14686-14-7Relevant academic research and scientific papers
Chemistry and Kinetics of Dipropylcarbene in Solution
Tae, Eunju Lee,Zhu, Zhendong,Platz, Matthew S.,Pezacki, John Paul,Warkentin, John
, p. 5336 - 5342 (1999)
The photochemistry of 2-methoxy-2-methyl-5,5-dipropyl-Δ3-1,3,4-oxadiazoline (1a) and 2,2-dimethoxy-5,5-dipropyl-Δ3-1,3,4-oxadiazoline (1b) was investigated. Photolysis (300 nm) of these compounds in solution leads to fragmentation to 4-diazoheptane (major), which slowly forms the corresponding azine. Fragmentation to form 4-heptanone is also observed. Yields of 4-diazoheptane in CH2Cl2 are much larger than those in pentane. 4-Diazoheptane can be trapped with 1-pentene to form a pyrazoline or with methanol to form 4-methoxyheptane. The pyrazoline can be decomposed photochemically to form 1,1,2-tripropylcyclopropane. In solution, 4-diazoheptane is inefficiently photolyzed to dipropylcarbene (DPC), which can be trapped with piperidine or with pyridine in laser flash photolysis experiments. Analysis of the piperidine and pyridine data indicates that the lifetime of DPC in cyclohexane, methylene chloride, or Freon-113 (CF2ClCFCl2) solution at ambient temperature is controlled by 1,2 hydrogen migration to form Z- and E-3-heptene. The lifetime deduced under these conditions is ≈300 ps, which is about 20-fold shorter than that of dimethylcarbene in perfluorohexane at ambient temperature. Upon photolysis (254 nm) of oxadiazoline 1a in argon, 4-diazoheptane and 1-methoxydiazoethane are formed. These diazo compounds undergo subsequent photolysis that revealed the formation of methoxy(methyl)carbene and E- and Z-3-heptene. It was not possible to detect DPC in argon at 14 K.
Kolbe Electrolysis of Biomass-Derived Fatty Acids Over Pt Nanocrystals in an Electrochemical Cell
Yuan, Gang,Wu, Chan,Zeng, Guorong,Niu, Xiaopo,Shen, Guoqiang,Wang, Li,Zhang, Xiangwen,Luque, Rafael,Wang, Qingfa
, p. 642 - 648 (2019/12/24)
Electrochemical valorization of non-food biomass-derived carboxylates into fuels is promising for the conversion, storage, and distribution of renewable electricity. Herein, we demonstrate that biofuels, hydrogen, and bicarbonate can be simultaneously produced in an electrochemical cell by one-step electrolysis of free fatty acids under ambient conditions on 3D self-supported ultralow Pt loading (2 wt %) electrode. The three valuable products can naturally separate from each other during the electrolysis in the alkaline aqueous solution. The experimental suggests that Pt(100) and Pt(110) are favorable for the production of non-Kolbe and Kolbe hydrocarbons, respectively. DFT calculation further clarifies the adsorption and stabilization of the reaction intermediates on Pt(100) and Pt(110).
Designing bifunctional alkene isomerization catalysts using predictive modelling
Landman, Iris R.,Paulson, Erik R.,Rheingold, Arnold L.,Grotjahn, Douglas B.,Rothenberg, Gadi
, p. 4842 - 4851 (2017/10/23)
Controlling the isomerization of alkenes is important for the manufacturing of fuel additives, fine-chemicals and pharmaceuticals. But even if isomerization seems to be a simple unimolecular process, the factors that govern catalyst performance are far from clear. Here we present a set of models that describe selectivity and activity, enabling the rational design and synthesis of alkene isomerization catalysts. The models are based on simple molecular descriptors, with a low computational cost, and are tested and validated on a set of eleven known Ru-imidazol-phosphine complexes and two new ones. Despite their simplicity, these models show good predictive power, with R2 values of 0.60-0.85. Using a combination of principal components analysis (PCA) and partial least squares (PLS) regression, we construct a "catalyst map", that captures trends in reactivity and selectivity as a function of electrostatic charge on the N? atom, EHOMO, polar surface area and the optimal mass substituents on P/distance Ru-P ratio. In addition to indicating "good regions" in the catalyst space, these models also give insight into mechanistic steps. For example, we find that the electrostatic charge on N?, EHOMO and polar surface area are crucial in the rate-limiting step, whereas the optimal mass of substituents on P/distance Ru-P is correlated with the product selectivity.
General catalyst control of the monoisomerization of 1-alkenes to trans -2-alkenes
Larsen, Casey R.,Erdogan, Gulin,Grotjahn, Douglas B.
supporting information, p. 1226 - 1229 (2014/02/14)
After searching for the proper catalyst, the dual challenges of controlling the position of the double bond, and cis/trans-selectivity in isomerization of terminal alkenes to their 2-isomers are finally met in a general sense by mixtures of (C5Me5)Ru complexes 1 and 3 featuring a bifunctional phosphine. Typically, catalyst loadings of 1 mol % of 1 and 3 can be employed for the production of (E)-2-alkenes at 40-70 C. Catalyst comprising 1 and 3 avoids more than any other known example the thermodynamic equilibration of alkene isomers, as the trans-2-alkenes of both nonfunctionalized and functionalized alkenes are generated.
Graphite oxide activated zeolite NaY: Applications in alcohol dehydration
Todd, Alexander D.,Bielawski, Christopher W.
, p. 135 - 139 (2013/03/29)
A mixture of graphite oxide (GO) and the zeolite NaY (Si/Al = 5.1) was used to dehydrate various alcohols to their respective olefinic products. Using conditions optimized for 4-heptanol (15 wt% GO-NaY (1 : 1 wt/wt), 150°C, 30 min), a series of secondary and tertiary aliphatic alcohols were cleanly dehydrated in moderate to excellent conversions (27.5-97.2%). Several primary alcohols were also dehydrated, although higher catalyst loadings (200 wt% GO-NaY (1 : 1) and longer reaction times (3 h) were required. The enhanced dehydration activity was attributed to the ability of GO to convert NaY to an acidic form and without the need for ammonium cation exchange and/or high temperature calcination. The Royal Society of Chemistry 2013.
Pt/[Fe]ZSM-5 modified by Na and Cs cations: An active and selective catalyst for dehydrogenation of n-alkanes to n-alkenes
Li, Xuebing,Iglesia, Enrique
, p. 594 - 596 (2008/09/21)
Pt clusters within [Fe]ZSM-5 channels provide active and stable sites for the selective catalytic dehydrogenation of n-alkanes to n-alkenes. Cs and Na cations titrate acid sites and inhibit skeletal isomerization and cracking side reactions. The Royal Soc
Electrooptical liquid crystal system
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, (2008/06/13)
An electroptical system which between 2 electrode layers contains a PDLC film comprising a liquid crystal mixture forming micro-droplets in an optically isotropic, transparent polymer matrix, in which one of the refractive indices of the liquid crystal mixture is matched to the refractive index of the polymer matrix, which exhibits an electrically switchable transparency essentially independent of the polarization of the incident light, the precursor of the PDLC film of which comprises one or more monomers, oligomers and/or prepolymers and a photoinitiator, and is cured photoradically, the liquid crystal mixture of which comprises one or more compounds of the formula I in which the substituents are defined herein characterized in that the liquid crystal mixture additionally contains one or more reactive liquid crystalline compounds in order to obtain improved switching times especially at low temperatures.
Photolysis of dipropyldiazirine and trapping of dipropylcarbene with piperidine
Tae, Eunju Lee,Platz, Matthew S.
, p. 2875 - 2878 (2007/10/03)
Photolysis (350 nm) of dipropyldiazirine in methylene chloride at 4°C produces a mixture of E and Z 3-heptene in 81% yield in an E/Z ratio of 1.8. Tetrapropylazine was formed in less than 5% yield. Photolysis of dipropyldiazirine in the presence of piperidine leads to the formation of a carbene-amine adduct. In the presence of 0.06 M piperidine the yield of adduct is 48%, the yield of E and Z 3-heptene is 47% and the E/Z ratio of 3- heptenes is 1.1. The results show that heptene is formed by three pathways. One pathway involves dipropylcarbene formed directly from the diazirine, the other pathways are attributed to ionic and photochemical reactions of 4- diazoheptane and to the excited state of the diazirine precursor. Dipropylcarbene can be easily intercepted with a simple trap. The yield of this process is limited by the efficiency with which the precursor forms the carbene.
A convenient synthesis of episulfides and their conversion into alkenes
Dybowski, Piotr,Skowrońska, Aleksandra
, p. 1134 - 1136 (2007/10/03)
A convenient and stereoselective synthesis of episulfides based on the reaction of readily available S-(β-oxoalkyl) thiophosphate with sodium borohydride and their conversion into alkenes is described.
A NEW STRATEGY FOR THE STEREOSELECTIVE SYNTHESIS OF OLEFINS
Dybowski, Piotr,Skowronska, Aleksandra
, p. 4385 - 4388 (2007/10/02)
Highly stereoselective conversion of ketones into (Z)-olefins, via intermediate S-(β-oxoalkyl)thiophosphates and their seleno analogues is described.
