ChemInform Abstract: Bronsted Superacidity of HCl in a Liquid Chloroaluminate. AlCl3‐1‐Ethyl‐3‐methyl‐1H‐imidazolium Chloride (EMIC).

Smith, G. Pedro; Dworkin, A. S.; Pagni, Richard M.; Zingg, S. P.

doi:10.1002/chin.198918113

Cited by 8 publications

(18 citation statements)

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“…The conversion of THTCPD is promoted when a trace amount of H 2 O (0.5 wt %) is introduced, but the formation of C 15 H 24 is suppressed dramatically. The presence of trace water in chloroaluminate IL may generate some Brønsted acid, and the conjugation of Brønsted acid and Lewis acid produces superacid with the Hammett acidity of −18, noting that of CF 3 SO 3 H superacid is −14.1. − It is very possible that superacid species result in cracking of C 15 H 24 . Generally, many rearrangements have to be conducted in the solvent to enhance the formation and stabilization of carbonium.…”

Section: Resultsmentioning

confidence: 99%

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

et al. 2011

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As a work successive to AlCl 3 catalytic isomerization of tetrahydrotricyclopentadiene (THTCPD) [Wang, L.; Zhang, X.; Zou, J.-J.; Han, H.; Li, Y; Wang, L. Energy Fuels 2009, 23 (5), 2383À2388], the reaction using chloroaluminate ionic liquid (IL) was investigated. It is found that IL catalysis gives totally different product distribution. The endo-cycloproyl fragments of THTCPD that cannot be isomerized by AlCl 3 catalysis are transferred to exo conformation easily. Furthermore, the hydrocarbons are transferred to diamondoids, including methyl-1,2-tetramethyleneadamantane, methyl-diethyl-adamantane, and methyl-diamantane via skeletal rearrangement, with the first diamondoid as the primary and dominant product (selectivity > 80%). The IL shows much higher activity than superacid CF 3 SO 3 H, attributed to the synergetic effect of strong acidity and the novel solvent environment. Increasing the temperature, IL dosage, and AlCl 3 in IL can promote the rearrangement rate with a slight decrease in the selectivity of methyl-1,2-tetramethyleneadamantane. The presence of trace water in IL forms superacid and induces considerable cracking byproducts, and solvent typically used in rearrangement decreases the reaction rate. The diamondoid-based product shows a low freezing point and high hydrogen content and, thus, is superior as a high-energy-density fuel. This work may open a door for facile synthesis of diamondoid fuel. INTRODUCTIONThe rapid expansion of aeronautical and space technologies has been raising higher requirements for aerospace fuels, and a high volumetric energy content is specifically preferred for volumelimited aircrafts, such as missiles, rockets, and spacecrafts. 1À5 High-energy-density fuels provide much more propulsion energy than conventional distillated fuel and, thus, significantly increase the payload and flight range. They generally possess a compact cyclic structure to afford a high density and high energy content, such as tricyclic JP-10 (with a density of 0.94 g/mL and an energy content of 39.6 MJ/L) and pentacyclic RJ-5 (with a density of 1.08 g/mL and an energy content of 44.9 MJ/L). 1,5 Besides, the low-temperature performance of fuels, typically freezing point, is critical because they often encounter harsh environments, such as cold weather and high altitudes. JP-10 is the current standard missile fuel attributed to its low freezing point (À79°C), and RJ-5 is abolished because of its high freezing point (about 0°C).Diamondoids are hydrocarbons that have carbon framework superimposable on the diamond lattice, in which the adamantane cage is the basic unit. 6À8 Naturally occurring diamondoids are first discovered in some crude oil and natural gas condensates. Lower diamondoids, such as adamantane, diamantane, and triamantane, have been synthesized, but molecules containing more than four adamantane cages have not been prepared because of their complicated structure. 9À11 Owing to their compact structure, diamondoids has been regarded as a new kind of highenergy-density fuel, and the alkyl-su...

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Section: Resultsmentioning

confidence: 99%

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

et al. 2011

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“…Yang and Kou have determined the Lewis acidity of several chloroaluminate ionic liquids by means of a spectroscopic probe method. Recently, Smith et al, King et al, and Thomazeau et al described a procedure to evaluate the Brønsted superacidity of HCl in liquid chloroaluminate or the Brønsted acidity of HNTf 2 [NTf 2 = N(CF 3 SO 2 ) 2 ] in [BMIm][NTf 2 ] ionic liquid using the Hammett acidity function determined by UV−vis spectroscopy (Hammett method), wherein a basic indicator was used to trap the dissociative proton. Duan et al determined the acidity of several protic pyridinium ionic liquids by the Hammett method.…”

Section: Resultsmentioning

confidence: 99%

SO₃H-Functionalized Ionic Liquids for Selective Alkylation of p-Cresol with tert-Butanol

Liu

Zhou

Guo

et al. 2008

Ind. Eng. Chem. Res.

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The SO3H-functionalized ionic liquids were synthesized by using pyridine and 1,4-butane or 1,3-propane sulfone as the source and characterized by NMR and time-of-flight mass spectrometry. The acidity of the ionic liquids determined by the Hammett method is almost the same as that of a conventional acid, such as H2SO4. The catalytic performance of ionic liquids for the tert-butylation of p-cresol with tert-butanol was evaluated; by using the ionic liquids as catalysts at the optimum reaction conditions, 79% of the p-cresol conversion and 92% of the selectivity to 2-tert-butyl-p-cresol can be obtained. The spent ionic liquid can be recovered and recycled. The possible mechanism for this reaction system was discussed based on the reaction results and the ab initio calculation results.

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“…For improved control of the reaction process, the catalytic mechanism of chloroaluminate ionic liquid has been extensively reported [5][6][7][8][9][10]. Smith et al [11] found that arene was protonated by [Bmim]Cl-AlCl 3 /HCl, suggesting that the reaction was catalyzed by Bronsted superacidity obtained from the reaction: arene + Al 2 Cl 7  + HCl = arene-H + + 2[AlCl 4 ]  . Yoo et al [12] studied the alkylation of isobutane with 2-butene in [Bmim]Br-AlCl 3 , and proposed that alkylation is induced by a Bronsted acid [AlHCl 3 ] + which was formed by association of [Al 2 Cl 7 ]  with 2-H of imidazolium ring.…”

Section: Introductionmentioning

confidence: 99%

Alkylation mechanism of benzene with 1-dodecene catalyzed by Et3NHCl-AlCl3

et al. 2010

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ChemInform Abstract: Bronsted Superacidity of HCl in a Liquid Chloroaluminate. AlCl3‐1‐Ethyl‐3‐methyl‐1H‐imidazolium Chloride (EMIC).

Cited by 8 publications

References 1 publication

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

SO₃H-Functionalized Ionic Liquids for Selective Alkylation of p-Cresol with tert-Butanol

Alkylation mechanism of benzene with 1-dodecene catalyzed by Et3NHCl-AlCl3

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ChemInform Abstract: Bronsted Superacidity of HCl in a Liquid Chloroaluminate. AlCl3‐1‐Ethyl‐3‐methyl‐1H‐imidazolium Chloride (EMIC).

Cited by 8 publications

References 1 publication

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

Rearrangement of Tetrahydrotricyclopentadiene Using Acidic Ionic Liquid: Synthesis of Diamondoid Fuel

SO3H-Functionalized Ionic Liquids for Selective Alkylation of p-Cresol with tert-Butanol

Alkylation mechanism of benzene with 1-dodecene catalyzed by Et3NHCl-AlCl3

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SO₃H-Functionalized Ionic Liquids for Selective Alkylation of p-Cresol with tert-Butanol