Synthesis of poly[(silanylene)thiophene]s

Poly[(silanylene)thiopene]s, copolymers with alternating thiophene, 2,2-bithiophene, or 2,2:5,5-terthiophene and mono-, di-, or tetrasilanylene units, were prepared by condensation of the dilithium salts of the thiophenes or the bis(2-thienyl)silanes with ,-dichlorosilanes in diethylether. The polymers were characterized with¹H,¹³C, and²⁹Si NMR, UV, IR, GPC, TGA, and elemental analyses. UV absorption maxima of these polymers all show a red shift with increasing length of the polymer backbone, suggesting that conjugation occurs through the combined -Si and -thiophene backbone.This paper was presented at the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Chemical modification of copoly(methylsilylene/1,4-phenylene) by Pt-catalyzed hydrosilation reactions with functionally substituted alkenes

Copoly(methyl-3-biphenoxypropylsilylene 1,4-phenylene), copoly(methyl-3-cyanopropylsilylene 1,4-phenylene), copoly(methyl-3-ethoxypropylsilylene 1,4-phenylene), copoly(methyl-3-phenoxypropylsilylene 1,4-phenylene), and copoly(methyl-4,7,10,13-tetraoxatetradecanylsilylene 1,4-phenylene) have been prepared by platinum-catalyzed hydrosilation graft reactions between poly (methylsilylene 1,4-phenylene) and appropriate functionally substituted alkenes. These polymers have been characterized by¹H,¹³C, and²⁹Si NMR as well as by FT-IR and UV-vis spectroscopy. The molecular weight distribution of these polymers has been determined by gel permeation chromatography (GPC), and their glass transition temperatures (T _e) by DSC.     

Geographic variation of natural products of tropical nudibranch Asteronotus cespitosus

Extracts of the dorid nudibranch Asteronotus cespitosus from two geographically separate regions of Australia and from the Philippines were compared using thin-layer, high-performance liquid and gas chromatography and ¹H NMR analysis. Halogenated metabolites were detected in all mollusk specimens. The major component detected in digestive tissue of specimens from the Great Barrier Reef in northeastern Australia was 4,6-dibromo-2-(2,4-dibromophenoxy)phenol (1), with minor amounts of 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol (2). In a specimen collected from northwestern Australia, only 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol was found. The specimen from the Philippines contained 2,3,4,5-tetrabromo-6-(2-bromophenoxy)phenol (3) together with a novel chlorinated pyrrolidone (4). In addition, the sesquiterpenes dehydroherbadysidolide (5) and spirodysin (6) were detected in the digestive organs and mantle tissue of the nudibranchs from the Great Barrier Reef and from the Philippines, whereas these chemicals were not found in the specimen from northwestern Australia. All of the chemicals (1-3,5, and 6) have previously been isolated from the sponge Dysidea herbacea, as have chlorinated metabolites related to 4. This is the first time the characteristic halogenated metabolites that typify Dysidea herbacea have been reported from a carnivorous mollusk, which implies a dietary origin as opposed to de novo synthesis.     

The electrochemical properties of polyaniline derivatives: poly(4,4′-diphenylamine methylenes) and poly(4,4′-diphenylimine methines)

Summary The electrochemical properties of poly(4,4-diphenylamine methylenes) and poly(4,4-diphenylimine methines) were investigated by cyclic voltammetry. A dehydrogenation reaction occured when poly(4,4-diphenylamine methylenes) underwent a electrochemical reaction and transformed to poly(4,4-diphenylimine methines). The fully oxidized poly(4,4-diphenylimine methines) had the electrochemical band gaps of 1.60–1.72 eV, which were found to significantly smaller than those of the fully reduced poly(4,4-diphenylamine methylenes).     

Synthesis and polymerization of 2-(β-N-3′-halogencarbazolylethyl)-2-oxazolines

Summary The synthesis of three novel oxazoline monomers,all of which contain 3-halogen substituted carbazolyl groups [i.e., 2-(-N-3 chlorocarbazolylethyl)-2-oxazoline, 2-(-N-3 bromocarbazolylethyl)-2-oxazoline and 2-(-N-3 iodocarbazolylethyl)-2-oxazoline]and their polymerization is described.     

Thermoplastic elastomers by hydrogen bonding

Summary Poly(butadienes) were modified by an ene-reaction using 4-phenyl-1, 2,4-triazoline-3,5-dione (1) 3-nitro-4-hydroxyphenyl-1, 2,4-triazoline-3,5-dione (2) and 4-hydroxyphenyl1, 2,4-triazoline-3,5-dione (3). The resulting hydrogen bond complexes between urazole groups act as thermoreversible crosslinks and alter the melt rheological behaviour. While dimeric chelate-like complexes are formed in polymers modified with 1 or 2, a three dimensional structure of hydrogen bond complexes is formed if 3 is used as the modifying agent. The thermorheologically complex behaviour of the latter material is interpreted by structural changes in the three dimensional structure with temperature.     

Female-produced oviposition deterrents of the cigarette beetle,Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

Oviposition deterrents of the cigarette beetle,Lasioderma serricorne, were isolated from its adult body extract and found to be identical to (2S,3R,1'S)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l-methyl-2-oxobutyl)-4H-pyran-4-one (-serricorone) and its lR-epimer (-serricorone) by spectroscopic evidence. Serricorone was previously found as one of the minor sex pheromone components of the same insect, and hence indicating bi-functional nature. The presence of two isomers in the body was proved by careful treatment. Each of them exhibited the same level of oviposition deterring activity, which was less potent than the crude body extract at an increased concentration.     

Syntheses and properties of polyimides based on bis(p-aminophenoxy)biphenyls

Three biphenyl unit-containing diamines,4,4-bis(p-aminophenoxy)biphenyl (III_a), 2,2-bis(p-aminophenoxy)biphenyl (III_b), and 3,3,5,5-tetramethyl-4,4-bis(p-aminophenoxy)biphenyl (III_c), were prepared by the chlorodisplacement ofp-chloronitrobenzene with 4,4-biphenol (I_a), 2,2-biphenol (I_b), and 3,3,5,5-tetramethyl-4,4-biphenol (I_c), respectively, giving the corresponding bis(nitrophenoxy) compounds II_a-c, followed by catalytic reduction with palladium (Pd) and hydrazine. Three series of polyimidesp-PI,o-PI, and Me-PI were prepared from diamines III_a-c and aromatic tetracarboxylic dianhydrides via a two-stage procedure that included ring-opening polyaddition to give poly(amic acid)s followed by thermal cyclodehydration to polyimides. The resultant three series of poly(amic acid)s had inherent viscosities of 1.09–2.83, 0.78–1.93, and 1.55–3.09 dL/g, respectively. Almost all the poly(amic acid)s could be solution-cast and thermally converted into transparent, flexible, and tough polyimide films. All the polyimides were characterized by solubility, tensile test, wide-angle X-ray scattering measurements, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Effects of the structures of aromatic diamines and dianhydrides on the properties of polyimides were investigated.     

Inhibition of male response of drugstore beetles to stegobinone by its isomer

Stegobinone, (2S, 3R, 1R)-2,3,-dihy dro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one, the sex pheromone of drugstore beetles (Stegobium paniceum L.), elicited the pheromonal response from the males of the species in our bioassay system; however, the synthesized diastereomeric mixture of this compound was actually inactive to the males. Although the stegobinone isolated from the beetles of this species had significant activity, its enantiomeric [(±)-2S,3R,1S-] and diatereomeric [(±)-2S,3S,1RS-] isomers were inactive. Adding the (±)-2S,3R,1S isomer to stegobinone significantly reduced the male response. Furthermore, the activity of Stegobinone vanished on keeping it at room temperature for two weeks. In such a stored stegobinone sample, the presence of 2S,3R,1S isomer, the inhibitory component, was confirmed. This isomer might be produced by C-1 epimerization during storage.     

Synthesis of soluble polyarylenes containing alternating 4,4′-(1,1′-binaphthyl) and 4,4′-(3,3′-diphenyl)biphenyl structural units

Summary The synthesis and Ni(0) catalyzed homocoupling polymerization of 4,4-bis[5-(trifluoromethanesulfonyloxy)-2-biphenylyl]-1, 1-binaphthyl (9) are described. This polymerization reaction produces a soluble polyarylene containing alternating 4,4-(1,1-binaphthyl) and 4,4-(3,3-diphenyl)biphenyl structural units.     

Stereochemical inversion of pyrrolizidine alkaloids byMechanitis polymnia (Lepidoptera: Nymphalidae: Ithomiinae): Specificity and evolutionary significance

Pyrrolizidine alkaloids (PAs), acquired by adults or larvae of Danainae and Ithomiinae butterflies and Arctiidae moths from plants, protect these lepidopterans against predators and are biosynthetic precursors of male sex pheromones. The investigation of PAs in many species of wild-caught adults of Ithomiinae showed lycopsamine (1) [(7R)-OH, (2S)-OH, (3S)-OH] as the main alkaloid. In incorporation experiments, PA-free (freshly emerged) adults of the ithomiineMechanitis polymnia were fed seven PAs: lycopsamine and four of its known natural stereoisomers—indicine (2) [(7R)-OH, (2R)-OH, (3S)-OH], intermedine (3) [(7R)-OH, (2S)-OH, (3R)-OH], rinderine (4) [(7S)-OH, (2S)-OH, (3R)-OH], and echinatine (5) [(7S)-OH, (2S)-OH, (3S)-OH], and two PAs without the 7-OH: supinine (6) [(2S)-OH, (3R)-OH] and amabiline (7) [(2S)-OH, (3S)-OH]. Males epimerized PAs 3, 4, and 5 mainly to lycopsamine (1). Females fed these same three PAs changed a smaller proportion to lycopsamine; their lesser capacity to modify PAs corresponds to their normal acquisition of already transformed PAs from males during mating rather than through visits of adults to plant sources of PAs. The alkaloids1 and2, both 7R and 3S, were incorporated without or with minimum change by males and females. Feeding experiments with6 and7 (males only) showed an inversion at the 3 center of6 and no change in7. The inversion from 7S to 7R (probably via oxyreduction) may be closely related to the evolution of acquisition of PAs by butterflies and moths. Two hypotheses are discussed: (1) The ancestral butterflies are probably adapted to tolerate, assimilate, and use (7R)-PAs (most common in plants; all widespread 1,2-unsaturated macrocyclic PA diesters show this configuration). The development of (7R)-PA receptors in the butterflies could lead to a specialization on this configuration in two ways: to help find PA plants and to utilize these components in sexual chemical communication. A later appearance of (7S)-PAs in plants could have selected an enzymatic system for the inversion of this chiral center in order to continue producing (7R)-PA-derived pheromones. (2) The inversion would be due to the evolution of a enzyme system specialized in the transport of (7R)-PAs to the integument; the failure of this system to carry (7S)-PAs led to an enzymatic system to invert them to transportable (7R)-PAs. In this case, the 7R configuration is an effect and not a cause of (7R)-PA-derived pheromones. In both hypotheses, the partial inversion of the 3-asymmetric center, when the butterfly was fed intermedine (3), rinderine (4), and supinine (6), could be fortuitous due to the conformation of the molecule and/or the enzymatic system.This paper is part of the doctoral thesis of J.R.T.     

Synthesis of photodegradable polymers by SH-En polyaddition

Summary The polyaddition reaction of the Michael donor 1.2-bis(2-mercaptoethoxy)ethane (Bis-SH) 2 as dithiol to various Michael acceptors such as divinyl sulfone (DVS) 1, N,N-bismaleimido-4,4-diphenylmethane 3, 4,4-(N-maleimido)diphenyliodoniumchloride 4 and diallyl succinate 5 in the presence of tributylamine is described. Polymers were characterized by NMR-spectroscopy, elemental analysis, DSC and TG-analysis. In particular we synthesized a photosensitive polymer with 4,4-(N-maleimido)diphenyliodonium chloride as comonomer, which eliminated analytical amounts of HCl during irradiation.     

Synthesis and characterization of poly(1-sila-cis-pent-3-enes) substituted with pendant pyridinyl groups

Poly[1-methyl-1-[3-(3-pyridinyl)propyl]-1-sila-cis-pent-3-ene], poly[1-phenyl-1-[3-(3-pyridinyl)propyl)-1-sila-cis-pent-3-ene], and poly[1-phenyl-1-(4-pyridinyl)-1-sila-cis-pent-3-ene] were synthesized by the anionic ring-opening polymerization of 1-methyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, 1-phenyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, and 1-phenyl-1-(4-pyridinyl)-1-silacyclopent-3-ene, respectively. These are the first polycarbosilanes which contain heterocyclic pyridine units as side-chain substituents. These polymers were characterized by¹H,¹³C, and²⁹Si NMR as well as by IR and UV spectroscopy. The molecular weight distributions were determined by gel permeation chromatography, glass transition temperatures, by differential seanning calorimetry: (DSC) and thermal behavior, by thermogravimetric analysis. (TGA).     

Synthesis and thermal properties of block copolyetheresters with poly(pentamethylene p,p′-bibenzoate) segments

The block copolyetheresters with hard segments of poly(pentamethylene p,p-bibenzoate) and soft segments of poly (tetramethylene ether) were prepared by melt polycondensation of dimethyl-p,p-bibenzoate, 1,5-pentanediol and poly (tetramethyene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The results by NMR indicate that the polymer composition is determined by the charge molar ratio (x) of PTMEG to dimethyl-p,p-bibenzoate. The thermal transitions of the block copolyetheresters were investigated by DSC in combination with X-ray diffraction and polarized microscopy. Some block copolyetheresters exhibit a monotropic smectic phase due to the presence of the poly (pentamethylene p,p-bibenzoate) segments. As the molar content of PTMEG increases, the average sequence length of the polyester segments decreases, the isotropic-smectic transition temperature and the smectic order decrease accordingly. When x is as high as 0.3, the block copolyetheresters exhibit no liquid crystallinity.     

Shape-selective isopropylation of biphenyl over a highly dealuminated mordenite: effect of propylene pressure

A highly dealuminated H-mordenite (H-M) catalyzed the selective isopropylation of biphenyl to 4,4-diisopropylbiphenyl (4,4-DIPB). The high selectivity is ascribed to the shape-selective catalysis in mordenite pores. The selectivity of 4,4-DIPB decreased during the isopropylation of biphenyl due to isomerization of 4,4-DIPB under low propylene pressure. The increase of propylene pressure suppressed the isomerization in the isopropylation. 4,4-DIPB itself was isomerized over highly dealuminated H-M under low propylene pressure.     

Preparation of Linear π-Conjugated Coordination Polymers Having Ruthenium(II) Complex in the Main Chain

Soluble -conjugated coordination polymers having a ruthenium(II) complex in the main chain were prepared from a soluble metal complex monomer and a bridging ligand via coordination. Refluxing of an ethanol-water suspension containing (4,4-dinonyl-2,2-bipyridyl)Ru(III) with 2,3-bis(2-pyridyl)pyrazine gave the coordination polymer. The resulting polymer was soluble in common organic solvents. The structure was confirmed by uv/vis spectra and gpc analysis.     

Critical solution point and chain dimension of branched-polystyrene solutions

Summary Critical solution point and chain dimension were measured for branched polystyrene(BPS) in solution as a function of molecular weight(M) and compared with those for linear polystyrene(LPS). The critical concentration _c of BPS was quite different from that of LPS at a fixed M, but the same at a fixed overlap-concentration ^*, i.e., plots of _c vs. ^* fall on a single straight line for both BPS and LPS (gf_c ^*). Reduced critical temperature _c defined by gt_c=(–T_c)/ [T_c: critical temperature, : the -temperature] was related to _c as _{c c} ² for BPS, whereas _{c c} for LPS.     

Shape-Selective Alkylation of Biphenyl over H-[Al]-SSZ-31 with Propylene

Isopropylation of biphenyl (BP) over [Al]-SSZ-31, a large-pore, one-dimensional zeolite has been studied. Effects of temperature, pressure and SiO₂/Al₂O₃ ratio were examined. SSZ-31 was found to be an active catalyst in the isopropylation of biphenyl with propylene. The selectivity for 4-isopropylbiphenyl (4-IPBP) and 4,4-diisopropylbiphenyl (4,4-DIPB) was high among isopropylbiphenyl (IPBP) and diisopropylbiphenyl (DIPB) isomers, respectively, indicating SSZ-31 shows shape-selective catalysis. The selectivity for 4,4-DIPB decreased with temperature increase; correspondingly the selectivity for thermodynamically more stable isomers (3,3- and 3,4 DIPB) increased with temperature. The yield of IPBP isomers decreased while that of DIPB isomers increased with temperature increase. Pressure showed less effect on conversion; however, increase in pressure suppresses the isomerization of 4,4-DIPB to 3,3- and 3,4-DIPB. Conversion decreased with increase in SiO₂/Al₂O₃ ratio. At low SiO₂/Al₂O₃ ratio of 136, relatively high triisopropylbiphenyl (TriIPB) isomers were formed in bulk products and their amount decreased with increase in SiO₂/Al₂O₃ ratio.     

Crosslinking reactions with blocked carbodiimides

Summary Bis-4-(1,4-phenylene)-5-phenyl-1,2,3,5-thiaoxadiazole-1-oxide 1, a blocked bifunctional carbodiimide, has been used as a crosslinder for carboxyl functional poly(meth)acrylates. The thermolysis (deblocking) reaction of 1 has been analyzed by FTIR spectroscopy. The crosslinking reaction has been simulated by using monofunctional model compounds. Intermediate compounds detected were thermally instable N-acylurea's decomposing into isocyanates and amides. Also some anhydride formation occurred. The final structure of the crosslinked product and the rates of crosslinking have been analyzed by FTIR and NMR spectroscopy. Modulus-M_c relations of networks based on carbodiimide compared with those based on bisketeneimine indicate thermolysis of crosslinks in the former case.     

Functional polymers

N-Acryl-N,N-dicyclohexylurea and N-methacryl-N,N-dicyclohexylurea have been synthesized. N-Acryl-N,N-dicyclohexylurea was polymerized with azobisisobutyronitrile as the initiator and the copolymerization of these two monomers with styrene and methyl methacrylate was also accomplished. Monomers, polymers, and copolymers were characterized.Part XXXV: O. Vogl, Polimery, in press.