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21.
22.
Bikshandarkoil R. Srinivasan Sunder N. Dhuri Jyoti V. Sawant Christian N?ther Wolfgang Bensch 《Journal of Chemical Sciences》2006,118(2):211-218
The organic diammonium salt N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide dihydrate, (dbtmen)Br2.2H2O (1), was prepared by the reaction of N,N,N′,N′-tetramethyl-ethylenediamine (tmen) with benzyl bromide.1 crystallizes in the triclinic space group
with the following unit cell dimensions for C20H34Br2N2O2 (M = 494.31):a = 8.6672(6) ?,b = 11.7046(8) ?,c = 11.7731(8) ?, α = 76.988(8)°, β = 88.978(8)°, γ= 76.198(8)γ,V= 1129.26(13) ?3, Z=2. Three components, namely the (dbtmen)2+ dication, two bromide anions and two crystal water molecules constitute the structural arrangement of1. H2O molecules are linked to bromide anions via O-H...Br hydrogen bonding interactions resulting in the formation of a four-membered
O2Br2 cyclic dibromide. The O2Br2 units and the dications are arranged as alternating layers extending in the crystallographicbc plane. The arrangement of anions and cations may be viewed as a typical lamellar structure. The crystal water molecules can
be removed by heating 1 at 140°C and the anhydrous dibromide thus formed can be fully rehydrated as evidenced by IR spectra
and X-ray powder patterns.
Dedicated to Prof S Chandrasekaran on the occasion of his 60th birthday 相似文献
23.
The cyclization of o-aminobenzoylhydrazine ( 1a ) and its 5-methyl derivative 1b with four equivalents and with one equivalent of triethyl orthoacetate (TEOA) was studied. 3-Amino-2-methyl-4(3H)-quinazolinone ( 2a ), 3,4-dihydro-2-methyl-5H-1,3,4-benzotriazepin-5-one ( 3a ) and an imino ether derivative of 2a , N-[2-methyl-4-oxo-3(4H)quinazolinyl]ethanimidic acid ethyl ester ( 4a ) were obtained from the reaction of 1a with four equivalents of TEOA. These results were compared with those of Merour [1] who isolated 2a and 3a using the same conditions. When 1a was treated with one equivalent of TEOA, 2a, 3a , and a new product, 2-(5-methyl-1,3,4-oxadiazol-2-yl)benzenamine ( 5a ) were produced, and 4a was not. Similar results were obtained with the reactions of 1b with TEOA. Authentic samples of oxadiazoles 5a and b were prepared by alternate routes. Novel acid-catalyzed rearrangements of benzotriazepinones 3a and b , to mixtures of aminoquinazolinones 2a and b and oxadiazoles 5a and b , respectively, were found. The different relative amounts of aminoquinazolinones 2 and oxadiazoles 5 which were produced from these rearrangements allowed us to choose between two potential mechanisms for these interesting rearrangements. Treatment of 5-nitrobenzoylhydrazine ( 37 ) with four equivalents of TEOA gave three products which were characterized, but did not lead to benzotriazepinone formation. 相似文献
24.
This paper is devoted to a study of the subfactors arising from vertex models constructed out of `biunitary' matrices which happen to be permutation matrices. After a discussion on the computation of the higher relative commutants of the associated subfactor (in the members of the tower of Jones' basic construction), we discuss the principal graphs of these subfactors for small sizes of the vertex model. Of the 18 possibly inequivalent such biunitary matrices when , we compute the principal graphs completely in 15 cases, all of which turn out to be finite. In the last section, we prove that two of the three remaining cases lead to subfactors of infinite depth and discuss their principal graphs.
25.
P. Srihari Dinesh C. Bhunia P. Sreedhar S.S. Mandal J. Shyam Sunder Reddy J.S. Yadav 《Tetrahedron letters》2007,48(46):8120-8124
Aryl propargylic methanols undergo C- and O-nucleophilic substitution reactions in the presence of a catalytic amount of iodine in short reaction times with good yields. 相似文献
26.
We analyse the Guionnet–Jones–Shlyakhtenko construction for the planar algebra associated to a finite-dimensional Kac algebra and identify the factors that arise as finite interpolated free group factors. 相似文献
27.
Spin dynamics under magic angle spinning has been studied using different theoretical approaches and also by extensive numerical simulation programs. In this article we present a general theoretical approach that leads to analytic forms for effective Hamiltonians for an N-spin dipolar and quadrupolar coupled system under magic angle spinning (MAS) conditions, using a combination of Floquet theory and van Vleck (contact) transformation. The analytic forms presented are shown to be useful for the study of MAS spin dynamics in solids with the help of a number of simulations in two, three, and four coupled, spin-1/2 systems as well as spins in which quadrupolar interactions are also present. 相似文献
28.
Sunder A Krämer M Hanselmann R Mülhaupt R Frey H 《Angewandte Chemie (International ed. in English)》1999,38(23):3552-3555
Polar dyes can be solubilized in apolar media-molecular nanocapsules with hydrophilic interiors have been prepared (see schematic representation) using polyglycerols with narrow polydispersity and simple esterification with fatty acids. These unimolecular micelles offer attractive potential for a variety of applications ranging from controlled drug release to the design of microreactors and catalysts. 相似文献
29.
Vijay?KodiyalamEmail author Zeph?Landau V.?S.?Sunder 《Proceedings Mathematical Sciences》2003,113(1):15-51
We obtain (two equivalent) presentations — in terms of generators and relations — of the planar algebra associated with the
subfactor corresponding to (an outer action on a factor by) a finite-dimensional Kac algebra. One of the relations shows that
the antipode of the Kac algebra agrees with the ‘rotation on 2-boxes’. 相似文献
30.
This paper is concerned with actions of finite hypergroups on sets. After introducing the definitions in the first section, we use the notion of maximal actions to characterise those hypergroups which arise from association schemes, introduce the natural sub-class of *-actions of a hypergroup and introduce a geometric condition for the existence of *-actions of a Hermitian hypergroup. Following an insightful suggestion of Eiichi Bannai we obtain an example of the surprising phenomenon of a 3-element hypergroup with infinitely many pairwise inequivalent irreducible *-actions. 相似文献