Maurilio Tramontini

Mannich bases in polymer chemistry

Mannich bases, the characteristic structure of which is X sbnd;CH2N< (X = ketoalkyl, phenol, amide, phosphonic group, etc.), are widely employed as polymers or monomeric precursors of polymers in the production of substances with a large number of different applications in industry. This review covers the existing literature on Mannich bases involved in polymer chemistry on the basis of a classification of the polymeric structures which have been synthesized and describes their applications.

Stereochemistry of mannich bases—II : Stereospecific synthesis and absolute configuration of diastereoisomeric 1-phenyl-1,2-dimethyl-3-dimethylamino-propan-1-ols

Abstract During the stereospecific synthesis of diastereoisomeric (+)-1-phenyl-1,2-dimethyl-3-dimethyl-amino-propan-1-ols (III and IV), obtained by reaction of suitable Grignard reagents on α-methyl-β-dimethylamino-propiophenone (I) or on 3-methyl-4-dimethylamino-butan-2-one (II) respectively, the absolute configuration of (−)-amino-alcohol (III) was shown to be 1 R , 2 S . It was also established that (−)-amino-alcohol (IV) has the 1 S , 2 S configuration.

1,3-asymmetric induction—VI : Stereochemistry of the reactions between organo-metals and β-asymmetric amino-ketones☆☆☆

Abstract The stereochemical course of the reaction between organo-metals and β-asymmetric amino-ketones has been investigated by varying the nature of the reagent and the substituents in the substrate, as well as the distance of the amino-group from the reaction center. The relative configurations of the diastereomeric amino-alcohols obtained were assigned, thus determining the direction of the predominant attack by the nucleophile. The stereoselectivity was found to be strongly dependent on the factors investigated, particularly on the nature of the amino-group and of the reagent. No single model of asymmetric induction proved to be suitable for the prediction of the stereochemical results in the above reactions.

Immobilization and stabilization of pectinlyase on synthetic polymers for application in the beverage industry

Fruit juice depectinization can be achieved by means of immobilized pectinlyase (PL, EC 4.2.2.3). PL immobilization on three synthetic polymers, i.e. Eupergit C, Nylon 6 activated with glutaraldehyde and XAD7 activated with trichlorotriazine was tested. Satisfactory activity results were obtained only with activated Nylon 6 and XAD7 (110 and 335 U/g, respectively). As the operational stability of these matrices was low, stabilization was performed by the structure enzyme rigidification through the subsequent cross-linking with glutaraldehyde.

Optically active polymers containing side-chain photoreactive benzoin methyl ether moieties

Abstract Optically active copolymers of (−)-menthyl acrylate (MtA) with racemic α-methylolbenzoin methyl ether acrylate (MBA) as well as of (−)-menthyl vinyl ether (MtVE) with racemic α-vinyloxymethylbenzoin methyl ether (MBVE) have been prepared by radical and cationic initiation, respectively. The reactivity of comonomers as well as spectroscopic and fractionation data suggest that acrylic and vinyl ether copolymers show a tendency towards substantial random and block distributions of monomeric units, respectively. Optical activity at 589 nm of the copolymers seems to exclude any stereoselectivity and stereoelectivity during the copolymerization in both systems. Chiroptical properties indicate that in both series of copolymers an induced optical activity on benzoin-derivative chromophores occurs, which is due to a dissymmetric arrangement of the macromolecules. Circular dichroism data, connected with the n → π∗ electronic transition of the keto group, suggest that the observed ellipticity in MBA/MtA copolymers is substantially due to isolated MBA units. In the case of MBVE/MtVE copolymers both isolated and sequential MBVE units give a contribution to the ellipticity, thus suggesting that the induced optical activity is transmitted through short blocks of MBVE units.

Stereochemistry of mannich bases—IV: Stereospecific synthesis and configurations of diastereoisomeric 3-amino-propan-1-ols☆

Abstract Reactions between Grignard reagents and a number of α-asymmetric β-amino-ketones were found in all cases to be highly stereospecific. All the phenylketo-bases reacted with methylmagnesium derivatives yielding only one of the two possible diastereoisomeric 1-phenyl-1-methyl-3-amino-propan-1-ols, while the corresponding methylketo-bases reacted with phenylmagnesium halides yielding in very high prevalence the other diastereoisomer. The diastereoisomer ratios were determined and the steric configurations were assigned. The results are discussed on the basis of a cyclic model.

Immobilization of catalase on macromolecular supports activated with acid dyes

Abstract Catalase was immobilized on a range of natural and synthetic macromolecular supports (chitosan, wool, silk, amberlite, nylon 6, polyvinylpyrrolidone) undyed or activated by dyeing with sulphonic and carboxylic anionic dyes (Cibacron Blue F3G-A and Erythrosin). The immobilization yield (IY) and the activation yield (AY) were considerably influenced by immobilization conditions (pH, presence or absence of dye and type of dye). The most promising system was the nylon 6 activated by dyeing with Cibacron Blue. The binding ability of this activated support was about 45 000 units/g, one-third of these being active. The technique is simple and suitable for applications employing ordinary and low priced supports, G.R.A.S. and can be easily used in industrial processes. Besides the unchanged optimal pH, the immobilized enzyme gives high half time values in the conditions usually employed in food technology (pH 3–4, room temperature). These are decidedly higher as compared to those of the free enzyme. The interest in this biocatalytic system is partly limited by relevant inactivation due to temperature increase.

Stereochemistry of amino-carbonyl compounds—VII: Absolute and ralative configuration of some diastereomeric 1,3-amino-alcohols.

Abstract The absolute configuration of (+)-4-dimethylamino-2,4-diphenyl-butan-2-ol and (+)-4-piperidino-2-phenyl-pentan-2-ol, the predominant diastereomers obtained by reaction of (+)-3-dimethylamino-1,3-diphenyl-propan-1-one with MeLi and (+)-3-piperidino-1-phenyl-butan-1-one with MeMgI, respectively, was determined by chemical correlation. The relative configurations of the diastereomers afforded by such reactions were thus assigned.

Stereochemistry of mannich bases—I : Absolute configuration of some α-methyl-β-amino-ketones.

Abstract The absolute configuration of (+)-α-methyl-β-dimethylaminopropiophenone (Ia) was found to be S by chemical correlation with R (−)-α-methyl-β-alanine. The absolute configuration of (+)-α-methyl-β-piperidino- and of (−)-α-methyl-β-morpholinopropiophenone (Ib and Ic) was found to be S and R , respectively, by comparison of their ORD spectra with that of the keto-base (Ia).Abstract The absolute configuration of (+)-α-methyl-β-dimethylaminopropiophenone (Ia) was found to be S by chemical correlation with R(−)-α-methyl-β-alanine. The absolute configuration of (+)-α-methyl-β-piperidino- and of (−)-α-methyl-β-morpholinopropiophenone (Ib and Ic) was found to be S and R, respectively, by comparison of their ORD spectra with that of the keto-base (Ia).

The Mannich bases in polymer synthesis: 3. Reduction of poly(β-aminoketone)s to poly(γ-aminoalcohol)s and their N-alkylation to poly(γ-hydroxy quaternary ammonium salt)s

Abstract Several poly(β-aminoketone)s, obtained by polyconensation of bis Mannich bases with bis (secondaryamine)s, have been quantitatively reduced to poly(γ-aminoalcohol)s. The stereochemistry of these polymers, as well as that of the reduction products of the parent bis Mannich bases has been investigated. By N -alkylation of the same polymers, poly(γ-hydroxy quaternary ammonium salt)s have been also prepared.