be heated above the Tm, and subsequently quenched to the amorphous form, and then annealed at 330 °C to induce crystallinity. Once the Tms of the carbonyl and isophthaloyl polymers were exceeded, crystallinity could not be reintroduced by annealing at 300 to 330 °C for several hours. The Tg and Tm of the isophthaloyl polymer are abnormally close. 

Peroxynitrite, like other oxidants, reacts with proteins, first oxidizing cysteine methionine and tryptophan residues (A7). The reaction products are sulfones, carbonyl moieties, and dityrosines (K23, M29). Formation of protein hydroperoxides and protein fragmentation was also observed (B7, G6). Nitric oxide induces oxidation of methionine residues, thus effecting oxidative damage to proteins (Cl 1). It also reacts with Fe-S clusters of aconitase (D15), though in most cases it is difficult to assess whether these effects are produced by the NO itself, or rather by a more reactive secondary product such as peroxynitrite (C5). At physiological... 

Halo sulfone Carbonyl compound Yield of epoxy sulfone (24) (%)... 

As shown in Figure 4.11, the methanol spectroscopic scale is very weakly correlated to the methanol basicity ( = 42, r = 0.737). Only 54% of the variance of AG is explained by Av. Some resolution of the scatter diagram is, however, achieved by noting good correlations of AG with Av(OH) when separating the families ofpyridines, ethers and polar bases (nitrile, sulfoxide, sulfone, carbonyls and phosphoryls) which obey Equations 4.29,4.30 and 4.31,... 

Alkyl halides and sulfonates are the most frequently used alkylating acceptor synthons. The carbonyl group is used as the classical a -synthon. O-Silylated hemithioacetals (T.H. Chan, 1976) and fomic acid orthoesters are examples for less common a -synthons. In most synthetic reactions carbon atoms with a partial positive charge (= positively polarized carbon) are involved. More reactive, "free carbocations as occurring in Friedel-Crafts type alkylations and acylations are of comparably limited synthetic value, because they tend to react non-selectively. 

The Julia-Lythgoc olefination operates by addition of alkyl sulfone anions to carbonyl compounds and subsequent reductive deoxysulfonation (P. Kocienski, 1985). In comparison with the Wittig reaction, it has several advantages sulfones are often more readily available than phosphorus ylides, and it was often successful when the Wittig olefination failed. The elimination step yields exclusively or predominantly the more stable trans olefin stereoisomer. 

The reaction of alcohols with acyl chlorides is analogous to their reaction with p toluenesulfonyl chloride described earlier (Section 8 14 and Table 15 2) In those reactions a p toluene sulfonate ester was formed by displacement of chloride from the sulfonyl group by the oxygen of the alcohol Carboxylic esters arise by displacement of chlonde from a carbonyl group by the alcohol oxygen... 

A major difference between alcohols and thiols concerns their oxidation We have seen earlier m this chapter that oxidation of alcohols gives compounds having carbonyl groups Analogous oxidation of thiols to compounds with C=S functions does not occur Only sulfur is oxidized not carbon and compounds containing sulfur m various oxida tion states are possible These include a series of acids classified as sulfemc sulfimc and sulfonic according to the number of oxygens attached to sulfur... 

Numerous diamines and aromatic dianhydrides have been investigated. WhoUy aromatic Pis have been stmctiirally modified by incorporating various functional groups, such as ether, carbonyl, sulfide, sulfone, methylene, isopropjlidene, perfluoroisopropyUdene, bipyridyls, sdoxane, methyl phosphine oxide, or various combinations of these, into the polymer backbone to achieve improved properties. The chemistry and apphcations of Pis have been described in several review articles (4). 

Benzene Nucleus Reactions. Ring substitutions, such as sulfonation and nitration, can be effected without destmction of the carbonyl group. Under the influence of the carbonyl group, meta substitution usually occurs. 

In addition they may contain ether, amide, carbonyl, sulfone, or other functional groups. References 28 and 29 provide excellent reviews of polyimide chemistry. 

Dyestuff organic chemistry is concerned with designing molecules that can selectively absorb visible electromagnetic radiation and have affinity for the specified fiber, and balancing these requirements to achieve optimum performance. To be colored the dyestuff molecule must contain unsaturated chromophore groups, such as a2o, nitro, nitroso, carbonyl, etc. In addition, the molecule can contain auxochromes, groups that supplement the chromophore. Typical auxochromes are amino, substituted amino, hydroxyl, sulfonic, and carboxyl groups. 

Compound (253) is formed from benzaldehyde and methylhydroxylamine-O-sulfonic acid in 35% yield. With ethyl-substituted chloramine or hydroxylamine-O-sulfonic acid yields do not exceed 10%, which is assumed to be due to steric hindrance and is foreseeable for both carbonyl addition and O —N bond formation. 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

The role of IR spectroscopy in the early penicillin structure studies has been described (B-49MI51103) and the results of more recent work have been summarized (B-72MI51101). The most noteworthy aspect of a penicillin IR spectrum is the stretching frequency of the /3-lactam carbonyl, which comes at approximately 1780 cm" This is in contrast to a linear tertiary amide which absorbs at approximately 1650 cm and a /3-lactam which is not fused to another ring (e.g. benzyldethiopenicillin), which absorbs at approximately 1740 cm (the exact absorption frequency will, of course, depend upon the specific compound and technique of spectrum determination). The /3-lactam carbonyl absorptions of penicillin sulfoxides and sulfones occur at approximately 1805 and 1810 cm respectively. The high absorption frequency of the penicillin /3-lactam carbonyl is interpreted in terms of the increased double bond character of that bond as a consequence of decreased amide resonance, as discussed in the X-ray crystallographic section. Other aspects of the penicillin IR spectrum, e.g. the side chain amide absorptions at approximately 1680 and 1510 cm and the carboxylate absorption at approximately 1610 cm are as expected. 

Polymerization of olefins such as styrene is promoted by acid or base or sodium catalysts, and polyethylene is made with homogeneous peroxides. Condensation polymerization is catalyzed by acid-type catalysts such as metal oxides and sulfonic acids. Addition polymerization is used mainly for olefins, diolefins, and some carbonyl compounds. For these processes, initiators are coordination compounds such as Ziegler-type catalysts, of which halides of transition metals Ti, V, Mo, and W are important examples. 

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