The equilibrium acidity of lactams with rings of various size and of linear N-substituted amides was measured in dimethyl sulfoxide by the spectrophotometric method. The pK values of these NH-acids thus determined varied in the range 22-27. The data are used to characterize the acidobasic equilibrium between the amide groups of the monomer, polymer and their N-anions during the anionic polymerization of lactams. The effect of acidity on the anionic copolymerization of lactams is also discussed.
The equilibrium acidity of substituted N-(phenylcarbamoyl)-6-hexanelactams, N-butyl-N'-phenylurea and N,N'-diethylurea was determined spectrophotometrically in dimethyl sulfoxide. Using the determined pK values, the effect of activator acidity of the N-(phenylcarbamoyl)-lactam type on the anionic polymerization of lactams was estimated, and the possible effect of the individual types of urea on the concentration of lactam anions was predicted.
Benzoylation of metalated N-benzoyllactams, derived from 7-, 9and 13-membered lactams, gives rise to both N-benzoylenol esters (1) and N,2-dibenzoyllactams (3), whereas in the case of derivatives of 5-and 6-membered lactams only products 3 by C-acylation in position 2 were isolated. In the propionylation of N-benzoyl-or N-propionyl-6-hexanelactam, only products of 0-acylation were formed. The aminolysis of 3 gave rise to 2-benzoyllactams (4). For selected compounds of type 1 -4 the activation effect in the anionic polymerization of 6-hexanelactam was found to be comparable with that of N-acyllactams. The equilibrium acidities in DMSO were measured for 3 and 4.
Polymers of styrene of various type can be readily amidomethylated by a reaction with N-(hydroxymethyl)amides. Analogs of N-methyl-2-pyrrolidone, N-methyl-6-hexanelactam, N-methyl-8--octanelactam, and N,N-dimethylacetamide were prepared by the polymeranalogous amidomethylation. The reaction between poly(styrene-('v-divinylbenzene) and N-(hydroxymethyl)-2--pyrrolidone proceeds by an acceleration mechanism. The extent of the reaction depends on the structure of the polymer and N-(hydroxymethylamide), on the concentration of the catalyst (trifluoroacetic acid) and on the way in which the polymer swells before the reaction. Polymers with bound residues of N-methylamide as solid cosolvents are catalysts of the model nucleophilic substitution reaction between sodium phenoxide and I-bromooctane. A distinct polymer effect was recorded with polymer analogs of N-methyl-2-pyrrolidone in this reaction. ~-~-.-~-. ----~-~--~ ~~-------For many years now, polymers with bound functional groups imitating polar aprotic solvents have attracted attention because of their ability to activate anions in nucleophilic substitution reactions and to act as effective catalysts of reactions occurring by the transfer of the reactant through the phase boundary. In this way the catalytic effects of the polymer analogs hexamethylphosphorus triamide 1 , N,N-dimethylacetamide 1.2, dimethyl sulfoxide 3 • 4 , N-methyl-2-pyrrolidone 5 ,6, N,N-dimethylformamide 7 , and dimethyl sulfone 8 have been documented.Recently, we have published a preliminary report of an easy one-step procedure of preparation of the polymer analog of N-methyl-2-pyrrolidone based on crosslinked polystyrene consisting in the amidomethylation of poly( styrene-co-divinylbenzene) with the N-hydroxymethyl derivative of 2-pyrrolidone; the product was found to be an extremely effective cataly~th under the conditions of a two-phase S-L and a three-phase L-S-L catalysis. The new study is concerned with the preparation of polymers based on various types of polystyrene with bound groupings imitating the structure of N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl-6-hexanelactam, and N-methyl-8-octanelactam by the acid catalyzed amidomethylation of polymers with the corresponding N-(hydroxymethyl)amides and reported the
The efficiency of polymer analogues of oligo(oxyethylene)s and sulfoxides in the activation of nucleophilic substitution reactions were compared by testing to the reaction between sodium phenoxide and 1-bromooctane in 1,4-dioxane. With polymer analogues of crown ethers and polymer networks having the pseudo-crown ether structure the polymer effect can be achieved, i.e. a higher activation efficiency of the polymer analogue (in the L-S system) compared with the efficiency of the unimmobilized compound (in the homogeneous system). The results suggest that several molecules of the linear activator or of side active groupings (chains) on the polymer having the podand structure take part in the formation of the activation site (for the complex formation or solvation of the cation).
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