Search Results

You are looking at 1 - 10 of 32 items :

  • "covalent fixation" x
Clear All


Vinyl ester of 4-carboxyphenylboronic acid has been synthesized and tested as reactive reagent for permanent fixation of boron in wood based on an improved approach described previously. The essence of the method is a covalent incorporation of the boron compound via transesterification between wood hydroxyl groups and vinyl ester containing boron. The synthesis of this vinyl ester was accomplished by exchange reaction of vinyl acetate with 4-carboxyphenylboronic acid. The obtained vinyl ester of carboxyphenylboronic acid was characterized by FTIR and 1H-, and 13C-NMR spectroscopy. The covalent fixation of boron to wood’s hydroxyl groups was achieved through potassium carbonate (K2CO3) catalyzed transesterification of the vinyl ester containing boron. The transesterification was confirmed by weight percentage gain (WPG) calculation, curcumin staining, FTIR, and 13C CP-MAS NMR spectroscopy. The efficiency of the reaction improved with increasing temperature and reaction time.

Biol. Chem. Hoppe-Seyler Vol. 367, pp. 969-980, September 1986 Covalent Fixation of NAD® to Dehydrogenases and Properties of the Modified Enzymes Heinz-Günter SCHÄFER , Tobias JACOBI, Heidi EICHHORN and Christoph WOENCKHAUS Zentrum der Biologischen Chemie, Abteilung Enzymologie Klinikum der Universität Frankfurt (Received 17 April 1986) Dedicated to Prof. Dr. G. Pfleiderer on the occasion of his 65th birthday Summary: Starting from 6-chloropurine riboside and NAD®, different reactive analogues of NAD® have been obtained by introducing dia- zoniumaryl or aromatic

presented wood modification reactions yielded weight percent gain values from 14% to 31% on beech wood, spruce wood, and pine sap- wood meal (approximately 500 mm in diameter) or pine sapwood veneer chips. The modified meals and chips were analysed by IR spectroscopy. Keywords: boron; covalent fixation; leachability; synthe- sis; wood preservatives. Introduction Natural wood is durable only when it is shielded from air, UV light, or other environmental influences including bio- logical attack. However, natural deterioration is difficult to avoid under outdoor conditions

, whereas the C-N stretching signal only intensifies the broad C-O stretching signals at around 1270 cm -1 . In case of the boron- and silyl-modified wood, in addition to aromatic ring deformation vibrations in the region from 800 to 700 cm -1 , characteristic signals appear between 850 and 700 cm -1 , which are assigned to vibrations involving the heteroatoms B and Si as discussed previously (Namyslo and Kaufmann 2009), e.g., the C-H rocking of SiCH 3 at 837 cm -1 and the B-C stretching vibration at 711 cm -1 . The expected durable covalent fixation proved itself to be

showed an increase of mass loss, as well as an increase of the temperature and of the residue. Among these findings, the best results were obtained with the phosphorus bearing 1,3,2-dioxaphospholane 2-oxide and T3P ® which led to similar fire resistance of the modified wood. All in all, upon covalent fixation of appropriate orpanophosphorus and organoboron compounds wood samples were apparently protected against fire via covalent modification with corresponding 1 H -benzotriazole activated carboxylic acids and T3P ® . Acknowledgments All the authors have accepted

. Chem. Rev. 53:191–261. 10.1021/cr60165a003 Jaffé H.H. 1953 A reexamination of the Hammett equation Chem. Rev. 53 191 261 Jebrane, M., Heinmaa, I. (2015) Covalent fixation of boron in wood through transesterification with vinyl ester of carboxyphenylboronic acid. Holzforschung 70:577–583. Jebrane M. Heinmaa I. 2015 Covalent fixation of boron in wood through transesterification with vinyl ester of carboxyphenylboronic acid Holzforschung 70 577 583 Kaldun, C., Dahle, S., Maus-Friedrichs, W., Namyslo, J.C., Kaufmann, D.E. (2016) Chemical improvement of surfaces. Part 4


One aim of this work was the chemical modification of surfaces of Scots pine (Pinus sylvestris L.) sapwood veneer chips by covalently bonded substances for improved hydrophobicity. The durable attachment of organosilyl moieties to the surface was in focus. Several benzotriazolyl-activated p-silylated benzoic acid derivatives were applied to the esterification of OH groups at different temperatures and reaction times. The reactions resulted in weight percent gains from 8% to 43% and corresponding quantities of covalently bonded organomaterials of 0.3–2.1 mmol g-1 wood. The hydrophobicity was significantly increased as indicated by contact angles from 121° to 142°. All modified wood samples were analyzed by attenuated total reflection-infrared, contact angle measurements, and X-ray photoelectron spectroscopy.


A recently developed esterification method in our laboratory was applied to permanent hydrophobization of wood surfaces. Specifically, the covalent attachment of fluoroorganyl substituents to wood hydroxy groups via benzotriazolyl-activated, substituted benzoic acids was in focus. Weight percent gain values from 10% to 28% were obtained on Scots pine (Pinus sylvestris) sapwood veneer chips. It proved feasible to lower the temperature for wood modification from 150°C to 120°C, or even to 70°C so that thermal decomposition of wood during modification can be neglected. The modified chips were analyzed by attenuated total reflection – infrared and X-ray photoelectron spectroscopy. Covalent attachment of the fluorobenzoic acids led to a very high, permanent hydrophobicity of the wood surface, documented by outstanding contact angles of up to 143°.


desorption processes 547 Marjan Sedighi Gilani, Jürg Neuenschwander, Markus Heeb, Roman Furrer, Sergio J. Sanabria, Berend C. Stoel and Francis Willis Mathew Robert Schwarze Influence of incubation time on the vibration and mechanic properties of mycowood 557 Jinghao Li, John F. Hunt, Shaoqin Gong and Zhiyong Cai Fatigue behavior of wood-fiber-based tri-axial engineered sandwich composite panels (ESCP) 567 Mohamed Jebrane and Ivo Heinmaa Covalent fixation of boron in wood through transesterification with vinyl ester of carboxyphenylboronic acid 577 Grant T

Biotechnol Bioeng 10970290 Electrochemical measurements with glucose oxidase immobilized in polyacrylamide gel: Constant current voltametry 19 1971 3 250 522 10.1016/0005-2744(71)90252-X Wykes J.R. Dunnill P. Lilly M.D. Biochimica et Biophysica Acta (BBA) - Enzymology Biochimica et Biophysica Acta (BBA) - Enzymology 00052744 Immobilisation of α-amylase by attachment to soluble support materials 20 1971 2 18 254 10.1016/0014-5793(71)80457-X Vretblad Per Axén Rolf FEBS Letters FEBS Letters 00145793 Covalent fixation of pepsin to agarose derivatives 21 1970 2 136 325 10