- Email: [email protected]
Polymer-bound thiamine models: Polymer effects on the catalytic activity of polystyrene-bound thiazolium salts in the Benzoin condensation reaction
125 This and similar reactions can be used to attach the required reagents to the polyphosphate or polyphosphonate chains. Reactions are highly specific. Publication details unknown.
Enantio- and Substrate-selective Macroporous Polymers by Molecular Imprinting BiSrje S e l l e r g r e n , M a t t i Lepist~5 a n d K l a u s M o s b a c h , University of Lund, Lund, Sweden Enantio- and substrate-selective macroporous polymers were prepared by a non-covalent imprinting procedure (pre-arrangement). Methacrylic-based polymers were hereby obtained which were selective for amino acid derivatives. In chromatography these allowed a base-line separation of the enantiomers of phenylalanine anilide, and they possessed an enhanced selectivity for its corresponding substrate by comparison with substrate analogues. Publication details unknown.
Application of the Degree of Swelling to the Analytical Characterization of Styrene Copolymers and their Chloromethyl and Phosphinomethyl Derivatives E. P a e t z o l d , H . P r a c e j u s a n d G . O e h m e , Academy of Science of G.D.R., Rostock, G.D.R. Crosslinked polymeric materials have been used frequently as supports for heterogenizing of transition metals. Usually, the properties of the supports influence activity and selectivity of catalysts. We prepared four different polystyrene resins crosslinked with 2% divinylbenzene and functionalized these matrices in the following sequence, obtaining ten differently substituted derivatives 2 and 3: (
~
CH3OCH2CI,(~-CH2CI
1
2
LiPPh2>(~!-CH2PPh
2
3
To obtain information about the properties (e.g. penetration) of the resins we investigated the degree of swelling q in toluene as standard solvent. The degree of swelling of the matrix polymer 1 was found to be dependent on the polymerization process and is changeable by the functionalization from 1 to 2 and from 2 to 3, respectively. The ratio qx/qo (degree of swelling of derivative/degree of swelling of matrix resin) shows a linear correlation with the degree of substitution. Significant deviations could be observed in the case of intraresin reactions, e.g. between phosphinomethyl groups and chloromethyl groups in 3. Some proposals are given for a rational analytic use of the degree of swelling in the characterization of organic supports. To be submitted to
ReactivePolymers.
Polymer-bound Thiamine Models: Polymer Effects on the Catalytic Activity of Polystyrene-bound Thiazolium Salts in the Benzoin Condensation Reaction H . J . v a n d e n B e r g , G . C h a l l a , State University of Groningen, Groningen, The Netherlands, a n d U . K . P a n d i t , University of Amsterdam, Amsterdam, The Netherlands The catalytic activities of polystyrene-bound thiazolium salts ( l a - b ) and their low molar mass analogues have been determined in the condensation reaction of benzaldehyde to benzoin, under standardized reaction conditions. The activity of the soluble polymer (la) was about two times lower than that of its low molar mass counterpart, while the activities of macroporous polymers were three to four times lower than that of the low molar mass model (depending on the degree of functionalisation of the macroporous polymers). The polymer effect was investigated in terms of diffusional effects, local concentration effects and microenvironmental effects. It is shown that the decreased activity
126 of immobilized thiazolium salts is predominantly a result of steric hindrance of the polymer matrix. The insoluble immobilized thiazolium salts could be used repeatedly without loss of catalytic activity, provided that equimolar amounts of cocatalyst (triethylamine) were used. Excess of amine accelerated the benzoin condensation, but decreased the stability of the catalyst.
ta:(~)= Linear Polystyrene Me
Ho~S >
b:(~) = Macroporous Styrene-DVB copolymers
Ct-
Submitted for publication in
Journal of Molecular Catalysis.
An Attempt at Classification of Solid Superacids R o m u a l d B o g o c z e k a n d J o a n n a S u r o w i e c , Technological Institute of Chemical and Food Industry, Wroctaw, Poland The development of liquid superacid chemistry was accompanied by the appearance of a new generation of such acids, i.e., of solid superacids. Their preparation consists in application of polymeric matrices as carriers for systems with increased acidity. So solid superacids can be considered as polymer-supported reagents and catalysts. Measurements of superacidic system acidity with Hammett function H 0 allows to include or not the tested systems in the category of superacids. Most authors suggest using the term superacid only for the systems showing H o < - 12 or H 0 < - 1 5 . At the same time there is a tendency to refer to systems with higher acid strength on solid supports as superacids, without measuring H 0. The systems show, however, catalytic activity in hydrocarbon transformations. Irrespective of the H 0 function, we suggest the following classification of superacidic systems: 1. According to the state of aggregation: liquid and solid. 2. According to the number of components: simple and composite, i.e., multicomponent, usually two- or three-component. 3. According to the acid character of the components: protonic (Br~Snsted), aprotonic (Lewis), and conjugated (BriSnsted and Lewis acid mixtures). Thus, within the group of solid superacids the following systems can be distinguished: Brrnsted, Lewis, and BrSnsted-Lewis systems on inorganic or organic carriers. Moreover, some authors refer to acid systems on the basis of fluoric polymers containing sulfonic groups (e.g. Nation-H) as superacids. Research on superacid systems on organic polymeric carriers is proceeding in three directions: 1. The fixation of a Lewis acid (e.g., A1C13, SbCI 3, SbF5, BF3) to a styrene-divinylbenzene matrix. 2. The preparation of polymeric systems of Brrnsted-Lewis type (e.g., Amberlyst 15 + AIC13). 3. The increase of acidity of conventional polyacids of Bronsted type, e.g., of cation exchange resins with sulfonic groups by fluorination. Publication details not decided.
Phenol Halogenation with the Use of Poly(styrene-divinylbenzene)halogeno-Suifonamides R o m u a l d B o g o c z e k a n d E l ~ b i e t a K o c i o / e k - B a l a w e j d e r , Technological Institute of Chemical and Food Industry, Wroclaw, Poland Phenol in 0.1 molar aqueous solution has been brought into contact with the following macroporous poly(styrene-divinyibenzene)SO2NH2 halogen derivatives in bead form:
Enantio- and Substrate-selective Macroporous Polymers by Molecular Imprinting BiSrje S e l l e r g r e n , M a t t i Lepist~5 a n d K l a u s M o s b a c h , University of Lund, Lund, Sweden Enantio- and substrate-selective macroporous polymers were prepared by a non-covalent imprinting procedure (pre-arrangement). Methacrylic-based polymers were hereby obtained which were selective for amino acid derivatives. In chromatography these allowed a base-line separation of the enantiomers of phenylalanine anilide, and they possessed an enhanced selectivity for its corresponding substrate by comparison with substrate analogues. Publication details unknown.
Application of the Degree of Swelling to the Analytical Characterization of Styrene Copolymers and their Chloromethyl and Phosphinomethyl Derivatives E. P a e t z o l d , H . P r a c e j u s a n d G . O e h m e , Academy of Science of G.D.R., Rostock, G.D.R. Crosslinked polymeric materials have been used frequently as supports for heterogenizing of transition metals. Usually, the properties of the supports influence activity and selectivity of catalysts. We prepared four different polystyrene resins crosslinked with 2% divinylbenzene and functionalized these matrices in the following sequence, obtaining ten differently substituted derivatives 2 and 3: (
~
CH3OCH2CI,(~-CH2CI
1
2
LiPPh2>(~!-CH2PPh
2
3
To obtain information about the properties (e.g. penetration) of the resins we investigated the degree of swelling q in toluene as standard solvent. The degree of swelling of the matrix polymer 1 was found to be dependent on the polymerization process and is changeable by the functionalization from 1 to 2 and from 2 to 3, respectively. The ratio qx/qo (degree of swelling of derivative/degree of swelling of matrix resin) shows a linear correlation with the degree of substitution. Significant deviations could be observed in the case of intraresin reactions, e.g. between phosphinomethyl groups and chloromethyl groups in 3. Some proposals are given for a rational analytic use of the degree of swelling in the characterization of organic supports. To be submitted to
ReactivePolymers.
Polymer-bound Thiamine Models: Polymer Effects on the Catalytic Activity of Polystyrene-bound Thiazolium Salts in the Benzoin Condensation Reaction H . J . v a n d e n B e r g , G . C h a l l a , State University of Groningen, Groningen, The Netherlands, a n d U . K . P a n d i t , University of Amsterdam, Amsterdam, The Netherlands The catalytic activities of polystyrene-bound thiazolium salts ( l a - b ) and their low molar mass analogues have been determined in the condensation reaction of benzaldehyde to benzoin, under standardized reaction conditions. The activity of the soluble polymer (la) was about two times lower than that of its low molar mass counterpart, while the activities of macroporous polymers were three to four times lower than that of the low molar mass model (depending on the degree of functionalisation of the macroporous polymers). The polymer effect was investigated in terms of diffusional effects, local concentration effects and microenvironmental effects. It is shown that the decreased activity
126 of immobilized thiazolium salts is predominantly a result of steric hindrance of the polymer matrix. The insoluble immobilized thiazolium salts could be used repeatedly without loss of catalytic activity, provided that equimolar amounts of cocatalyst (triethylamine) were used. Excess of amine accelerated the benzoin condensation, but decreased the stability of the catalyst.
ta:(~)= Linear Polystyrene Me
Ho~S >
b:(~) = Macroporous Styrene-DVB copolymers
Ct-
Submitted for publication in
Journal of Molecular Catalysis.
An Attempt at Classification of Solid Superacids R o m u a l d B o g o c z e k a n d J o a n n a S u r o w i e c , Technological Institute of Chemical and Food Industry, Wroctaw, Poland The development of liquid superacid chemistry was accompanied by the appearance of a new generation of such acids, i.e., of solid superacids. Their preparation consists in application of polymeric matrices as carriers for systems with increased acidity. So solid superacids can be considered as polymer-supported reagents and catalysts. Measurements of superacidic system acidity with Hammett function H 0 allows to include or not the tested systems in the category of superacids. Most authors suggest using the term superacid only for the systems showing H o < - 12 or H 0 < - 1 5 . At the same time there is a tendency to refer to systems with higher acid strength on solid supports as superacids, without measuring H 0. The systems show, however, catalytic activity in hydrocarbon transformations. Irrespective of the H 0 function, we suggest the following classification of superacidic systems: 1. According to the state of aggregation: liquid and solid. 2. According to the number of components: simple and composite, i.e., multicomponent, usually two- or three-component. 3. According to the acid character of the components: protonic (Br~Snsted), aprotonic (Lewis), and conjugated (BriSnsted and Lewis acid mixtures). Thus, within the group of solid superacids the following systems can be distinguished: Brrnsted, Lewis, and BrSnsted-Lewis systems on inorganic or organic carriers. Moreover, some authors refer to acid systems on the basis of fluoric polymers containing sulfonic groups (e.g. Nation-H) as superacids. Research on superacid systems on organic polymeric carriers is proceeding in three directions: 1. The fixation of a Lewis acid (e.g., A1C13, SbCI 3, SbF5, BF3) to a styrene-divinylbenzene matrix. 2. The preparation of polymeric systems of Brrnsted-Lewis type (e.g., Amberlyst 15 + AIC13). 3. The increase of acidity of conventional polyacids of Bronsted type, e.g., of cation exchange resins with sulfonic groups by fluorination. Publication details not decided.
Phenol Halogenation with the Use of Poly(styrene-divinylbenzene)halogeno-Suifonamides R o m u a l d B o g o c z e k a n d E l ~ b i e t a K o c i o / e k - B a l a w e j d e r , Technological Institute of Chemical and Food Industry, Wroclaw, Poland Phenol in 0.1 molar aqueous solution has been brought into contact with the following macroporous poly(styrene-divinyibenzene)SO2NH2 halogen derivatives in bead form: