Biotransformation of ent-beyerenes with mucor plumbeus

Indexación: Web of Science; Scielo.ABSTRACT The microbiological transformation of ent-beyer-15-en-18-ol 1 and ent-beyer-15-en-19-ol 2, using Mucorplumbeus, resulted in hydroxylated products. After nine days of incubation, 15β,16β-epoxide-ent-beyeran-7β,18-diol 3, ent-beyer-15-en-7p,19-diol 4 and 15β,16β-epoxide-ent-beyeran-7β,19-diol 5 were isolated. The metabolites were identified by spectroscopic methods. Key Words:http://ref.scielo.org/47kx2

HET acid based oligoesters – TGA/FTIR studies

One of the important reactive halogenated dicarboxylic acids used in the synthesis of flame retardant unsaturated polyester resins is 1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (HET acid). In the present investigation four different oligoesters are synthesized using HET acid as the diacid component and 1,2-ethane diol, 1,2-propane diol, 1,3-propane diol and 1,4-butane diol as the aliphatic diols. Melt condensation technique in vacuum is used for the synthesis of the oligoesters. The number average molecular weights of the oligoesters are determined using end group analysis. The degree of polymerization is estimated to be 3–5. The structural characterization is done using FTIR and NMR (1H and 13C) techniques. In the present investigation, TGA-FTIR studies for the different oligoesters are carried out in nitrogen atmosphere. The materials are heated from ambient to 600 °C at a heating rate of 20 °C/min. The main volatile products identified are CO, HCl, H2O, CO2, hexachlorocyclopentadiene and HET acid/anhydride. The evolution profile of these materials with respect to the structure of the oligoesters is discussed in detail and presented. The importance of β-hydrogens in the diol component and the plausible mechanism for the flame retardant behavior of these oligoesters are presented

Preparation of highly fluorinated polyurethanes

New polyurethanes, formed from a reaction of a prepolymer diol and a perfluorinated diisocyanate, are nonflammable and possess high corrosion resistance and good low temperature flexibility. Polymer hardness increases rapidly with increasing ratio of diisocaynate to diol, but its glass transition temperature is not adversely affected

Immobilisation of enzymes to Perloza cellulose resin : this thesis was presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry at Massey University /

The studies reported in this thesis describe the use of Perloza™ beaded cellulose resin as a solid support for enzyme immobilisation via covalent binding. The aim of the project was to extend the uses for Perloza™ and to compare the use of well known solid support activation chemistries with a recently developed one for Perloza™. Preparations such as these have potential industrial uses. Three attachment chemistries were studied. The first activation employed 1,1-carbodiimidazole (CDI) then direct attachment of enzyme. The second again used CDI activation followed by attachment of a 6-aminocaproic acid spacer arm and then the enzyme. The final method used was attachment of a diol and subsequent oxidation to an aldehyde. The diol/aldehyde method had the advantage over the CDI methods of being based on aqueous chemistries. The two CDI based methods require extensive use of dry organic solvents. The enzymes investigated in this study were trypsin, chymotrypsin. α-amylase, horseradish peroxidase (HRPO) and alcohol dehydrogenase (ADH). Trypsin was immobilised successtully by all three chemistries. All preparations retained significant activity after immobilisation at room temperature as judged by the chromogenic substrate specific for trypsin N-α-benzoyl-DL-arginine-p-nitroanilide.HC1 (BAPNA). Measurable activity was retained in different studies from between 2 to 7 days at 60°C. The activity of immobilised trypsin with a synthetic peptide substrate was comparable to the activity of free trypsin with the same substrate. Chymotrypsin was also successfully immobilised using all three chemistries. Each preparation showed significant retention of activity after immobilisation as judged by the chromogentic substrate N-glutaryl-L.-phenylalanine-p-nitroanilide (GAPNA). Stabilisation to heating at 60°C was less successful than with trypsin but significant activity was still retained for between 3 and 6 hours. The activity of immobilised preparations with a peptide substrate was comparable to free chymotrypsin. α-Amylase, horseradish peroxidase and alcohol dehydrogenase were studied less extensively than trypsin and chymotrypsin. Nevertheless all three enzymes were successfully immobilised onto Perloza™-CDI-ACA and Perloza™-Diol/Aldehyde. Difficulty was encountered in achieving significant levels of any enzyme immobilisation to Perloza™-CDI for all three enzymes. Subsequent activity assays showed HRPO and α-amylase retained significant activity on all three resin preparations. ADH showed no measurable activity on Perloza™-CDI and very little activity on Perloza™- CDI-ACA and Perloza™-Diol/Aldehyde. Investigations have shown that enzymes can be immobilised on Perloza™ with retention of significant amounts of normal activity at room temperature and improved stability compared with free enzyme at high temperature. Comparisons of the CDI activations with the diol/aldeyde chemistry showed better performance by the latter in trypsin immobilisation and similar performance for chymotrypsin immobilisation. Horseradish peroxidase and ™-amylase were successfully immobilised using CDI/ACA and diol/aldehyde chemistries with the CDI/ACA giving higher initial specific activities than the diol/aldehyde preparation. Alcohol dehydrogenase was also successfully immobilised but gave no measurable activity

In situ self cross-linking of polyvinyl alcohol battery separators

A battery separator was produced from a polyvinyl alcohol sheet structure which was subjected to an in situ, self crosslinking process by selective oxidation of the 1,2 diol units present in the polyvinyl alcohol sheet structure. The 1,2 diol units were cleaved to form aldehyde end groups which subsequently crosslink through acetalization of the 1,3 diol units of the polyvinyl alcohol. Selective oxidation was achieved using a solution of a suitable oxidizing agent such as periodic acid or lead tetraacetate

A low-toxicity method for the separation of lanosterol and dihydrolanosterol from commercial mixtures

We describe an inexpensive, low-toxicity and high-yielding method for the production of pure lanosterol and dihydrolanosterol from the commercially available mixture. Optimum conditions are presented for the one-pot production of the intermediate 24,25 vicinal diol of lanosterol acetate (via either epoxidation or hydroxyhalogenation) which is readily separated from the unreacted dihydrolanosterol acetate. The lanosterol diol can then be converted to pure (>97%) lanosterol. Hypophosphorous acid was used for both the conversion of the epoxide to the diol, and as a catalyst for the hydroxyhalogenation by N-halosuccinimides of the olefinic bond

Synthesis and NMR structure determination of new linear geranylphenols by direct geranylation of activated phenols.

Indexación: Web of Science; ScieloThe known geranylhydroquinone 2, geranylorcinol 4 and the derivative (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-methylbenzene-1,3-diol 5, were prepared by Electrophilic Aromatic Substitution (EAS) reactions between the corresponding phenol derivatives containing electron-donor subtituents and geraniol using BF3XOEt2 as a catalyst. In addition, spectroscopic NMR information for 4 and 5 is complemented. Furthermore, the new (E)-2-(3,7-dimethylocta-2,6-dienyl) benzene-1,3,5-triol (geranylphloroglucinol) 13, (E)-2-(3,7-dimethylocta-2,6-dienyl)-1,3,5-trimethoxybenzene 14, (E)-2-(3,7-dimethylocta-2,6-dienyl)-6-methoxyphenol 15, (E)-3-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 16, (E)-5-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 17, (E)-4-(3,7-dimethylocta-2,6-dienyl)benzene-1,3-diol 18, (E)-3-(3,7-dimethylocta-2,6-dienyl)benzene-1,2-diol 19, (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-isopropyl-2-methylphenol 20, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-3-methylphenol 21, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-5-methylphenol 22, and(E)-2-tert-butyl-4-(3,7-dimethylocta-2,6-dienyl)-5-methylphenol 23 were also prepared with this synthesis strategy. All the synthesized compounds were fully characterized and their structures were established by IR, MS and mainly NMR spectroscopic dates.http://ref.scielo.org/3cj5t

Alcohols utilization as non - freezing heat transfer liquids

Tato bakalářská práce se zabývá alkoholy využívanými v teplonosných nemrznoucích směsích. Byly porovnávány alkoholy methanol, ethanol, ethan-1,2-diol, propan-1,2-diol a propan-1,3-diol. Látky byly zkoumány hlavně z toxikologického hlediska a negativního dopadu na zdraví člověka. Nejtoxičtější látkou byl určen ethan-1,2-diol. Nejvíce využívanou látkou na trhu je propan-1,2-diol, který je netoxický.This bachelor´s thesis deals with the alcohols used by the non-freezing heat transfer fluid. Were compared alcohols methanol, ethanol, ethane-1,2-diol, propane-1,2-diol and propane-1,3-diol. The substances were examined mainly from the toxicological point of view and negative impacts on human health. Toxic substance was determined by ethane-1,2-diol. Propane-1,2-diol is the most used substance in the market which is non-toxic.

Pd-catalyzed enantioselective aerobic oxidation of secondary alcohols: Applications to the total synthesis of alkaloids

Enantioselective syntheses of the alkaloids (-)-aurantioclavine, (+)-amurensinine, (-)-lobeline, and (-)- and (+)-sedamine are described. The syntheses demonstrate the effectiveness of the Pd-catalyzed asymmetric oxidation of secondary alcohols in diverse contexts and the ability of this methodology to set the absolute configuration of multiple stereocenters in a single operation. The utility of an aryne C-C insertion reaction in accessing complex polycyclic frameworks is also described

Competitive formation of spiro and ansa derivatives in the reactions of tetrafluorobutane-1,4-diol with hexachlorocyclotriphosphazene: a comparison with butane-1,4-diol

Reaction of hexachlorocyclotriphosphazene, N3P3Cl6 (1), in two stoichiometries (1:1.2 and 1:3) with the sodium derivative of the fluorinated diol, 2,2,3,3-tetrafluorobutane-1,4-diol, (2), in THF solution at room temperature afforded six products, whose structures have been characterized by X-ray crystallography and 1H, 19F and 31P NMR spectroscopy: the mono-spiro compound, N3P3Cl4(OCH2CF2CF2CH2O), (3), its ansa isomer, (4), a di-spiro derivative N3P3Cl2(OCH2CF2CF2CH2O)2, (5), its spiro-ansa (6) and non-gem cis bis-ansa (7) isomers and a tri-spiro compound N3P3(OCH2CF2CF2CH2O)3, (8). The tri-spiro derivative (8) was also formed in the reaction of the ansa compound (4) with diol (2) in a 1:3 ratio in THF at room temperature. The reactions of (1) with step-wise additions of (2) were also investigated at low temperature (-780C) to give the same range of products as at room temperature. The results of all reactions are compared with previous work on the reactions of (1) with butane-1,4-diol/pyridine mixtures and with the reaction of hexafluorocyclotriphosphazene, N3P3F6 (9), with the silyl derivative of the diol (2), (Me3SiOCH2CF2)2, in a 1:0.4 mole ratio in the same solvent, THF