Acylated polymers

The Manufacture of Acylic Polymers, CM-107, Rohm and Haas Co., Philadelphia, Pa. 

In a similar fashion, the cationic polymerization of 2-oxazolines has been extensively studied and was found to provide the first verified entry to linear-poly(alkyleneimine) architectures. These acylated polymers were first recognized as precursors to linear poly(ethyleneimines) in the early 1960s [25]. Hydrolysis experiments demonstrated that deacylation of these products to linear PEI was possible. The original polymerization mechanism proposed by Tomalia et al. 

Cuno Cellulose/acylic polymer composite Protein A/G, benzami-dine... 

The greatest ratio of the relative, apparent rate constant pvim/ im( = 390) is observed for the reaction system where the hydroidiobic interaction is expected to be the greatest (long acyl-chain substrate in low alcohol medium). The transformation of the kinetic behavior from the pseudo-first order to tte Midiaelis-Menten type also paralleled the increasing hydroj obic interaction. The acceleration behavior mentioned above is concurrent mth this transformation and explicable by the increa d hydro diobic interaction between long-chain substrates and the partially acylated polymer (see also Table 4—3). 

The accumulation of the acyl intermediate (PVIm-Ac ) was established unequivocally by studying the acylation and deacylation behaviors of the polymer separately. Overberger and Glowaky (60) allowed polyvinylimidazole 1 to react with loi -chain acyl substrates SJJ" 15 and separated the partially acylated polymer by utilizing gel permeation chromatography (Sephadex LH-20). Table 4—3 gives first-order rate coie stants for acylation (kobs) and deacylation (ka) reactions, is larger than kobs fot... 

The final difference in the copolymerization of carbon monoxide with propene or styrene is the overall connectivity of the initial polymer generated under some conditions. The polymer generated from the copolymerization of carbon monoxide and propene in protic solvents consists of the fused tetrahydrofuran ketal structure shown in Figure 17.17. This polymer reopens to the polymer shown in Figure 17.13 upon addition of acid in alcohol. Several mechanisms for formation of this product have been proposed, and the origin of the ketal structure remains unresolved. Polymers formed in aprotic solvents form the acylic polymer. 

By acylation of polymers 2 and 2 the benzoate ester polymers and the benzamide polymers were synthesized. Charging studies of these systems revealed relationships betwa both aliphatic and aromatic molecular structures and charging.The charging of the acylated polymers was found to be less positive (more negative) than the parent polymers. Silylation causes similar changes in hydroxy or amino functionalized materials, as does acylation of alcohols such as poly(vinyl alcohol) and ethyl cellulose. ... 

Non-ionic (hydrophobic) association of the polymeric catalyst-substrate has also been shown to increase the catalytic activity. Thus, the rate of hydrolysis of 3-nitro-4-acyloxybenzoic acid (6) by polyvinylimidazole, increases with increasing bulk of acyloxy group (Over-berger and Sannes, 1974). It was observed that the deacylation step of the intermediate polymeric acylimidazole is rate-determining. Since the acylated polymer becomes more hydrophobic, because of the extra group attached to the polymer, apolar associations increase with the chain length of the acyl group, and, hence increase the catalytic activity. 

Dry the acylated polymer in vacuo before the next step of the reaction sequence. Dissolve the acylated polymer in 5 mL dry methanol. To this solution add 3 eq sodium methoxide, and stir the reaction mixture at room temperature under nitrogen atmosphere. 

Then N-Boc-O-benzylserine is coupled to the free amino group with DCC. This concludes one cycle (N° -deprotection, neutralization, coupling) in solid-phase synthesis. All three steps can be driven to very high total yields (< 99.5%) since excesses of Boc-amino acids and DCC (about fourfold) in CHjClj can be used and since side-reactions which lead to soluble products do not lower the yield of condensation product. One side-reaction in DCC-promoted condensations leads to N-acylated ureas. These products will remain in solution and not reaa with the polymer-bound amine. At the end of the reaction time, the polymer is filtered off and washed. The times consumed for 99% completion of condensation vary from 5 min for small amino acids to several hours for a bulky amino acid, e.g. Boc-Ile, with other bulky amino acids on a resin. A new cycle can begin without any workup problems (R.B. Merrifield, 1969 B.W. Erickson, 1976 M. Bodanszky, 1976). 

Sulfonated styrene—divinylbensene cross-linked polymers have been appHed in many of the previously mentioned reactions and also in the acylation of thiophene with acetic anhydride and acetyl chloride (209). Resins of this type (Dowex 50, Amherljte IR-112, and Permutit Q) are particularly effective catalysts in the alkylation of phenols with olefins (such as propylene, isobutylene, diisobutylene), alkyl haUdes, and alcohols (210) (see Ion exchange). Superacids. 

MPD-1 fibers may be obtained by the polymeriza tion of isophthaloyl chloride and y -phenylenediamine in dimethyl acetamide with 5% lithium chloride. The reactants must be very carefully dried since the presence of water would upset the stoichiometry and lead to low molecular weight products. Temperatures in the range of 0 to —40° C are desirable to avoid such side reactions as transamidation by the amide solvent and acylation of y -phenylenediamine by the amide solvent. Both reactions would lead to an imbalance in the stoichiometry and result in forming low molecular weight polymer. Fibers are dry spun direcdy from solution. 

The presence of the L-form of mannose is unusual. The side-chain substitution is randomly distributed (242) approximately two-thirds of the side chains ate rhamnose. The repeat unit may also contain an 0-acyl group, but the distribution of these units has not been completely determined. The polymer is moderately soluble in water but is insoluble in isopropanol solutions, which are used to obtain the polymer from the culture medium. A method for producing a rapidly hydrating form of welan is avaUable (243). 

Liquid crystal polyesters are made by a different route. Because they are phenoHc esters, they cannot be made by direct ester exchange between a diphenol and a lower dialkyl ester due to unfavorable reactivities. The usual method is the so-called reverse ester exchange or acidolysis reaction (96) where the phenoHc hydroxyl groups are acylated with a lower aHphatic acid anhydride, eg, acetic or propionic anhydride, and the acetate or propionate ester is heated with an aromatic dicarboxyHc acid, sometimes in the presence of a catalyst. The phenoHc polyester forms readily as the volatile lower acid distills from the reaction mixture. Many Hquid crystal polymers are derived formally from hydroxyacids (97,98) and thein acetates readily undergo self-condensation in the melt, stoichiometric balance being automatically obtained. 

PoIysuIfonyIa.tlon, The polysulfonylation route to aromatic sulfone polymers was developed independendy by Minnesota Mining and Manufacturing (3M) and by Imperial Chemical Industries (ICI) at about the same time (81). In the polymerisation step, sulfone links are formed by reaction of an aromatic sulfonyl chloride with a second aromatic ring. The reaction is similar to the Friedel-Crafts acylation reaction. The key to development of sulfonylation as a polymerisation process was the discovery that, unlike the acylation reaction which requires equimolar amounts of aluminum chloride or other strong Lewis acids, sulfonylation can be accompHshed with only catalytic amounts of certain haUdes, eg, FeCl, SbCl, and InCl. The reaction is a typical electrophilic substitution by an arylsulfonium cation (eq. 13). 

Reactions with Acids. Oigaiiic acids form acylates when heated with tetraalkyl titanates. Best results ate obtained using only one or two moles of acid, as attempts to force the reaction with three or four moles of acid can yield polymers. 

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

A -Piperideine — see Pyridine, 2,3,4,5-tetrahydro-A -Piperideine — see Pyridine, 1,2,3,4-tetrahydro-A -Piperideine — see I ridine, 1,2,3,6-tetrahydro-Piperideines — see Pyridines, tetrahydro-Piperidine, 1-acryIoyI-polymers, 1, 284 Piperidine, JV-acyl-... 

Schiff s bases also underwent C or N acylation with isocyanates (698) and isothiocyanates (698,701). Further studies provided 2 1 and 2 2 reaction products of arylisothiocyanates and enamines (702) and polymers derived from enamines and bisisocyanates (703). 

A strain of Acinetobacter calcoaceticus produces an unusual polysaccharide called emulsan. It is a complex polymer comprising about 15% fatty acyl esters and 20% protein. This structure enables it to act as an emulsifying agent, stabilising hydrocarbon/water emulsions at very low concentrations (0.1-1.0%). This property,... 

As revealed by IR-spectroscopy, the attachment of the polymer proceeds via acylation of aminopropyls absorbances of both amides (1650 cm-1) and esters (1740 cm-1) contribute to the spectrum of polyacrylate-coated aminopropyl-Aerosil (specific surface area 175 m2/g) [55], During the reaction, the accumulation of p-nitrophenyl ester groups in the support is accompanied by the liberation of p-nitrophenol into the contacting solution. Thus, the evaluation of the conformational state of adsorbing macromolecules can be performed by the simultaneous study of both processes by UV-spectroscopy as shown in Fig. 7. Apparently, at... 

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