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A.B. (Middlebury College, 1959) M.A. (Wesleyan Univ., 1962) Ph.D. (Univ. of North Carolina, 1965) Research Associate (Cornell Univ., 1965-1966) Union Carbide Award for Chemical Education, Chemical Institute of Canada, 1982 McGill University Faculty of Science, Leo Yaffe Award for Excellence in Teaching (Inaugural Award), 1982 Chemical Manufacturer's Association National Catalyst Award (U.S., Canada), 1988 The Royal Society of Canada's McNeil Medal for the Public Awareness of Science (Inaugural Award), 1992 Beppo Award for the Popularization of Science, from the "Conseil de Developpement du loisir Scientifique du Quebec", 1993 The Edward Leete Award of the Organic Division of the American Chemical Society for Excellence in Teaching and Research (Inaugural Award), 1995 McGill University Graduate Faculty's David Thomson Award for Excellence in Graduate Supervision and Teaching, 1996 John A. Timm Award for Furtherance of the Study of Chemistry, New England Association of Chemistry Teachers, 1996 Michael Smith Award by the Government of Canada for the Promotion of Science, 1996 3 M Teaching Fellow, 1998 D.Sc. (honoris causa), Acadia University, Wolfville, N.S., 2000 Principal's Prize for Excellence in Teaching (Inaugural Award), Full Professor, 2001 James Flack Norris Award, N.E. Section of the ACS for excellence in teaching, 2003 Lifetime Achievement Award for Leadership in Learning, McGill University (Inaugural Award), 2010 LL.D., (honoris causa), University of Guleph, Guelph, Ontario, 201



Synthesis Part of our programme is to develop and perfect diatomic sulfur transfer reagent. These developments have further confirmed our earlier hypothesis[1] that there are likely to be a considerable number of reagents that will transfer 2 sulfur atoms. One of our new methods is the extremely practical and simple procedure of using elemental sulfur with a diene trapping reagent 1 in polar solvents (pyridine, DMSO).[2] This technique delivers trapped disulfur units (disulfide 2 and tetrasulfide 3) in variable ratios. Another method for disulfur transfer involves the sulfuration of dienes with a variety of organometallic polysulfides 4.[3] Here, 30-60% of sulfuration takes place. With 4b-d, ratios of disulfide to tetrasulfide trapping (3-5:1) are considerably higher than the ratios obtained (ca. 1.5:1) with the decomposition of alkoxydisulfides (ROSSOR) which we believe involves singlet diatomic sulfur (¹S2). These observation may be central to uncovering the nature of the well-known "activated sulfur" process referred to so frequently in the literature and often associated with the vulcanization process for rubber. A most unusual 2-sulfur addition reaction has been discovered.[4] Using thiosulfenyl chloride 5, this process inserts 2 sulfur atoms into dimethyldisulfide to give the tetrasulfide in 73% yield. Further, cyclic disulfides 2 are converted to tetrasulfides 3 in 82-90% yield. In an unprecedented reaction, 3 + 5 affords a cyclic hexasulfide in good yield (X-ray structure). The reaction is instantaneous at ca. -50°C. The process should function for tritylsulfenyl chloride 6 (a one atom sulfur addition) or bisthiosulfenyl choloride 7 (a three sulfur atom addition) permitting the immediate preparation of practically any symmetric polysulfide in a single, rapid step.[5] We intend to study the chemistry of the stable sulfur allotropes with our initial efforts concentrated on S10[6] and S12. Both can be prepared and stored with little difficulty. Initial experiments have shown that S10 decomposes to be captured by diene traps 1 in reasonable yield. The advantage here is that there is only the by-product of S8 in the inevitable problem of product purification. This is in significant contrast to the many other methods of generating S2. Further, we have found that S12 also decomposes to provide trapped products 2 and 3, however the ratio of 2:3 is reversed from that when S10 is used.[7] The implication here is that an S4 unit is preferentially transferred. We intend to perform mechanistic studies on this process; one idea is that the reaction is radical-based and evidence in that direction has already been obtained. A selection of some stable sulfur allotropes (including polymeric sulfur @ 7 o'clock) Finally, we hope to functionalize cubane with some of the standard sulfur functionalities such as thiols and disulfides. It would be interesting to see if the altered geometry at the 3° carbon would confer unusual properties on the attached sulfur. In spite of the hundreds of papers published on cubane structures, there is no example with a sulfur atom present and there are only two reports on cubyl alcohol with an indication that it is of limited stability.[8] Given some of the unusual properties of cubane derivatives, it is appropriate to investigate this novel situation. It appears that the cube shape seems capable of deactivating an enzyme responsible for Parkinson's disease[9] thus, it is rational to provide as many functionalities as possible for such investigations. To this end, cubane thiol, 8, the corresponding disulfide and related derivatives have been prepared. [10] Mechanism/Structure We plan to explore an unusual reaction recently discovered in our lab. When bis-alcohol 9 is treated with S2Cl2, three products are obtained (below). Our results indicate that we have obtained the dimer 10 (X-ray analysis), the monomer 11 and the thionosulfite 12. Dimer 10 delivers fascinating fluxional behaviour revealing two AB quartets in a 2:1 ratio (-80°C) reflecting two conformers of similar energy.[11] We plan to use calculations to model this system. We will examine the relationship of the two valence isomers 11 and 12. The corresponding sulfite has been independently prepared and characterized; it appears different from 11 in subtle ways. Here also, calculations have already indicated the close energy relationship between 11 and 12 (ca. 2 kcal/mol) but the energy barrier as well as the mechanism for conversion is not yet clear.[12] We will study alkoxydisulfides (ROSSOR) as to their structure, a topic debated for over 30 years.[13] The rotational barrier of these molecules is high (>18 kcal/mol) and we are exploring the fascinating possibility of separating disulfide enantiomers for the first time by a special chiral chromatographic column. The isomeric, "branch-bonded" thionosulfites such as 12 are known[14] in cyclic structures but the alkoxydisulfide isomer (ROSSOR) has been shown to be linear. Literature precedent exists for this remarkable behavior for the two known isomers of S2F2.[15] At present, we have been able to isolate and fully characterize (X-ray) both the alkoxydisulfide and thionosulfite thus supporting the idea that branch-bonded structures are required to explain the reactivity of a wide variety of molecules[16] including the easy acquisition of a sulfur atom by diallylsulfide from S8 by heating. A review article has been accepted on this topic[17].


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A. Z. Rys, E. K. V. Schultz and D. N. Harpp , 換uest for Diatomic Selenium?, J. Sulfur Chem ., 31 , 351-371 (2010). A. Z. Rys, I. A. Abu-Yousef and D. N. Harpp, 揂 Powerful Method to Prepare Sulfur-Rich Macrocycles?, Tetrahedron Lett ., 49 , 6670-6673 (2008). E. Zysman-Colman, P. Lesté-Lassere and D. N. Harpp, 揚robing the Chemistry of Rare Sulfur Allotropes: S 9 , S 12 and S 20 , J. Sulfur Chem ., 29 , 309-326 (2008). V. M. Carroll, D. N. Harpp and R. Priefer, 揟hermo-cage Opening of 4-iodo-1-vinylcubane to a Novel Styrene Derivative, Tetrahedron Lett ., 49 , 2677-2680, (2008) A. Z. Rys and D. N. Harpp, 揦anthane Hydride?, Electronic Encyclopaedia for Organic Reagents, John Wiley and Sons, 2007. A. Z. Rys and D. N. Harpp, ? 6,6-Dimethy.-1,4-Diseleno-3,7-Tetrasulfide, Electronic Encyclopaedia for Organic Reagents, John Wiley and Sons, 2007 R. Priefer, E. Martineau and D. N. Harpp , 揇erivitization of Dicubyl Disulfide, J. Sulfur Chem ., 28 , 529-535 (2007). E. Zysman-Colman and D. N. Harpp, 揊ascinating Organosulfur Functionalities. Polychalcogens as Diatomic Sulfur Sources?, Heterocycles , 18 , 449-459 (2007). I. A. Abu-Yousef, A. Z. Rys and D. N. Harpp , 揂 Novel Method for the Preparation of Unsymmetrical Bis (Di and Trisulfides) via Sulfenyl Chlorides ? Precursors for Cyclic Polysulfides?, J. Sulfur Chem. , 28 , 251-258 (2007). N. Eghbali and D. N. Harpp, 揑nvestigation of Sulfur Extrusion from a Cyclic Dialkoxy Disulfide?, J. Org. Chem. , 72 , 3906-3908 (2007). N. Eghbali, D. Scott Bohle and D. N. Harpp, ? Synthesis of New Cyclic Dialkoxy Disulfides?, J. Org. Chem. , 71 , 6659-6661 (2006). E. Zysman-Colman, N. Nevins, N. Eghbali, J. P. Snyder and D. N. Harpp, 揟he Crossover Point between Dialkoxy Disulfides and Thionosulfites ((RO 2 S=S): Prediction, Synthesis and Structure, J. Am. Chem. Soc ., 128 , 291-304 (2006). I. A. Abu-Yousef, A. Z. Rys and D. N. Harpp , "Preparation and Reactivity of Unsymmetrical Di- and Trisulfides?, J. Sulfur Chem. , 27 , 15-24 (2006). E. Zysman-Colman and D. N. Harpp, "Generalized Synthesis and Physical Properties of Dialkoxy Disulfides", J. Org. Chem., 70, 5964 (2005). A. Z. Rys, Y. Hou, I. A. Abu-Yousef and D. N. Harpp, "Diselenide-Assisted Sulfuration of Dienes", Tetrahedron Lett., 45, 9181, (2004). E. Zysman-Colman and D. N. Harpp, 揂 comparison of the structural properties of compounds containing the XSSX moiety (X = H, Me, R, Cl, Br, F, OR) ?, J. Sulfur Chem. , 25 , 291 (2004). E. Zysman-Colman and D. N. Harpp, 揂 comparison of the structural properties of compounds containing the XSSX moiety (X = H, Me, R, Cl, Br, F, OR) ?, J. Sulfur Chem. , 25 , 291 (2004). E. Zysman-Colman and D. N. Harpp, 揇ialkoxy Disulfides and Their Branch-Bonded Thionosulfite Isomers?, J. Sulfur Chem. , 25 , 155 (2004). E. Zysman-Colman, P. G. Farrell and D. N. Harpp , 揇esulfurization of Aromatic Polysulfides with Triphenylphosphine, J. Sulfur Chem. , 25 , 101 (2004). Balazy, I. A. Abu-Yousef, D. N. Harpp and J. Park, 揑dentification of Carbonyl Sulfide and Sulfur Dioxide in Porcine Coronary Artery by Gas Chromatography/Mass Spectrometry, Possible Relevance to EDHF?, Biochem. Biophys.Biophysical Res. Comm ., 311 , 728 (2003).