[reaction: see text] Stable 4-[2-isopropylidene]-phenol carbocation, IPP cation 1, was generated readily by addition of bisphenol A in concentrated sulfuric acid at ambient temperature, and the cation could be used for facile syntheses of 4-isopropenyl phenol (IPP), IPP dimers, and spiro-bisphenol derivatives.
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http://dx.doi.org/10.1021/ol0493305 | DOI Listing |
Chem Sci
January 2017
Department of Chemistry , University of Cambridge, Lensfield Road , Cambridge CB2 1EW , UK . Email:
Two homochiral building blocks featuring a protected thiol, an alkene and a H-bond recognition unit (phenol or phosphine oxide) have been prepared. Iterative photochemical thiol-ene coupling reactions were used to synthesize oligomers containing 1-4 phosphine oxide and 1-4 phenol recognition sites. Length-complementary H-bond donor and H-bond acceptor oligomers were found to form stable duplexes in toluene.
View Article and Find Full Text PDFPhys Chem Chem Phys
May 2009
Université de Pau et des Pays de l'Adour, IPREM CNRS UMR 5254, Helioparc Pau Pyrénées, 2 avenue du président Angot, 64053, Pau cedex 9, France.
This paper presents the preparation and characterization of hybrid hydrotalcite-type layered double hydroxides (Zn1-xAlx(OH)2HBSx.nH2O, with x=0.33) where HBS is the 4-phenol sulfonate, with a detailed analysis of the grafting process of this organic entity onto the host lattice.
View Article and Find Full Text PDFJ Phys Chem B
February 2008
Beijing National Laboratory for Molecular Science, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
Puerarin, a C-glycoside of daidzein, forms upon direct photoexcitation in acetonitrile an excited-state with a lifetime of 4.2 micros assigned by oxygen quenching and sensitized formation of triplet zeaxanthin as a triplet and phenoxyl radicals of ms lifetime insensitive to oxygen and with spin density delocalized over the ACB isoflavonoid ring system, [ACB]*, as shown by laser flash photolysis and theoretical spin density calculations. Photoexcitation of A-ring 7-phenolate puerarin yields a [AC]* radical, which converts into the [ACB]* radical with a rate constant of 3.
View Article and Find Full Text PDFClin Exp Allergy
January 2003
Centre for Biochemical Technology, University of Delhi, Delhi, India.
Background: Allergen extracts are unstable, heat labile or susceptible to proteases. Stability of allergen extracts is important for proper diagnosis and therapy of allergic disorders.
Objective: The present study was undertaken to determine the preservation and stabilization conditions of Imperata cylindrica (Ic) grass pollen extract.
Clin Exp Allergy
April 1996
Department of Dermatology, Helsinki University Central Hospital, Finland.
Background: Ingested cereals and inhaled cereal dusts can cause IgE-mediated allergy. Testing for these allergies yields variable, often undependable results, which could be due to the use of unsuitable or degraded testing materials.
Objective: We studied the effect of storage media, time and temperature on the stability of protein allergens extracted from wheat, rye, barley and oats flour.
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