Dehydration of Benzyl Alcohols in Phosphonium Ionic Liquids: Synthesis of Ethers and Alkenes

Kalviri, Hassan A.; Kerton, Francesca M.

doi:10.1002/adsc.201100445

Cited by 21 publications

(12 citation statements)

References 51 publications

(46 reference statements)

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“…The decrease in yields is a result of byproduct formation such as dibenzylether [20]. Products and unreacted starting materials could be isolated from the reaction mixture via vacuum distillation, using apparatus described elsewhere [21]. Purified products could then be isolated via flash chromatography or fractional reduced pressure distillation.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous studies involving dehydration reactions of benzyl alcohols [20,21], equilibria between the alcohol and product were observed. In the studies herein varying quantities of dibenzyl ether co-product were noted.…”

Section: Mechanistic and Equilibrium Considerationsmentioning

confidence: 98%

“…The mixture was microwave-heated to 150 °C for 17 min whilst stirring. Upon cooling, the vial was transferred to a distillation apparatus and the chlorobutane isolated [21]. The ionic liquid phase was then treated as follows prior to re-use.…”

Section: General Procedures For Dehydroxyhalogenation Reactionsmentioning

confidence: 99%

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Halodehydroxylation of alcohols to yield benzylic and alkyl halides in ionic liquids

Petten

Kalviri

Kerton

2015

Sustain Chem Process

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Background: Alcohols are widely used, and sometimes renewable, reagents but the hydroxyl moiety is a relatively poor leaving group under mild conditions. Direct nucleophilic substitution of alcohols is a desirable reaction for synthetic and process chemists. Results: Synthesis of twelve alkyl and benzyl halides was achieved in [Bmim]PF 6 (Bmim = 1-butyl-3-methylimidazolium) from their parent alcohols using ammonium halides as the halogenating agents. Trends in reactivity based on the alcohol and halide were discovered. Mechanistic evidence suggests that the reaction proceeds via S N 2 substitution of the hydroxyl group, which is activated via hydrogen-bonding with the acidic proton of the imidazolium cation. Also, for benzyl substrates, equilibria involving formation of dibenzyl ether complicate the reactions and reduce optimum yields. Conclusions: Ammonium halides are useful, solid and relatively safe reagents for the conversion of some primary alcohols to organohalides in ionic liquids (yields up to 81 %). Indanol under the same conditions yields biindenylidene (GC yield 63 %).

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Section: Resultsmentioning

confidence: 99%

Section: Mechanistic and Equilibrium Considerationsmentioning

confidence: 98%

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Halodehydroxylation of alcohols to yield benzylic and alkyl halides in ionic liquids

Petten

Kalviri

Kerton

2015

Sustain Chem Process

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“…[32][33][34][35][36][37][38][39][40][41][42][43] In this way 1-phenyl ethanol, a by-product of the Oxirane process (propylene oxide synthesis), can be effectively utilized. Poisoning is a major problem for the most active heterogeneous systems, and research is ongoing to develop new liquid phase catalysts.…”

mentioning

confidence: 99%

“…Poisoning is a major problem for the most active heterogeneous systems, and research is ongoing to develop new liquid phase catalysts. [33][34][35][36][37][38][39][40][41][42][43] The serendipitous discovery of dehydration activity in toluene at low temperatures (100-120 °C) in the presence of acidic PEG gels, 44 led us to examine the dehydration activity and recycling of acidic ionic liquid gels, and compare this with the reaction catalyzed by the parent liquid and related SILP system. Appending a sulfonyl group to the cation of an ionic liquid or solid is achieved relatively easy by nucleophilic attack on a sultone.…”

mentioning

confidence: 99%

A Recyclable Acidic Ionic Liquid Gel Catalyst for Dehydration: Comparison with an Analogous SILP Catalyst

Wang

Ulrich

Donnelly

et al. 2015

ACS Sustainable Chem. Eng.

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An acid-functionalized ionic liquid was entrapped within a silica gel to yield a recyclable liquid phase catalyst for the dehydration of rac-1-phenyl ethanol. Hot filtration tests showed that the activity was within the gel. Comparison with an analogous SILP system revealed fundamental differences in the properties and behavior of the materials.The discovery of facile ionic-liquid silica gel formation, 1,2 enabled the introduction of the first ionic liquid mediated sol-gel methods for the preparation of solid catalysts. [3][4][5] There followed a period of relatively few publications, during which ionic liquid gels were seldom investigated as catalysts. Currently, in parallel with the development of new classes of ionic liquid, and an increase in interest in softmatter, the area of ionic liquid gel catalysts has come back into focus, and new methods are emerging. This catalyst preparation methodology involves the entrapment of an ionic liquid within an inorganic oxide matrix by a gel method. At the same time a catalyst is co-entrapped, 3,[5][6][7] or, alternatively the catalytic center can be associated with the ionic liquid. 4 The worked-up material is then used as a heterogeneous catalyst. Materials consisting of an ionic liquid within a porous oxide are often referred to as ionogels. 8 These catalysts are a sub-set of the sol-gel prepared entrapped catalysts pioneered by Blum and Avnir. 9,10 In contrast to the gel-based catalysts, the related SILP catalysts, in which a heterogeneous catalyst is prepared by layering an ionic liquid on a pre-existing oxide matrix, have elicited an explosion of interest in the last ten years. Several reviews and concept articles have been published covering the method. [11][12][13][14][15][16][17] Exemplars have been demonstrated in the gaseous phase, 18 and using supercritical fluids, [19][20][21] and the application of SILP technology is at an advanced stage. The simplicity of the system enables a wide variety of matrices, ionic liquids and dopants to be screened easily. In liquid phase reactions the ease of addition and removal of the ionic liquid is potentially detrimental, and leaching can be facile.The development of supported nanoparticles catalysts by ionic-liquid assisted gel methods 3 has been recently developed further by Han and co-workers. 22 Catalysts with hierarchical pores were achievable by employing a metal salt (e.g. CaCl 2 ) initiated gelation. Doping with gold afforded a catalyst for esterification, and ruthenium catalyzed hydrogenation.The introduction of functionalized ionic liquids that are 'task specific' 23-26 opens up many new possibilities for the application of ionic liquids to liquid phase reactions, not least the incorporation of Brønsted-Lowry Acidic/Basic sites. Acid functionalized ionic liquids have been demonstrated as robust catalysts for continuous esterification in a miniplant. 27 In order to improve separation and prevent corrosion caused by liquid phase acids, it would be fortuitous to develop a heterogenised system. The combinat...

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Selective Oxidation of Alcohols to Carbonyls Under Decatungstate‐Mediated Photoelectrochemical Conditions

Capucciati,

Baraglia,

Cassera

et al. 2024

Chemistry A European J

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The oxidation of alcohols to the corresponding carbonyl derivatives has been realized under photoelectrochemical conditions in the presence of tetrabutylammonium decatungstate (TBADT) as the homogeneous photocatalyst. The protocol can be applied to both primary and secondary, benzylic and aliphatic alcohols. The desired products are obtained selectively, skipping the need for purposely added chemical oxidants. An in‐depth study of photoelectrochemical conditions revealed that the protocol works best under amperostatic conditions in an undivided electrochemical cell irradiated with a 390 nm LED lamp. The comparison with analogous electrochemical and chemical oxidant‐promoted photocatalytic oxidations demonstrates the superior efficiency and selectivity of the hereby reported photoelectrochemical conditions.

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Dehydration of Benzyl Alcohols in Phosphonium Ionic Liquids: Synthesis of Ethers and Alkenes

Cited by 21 publications

References 51 publications

Halodehydroxylation of alcohols to yield benzylic and alkyl halides in ionic liquids

Halodehydroxylation of alcohols to yield benzylic and alkyl halides in ionic liquids

A Recyclable Acidic Ionic Liquid Gel Catalyst for Dehydration: Comparison with an Analogous SILP Catalyst

Selective Oxidation of Alcohols to Carbonyls Under Decatungstate‐Mediated Photoelectrochemical Conditions

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