463-82-1Relevant articles and documents
Molecular insight into surface organometallic chemistry through the combined use of 2D HETCOR solid-state NMR spectroscopy and silsesquioxane analogues
Chabanas,Quadrelli,Fenet,Coperet,Thivolle-Cazat,Basset,Lesage,Emsley
, p. 4493 - 4496 (2001)
Feher cage analogues, such as 1, provide easy access to models of surface structures such as 2, and give a better understanding of surface reactions. In addition, surface complexes such as 2 can be fully characterized by high-resolution 1D and 2D solid-state NMR spectroscopy.
The effect of the dynamics of revolving gates on the kinetics of molecular encapsulation-The activity/selectivity relationship
Rieth, Stephen,Badjic, Jovica D.
, p. 2562 - 2565 (2011)
Gated molecular encapsulation: The relationship between the rate by which guest molecules enter/exit gated hosts and the rate by which gates revolve and thereby open/close the host were investigated. The results of kinetic measurements have indicated that more dynamic hosts are also more selective in trapping guests, thereby revealing an activity/selectivity relationship pertaining molecular recognition events (see figure).
Gated molecular recognition and dynamic discrimination of guests
Rieth, Stephen,Bao, Xiaoguang,Wang, Bao-Yu,Hadad, Christopher M.,Badjic, Jovica D.
, p. 773 - 776 (2010)
Some highly efficient enzymes, e.g., acetylcholinesterase, use gating as a tool for controlling the rate by which substrates access their active site to direct product formation. Mastering gated molecular encapsulation could therefore be important for manipulating reactivity in artificial environments, albeit quantitative relationships that describe these processes are unknown. In this work, we examined the interdependence between the thermodynamics (ΔG° ) and the kinetics (ΔGin? and ΔGout?) of encapsulation as mediated by gated molecular basket 1. For a series of isosteric guests (2-6, 106-107 A3) entering/ exiting 1, we found a linear correlation between the host-guest affinities (ΔG° ) and the free energies of the activation (ΔG in? and ΔGout?), which was fit to the following equation: ΔG? = ρΔG° + δ. Markedly, the kinetics for the entrapment of smaller guest 7 (93 A3) and bigger guest 8 (121 A3) did not follow the free energy trends observed for 2-6. Thus, it appears that the kinetics of the gated encapsulation mediated by 1 is a function of the encapsulation's favorability (ΔG° ) and the guest's profile. When the size/shape of guests is kept constant, a linear dependence between the encapsulation potential (ΔG° ) and the rate of guests' entering/departing basket (ΔGin/out?) holds. However, when the potential (ΔG° ) is fixed, the basket discriminates guests on the basis of their size/shape via dynamic modulation of the binding site's access.
Thermochemistry of conjugation of simple cyclopropane derivatives
Fuchs, Richard,Hallman, John H.,Perlman, Michael O.
, p. 1832 - 1835 (1982)
Heats of vaporization of cyclopropyl cyanide and cyclopropylbenzene have been measured by vaporization calorimetry, and combined with liquid state heats of formation to give gaseous state heats of formation.When these compounds, cyclopropane, 1,1-dimethylcyclopropane, and cyclopropylamine are involved in (hypothetical) isodesmic reactions with ethane to give the isopropyl derivative and propane, the enthalpies of reaction are -116.0 +/- 1.3 kJ mol-1, except for cyclopropylbenzene (-103.7 kJ mol-1).The latter is less exothermic, in part, because of slight steric destabilization of the product, isopropylbenzene, but mainly due to 8 kJ mol-1 stabilization of cyclopropylbenzene, which is the only of these cyclopropyl derivatives showing appreciable thermochemical stabilization.
Extension of surface organometallic chemistry to metal?organic frameworks: Development of a well-defined single site [(≡Zr? O?)W(=O)(CH2TBu)3] olefin metathesis catalyst
Thiam, Zeynabou,Abou-Hamad, Edy,Dereli, Busra,Liu, Lingmei,Emwas, Abdul-Hamid,Ahmad, Rafia,Jiang, Hao,Isah, Abdulrahman Adamu,Ndiaye, Papa Birame,Taoufik, Mostafa,Han, Yu,Cavallo, Luigi,Basset, Jean-Marie,Eddaoudi, Mohamed
supporting information, p. 16690 - 16703 (2020/11/09)
We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT?IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.
PRODUCTION OF NEOPENTANE
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Paragraph 0048-0054, (2018/03/25)
Disclosed herein are processes for producing neopentane. The processes generally relate to demethylating neohexane and/or neoheptane to produce neopentane. The neohexane and/or neoheptane may be provided by the isomerization of C6-C7 paraffins.
Formation of an alkyne during degradation of metal-alkylidyne complexes
Levy, Ophir,Musa, Sanaa,Bino, Avi
, p. 12248 - 12251 (2013/09/02)
The compound [(Ot-Bu)3WCt-Bu] (1) (t-Bu = C(CH3) 3) decomposes upon contact with water and several organic products are formed, including di-tert-butylacetylene, t-BuCCt-Bu. This process is reminiscent of the degradation of trinuclear metal-alkylidyne complexes in which free carbynes are ejected into solution, couple and form alkynes along with many other products. The reactivity pattern of the resulting t-BuC carbynes that includes extensive hydrogen abstraction, cleavage of alkynes and lack of reactivity towards alkenes is indicative of a quartet (S = 3/2) spin state. A similar spin state was assigned to other RC (R = alkyl) species that were produced by degrading M3-alkylidyne (M = transition metal) complexes in water. t-BuCCt-Bu is also produced during thermal decomposition of solid 1. In 1977 Fischer and co-workers reported a very similar process in which solids of Br(CO)4CrCR1 and Br(CO)4CrCR2 were co-thermolyzed to produce R1CCR2, R 1CCR1, and R2CCR2. Fischer had considered the involvement of free carbynes in the making of the alkynes but later resorted to other explanations. The current results suggest that his original proposal is indeed valid.
Tandem cyclopropanation with dibromomethane under Grignard conditions
Brunner, Gerhard,Eberhard, Laura,Oetiker, Juerg,Schroeder, Fridtjof
, p. 7543 - 7554 (2008/12/22)
(Chemical Equation Presented) Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnesium and CH 2Br2 under Barbier conditions at higher temperatures. The reaction rates depend on the substitution pattern of the (homo)allylic alcoholates and on the counterion with lithium giving best results. Good to excellent syn-selectivities are obtained from α-substituted substrates, which are in accord with a staggered Houk model. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropyl carbinols.
Alkane metathesis catalyzed by a well-defined silica-supported Mo imido alkylidene complex: [(≡SiO)Mo(=NAr)(=CHtBu)(CH2tBu)]
Blanc, Frederic,Coperet, Christophe,Thivolle-Cazat, Jean,Basset, Jean-Marie
, p. 6201 - 6203 (2007/10/03)
A two-functions-in-one catalyst precursor allows an olefin metathesis catalyst to be turned into an alkane metathesis catalyst. A silica-supported alkyl alkylidene molybdenum complex containing an ancillary imido ligand is a highly active olefin metathesis catalyst and also acts as a catalyst precursor for alkane metathesis. This system involves a single metal with dual properties and shows that ancillary ligands are compatible with alkane metathesis reactions. (Chemical Equation Presented).
Supported ionic liquid and the use thereof in the disproportionation of isopentane
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Page/Page column 1-2, (2008/06/13)
A catalyst system containing an ionic liquid dispersed on a support having an average pore diameter greater than about 225 ? is disclosed. The catalyst system is employed in a process to disproportionate a C5 paraffin.
