Polymers from intermediates obtained from hydrogen cyanide

The recent demonstration of an easy synthesis of diiminosuccinonitrile (DISN) from hydrogen cyanide and cyanogen, the reduction of DISN to diaminomaleonitrile (DAMN), and the use of these compounds to form difunctional heterocycles has made several new polyamide intermediates accessible. The 1- and 2-methyl-1,2,3-triazole-4,5-dicarbonyl chlorides have been polymerized interfacially to form high-melting polyamides of good heat stability. Interfacial polymerization of 1-methylimidazole-4,5-dicarbonyl chloride and trans-2,5-dimethylpiperazine has given a polyamide that is water-soluble. The 2,6- and 2,3-pyrazinedicarbonyl chlorides have been similarly converted to high-melting polyamides. 2,6-Dicyano-3,5-dipiperazinylpyrazine has been prepared from tetracyanopyrazine and piperazine and reacted with toluene diisocyanate to form a strong, stiff polyurea. Polyamides were also made from 2,3-diaminoquinoxaline, 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, and DAMN.     

Fish attractants from marine invertebrates: Arcamine from Arca Zebra and strombine from Strombus Gigas

The isolation and characterisation of two fish attractants, a new dipeptide (Arcamine, hypotauryl-2-carboxyglycine),1 and Strombine (C-methyl-imino diacetic acid),2 are described.     

Alkaloids from the Tunicate Polycarpa aurata from Chuuk Atoll

Two new alkaloids, polycarpine (1) and N,N-didesmethylgrossularine-1 (4), have been isolated from extracts of the ascidian Polycarpa aurata collected in Chuuk, Federated States of Micronesia. Three degradation products of 1 were also isolated. The structures of 1, 2, and 4 were determined by X-ray crystallography. The dimeric disulfide 1 inhibited the enzyme inosine monophosphate dehydrogenase, but the inhibition could be reversed by addition of excess dithiothreitol suggesting that 1 reacts with sulfhydryl groups on the enzyme.     

Stereocomplex Formation from Enantiomeric Polyamides Derived from Tartaric Acid

Summary: The formation of stereocomplexes from the pair of enantiomorphs of the chiral polyamide poly(hexamethylene di‐O‐methyl tartaramide) was investigated for a variety of experimental conditions. DSC and X‐ray diffraction data evidenced that efficiency in enantiomeric association is highly sensitive to the procedure used for preparing the complex. A comparative isothermal crystallization study revealed that the stereocomplex crystallized from the melt at a rate lower than the enantiomerically pure components. The radial growth of individual spherulites was also delayed in the crystallization of the complex. No evidence of stereocoupling was detected for other poly(alkylene di‐O‐methyl tartaramide)s with the alkylene unit length different from six. It was concluded that molecular interlocking of hydrogen bonds in the enantiomeric pair is highly selective in this family of polymers.

Spherulitic growth at 200 °C from the melt.     

Cytotoxic diterpenoids from Podocarpus madagascariensis from the Madagascar rainforest

Bioassay-directed fractionation of an extract of the root and bark of Podocarpus madagascariensis resulted in the isolation of a new totarol diterpenoid (1) in addition to the three known cytotoxic diterpenoids 19-hydroxytotarol (2), totaradiol (3), and 4beta-carboxy-19-nor-totarol (4). The structure of the new compound 1 was established as methyl-13-hydroxy-14-isopropyl-9(11),12,14(8)-podocarpatriene-19-oate on the basis of 1D and 2D NMR spectroscopic interpretation and methylation of 4. All the compounds exhibited cytotoxic activity against the A2780 ovarian cancer cell line.     

Synthesis of isoxazolines from nitrile N-oxides generated from nitroalkenes

In this review, information on the production of isoxazolines and condensed isoxazoline systems by the intramolecular 1,3-bipolar cycloaddition of unsaturated nitrile N-oxides generated in situ from nonconjugated nitroalkenes is generalized and systematized. The isoxazoline derivatives formed as the result of these reactions are promising synthons in the synthesis of various natural compounds and their analogues.Krakow Polytechnic Institute, Poland. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 291–305, May–August, 1992.     

Engineers are from PDMS-land, Biologists are from Polystyrenia

As the integration of microfluidics into cell biology research proceeds at an ever-increasing pace, a critical question for those working at the interface of both disciplines is which device material to use for a given application. While PDMS and soft lithography methods offer the engineer rapid prototyping capabilities, PDMS as a material has characteristics that have known adverse effects on cell-based experiments. In contrast, while polystyrene (PS), the most commonly used thermoplastic for laboratory cultureware, has provided decades of grounded and validated research conclusions in cell behavior and function, PS as a material has posed significant challenges in microfabrication. These competing issues have forced microfluidics engineers and biologists to make compromises in how they approach specific research questions, and furthermore, have attenuated the impact of microfluidics on biological research. In this review, we provide a comparison of the attributes of PDMS and PS, and discuss reasons for their popularity in their respective fields. We provide a critical evaluation of the strengths and limitations of PDMS and PS in relation to the advancement and future impact on microfluidic cell-based studies and applications. We believe that engineers have a responsibility to overcome any challenges associated with microfabrication, whether with PS or other materials, and that engineers should provide options and solutions that assist biologists in their experimental design. Our goal is not to advocate for any specific material, but provide guidelines for researchers who desire to choose the most suitable material for their application, and suggest important research directions for engineers working at the interface between microfabrication technology and biological application.     

Electrochemical deposition of platinoids from ammonia-nitrate eluates from silver refining

The differences in the electrochemical behavior of palladium and platinum in the individual and mixed ammonia-nitrate eluates from silver refining, insufficient for selective electrowinning of palladium, were revealed and studied. The possibility of obtaining the binary alloys of metals from the platinum group was shown. A method for the preparation of platinized titanium anodes by platinum electrodeposition on the titanium cathodes from palladium-depleted electrolytes of refining at OAO Uralelektromed’ was suggested.     

Small angle X-ray scattering from amorphous polymers arising from heterogeneities

Summary The small angle X-ray scattering of glassy polymers (PET, PC, PVC, PMMA) and of polymer melts (PE) was studied. The dependence of the intensity scattered at small angles on the sample treatment suggests that neither the inherent structure of the pure polymer phase nor microholes are the origin of the scattering. In agreement with all experimental facts the scattering can be attributed to foreign particles such as for instance stabilizers in the polymer matrix. The consequence of this result is discussed with respect to the nodular structure of the amorphous phase and with respect to structural models of the amorphous phase. The nodular structure is not related to regions of different densities within the pure amorphous phase.The small angle X-ray scattering can be used to characterize the microscopic and macroscopic distribution of additives in polymer samples.

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Zusammenfassung Es wurden Röntgenkleinwinkeluntersuchungen an glasig erstarrten Polymeren (PÄT, PC, PVC, PMMA) und an Polymerschmelzen vorgenommen (PÄ). Die Abhängigkeit der bei kleinen Winkeln beobachteten Streuung von der Probenbehandlung weist darauf hin, daß weder die innere Struktur der amorphen Phase noch Mikrolöcher die Ursache für die Streuung sein können. In Übereinstimmung mit allen Ergebnissen wird die Streuung Fremdpartikeln wie z. B. Stabilisatoren in der Polymermatrix zugeschrieben. Die Folgerungen, die sich hieraus ergeben, werden hinsichtlich der Körnerstruktur der amorphen Phase und der Strukturmodelle diskutiert. Die Körnerstruktur kann nicht durch Bereiche unterschiedlicher Dichte in der amorphen Phase erklärt werden.Die Röntgenkleinwinkelstreuung kann zur Charakterisierung der makroskopischen und der mikroskopischen Verteilung der Zusätze im Polymeren herangezogen werden.

     

New azaphilones from Chaetomium globosum isolated from the built environment

A strain of Chaetomium globosum (DAOM 240359) was isolated from an indoor air sample in Ottawa, Ontario, Canada. When fermented in liquid culture, this strain produced a number of known metabolites including chaetoglobosins A (6), C, and F (7), chaetomugilin D (5), chaetoviridin A (4), and three new nitrogenous azaphilones; 4′-epi-N-2-hydroxyethyl-azachaetoviridin A (1), N-2-butyric-azochaetoviridin E (2), and isochromophilone XIII (3). The structures were elucidated by spectroscopic analysis including; HRMS, 1D and 2D NMR, UV, and ORD. Compounds 2–7 were antimicrobial when tested using quantitative growth inhibition assays.     

Heterocycles from substituted amides. VII Oxazoles from 2-isocyanoacetamides

Certain heretofore unknown tertiary α-isocyanacetanilides 1 are reported for the first time, prepared by methods necessarily different from those employed to prepare the previously cited aliphatic α-isocyano-acetamides 2 . Like 2, 1 has been shown to readily undergo dialkylation with alkyl halides. Moreover, 1 also gives rise to oxazole and oxazoline derivatives upon reaction with acyl halides and aldehydes, respectively, resembling the similarly activated α-isocyano esters and sulfones. Further, in a demonstrable ring-chain tautomeric equilibration, apparently restricted to tertiary amides, 1 readily cyclizes, providing the only known synthesis of 5-amino-2,4-unsubstituted oxazoles 3 . In other examples 4-chloro and 4-alkyl-5-amino-oxazoles are produced. The materials and reactions are characterized, and compared with previous related studies.     

Products from dehydration of dicarboxylic acids derived from anthranilic acid

Treatment of N-(carboxymethyl)-anthranilic acids 1 with several dehydrating agents, gave the cyclic ortho amides 6, or the 7-membered anhydrides 7. After reaction of N-(carboxymethyl)-anthranilic acid (1a) with acetic anhydride, a diacetylated fused diketopiperazine indole dimer (18) could be isolated. Dehydrations of 2,2'-iminobis-benzoic acid led to the corresponding cyclic ortho amides 23. The dynamic behaviour of some of these compounds, and their precursors, was studied.