- Electrochemical reactor for sustainable transformation of bio-mass derived allyl alcohol into acrylate and pure hydrogen
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Acrylic acid is widely used in the chemical, polymer, cosmetic and food industries. Typically, it is produced through processes with a high environmental impact. In this paper, we demonstrate the co-production of the potassium acrylate salt and hydrogen gas from allyl alcohol in a liquid flow fed anion exchange membrane electrolysis cell operating at 60 °C and ambient pressure. We compare in electrolysis cell tests, two electrocatalysts Pd/C and Pd-CeO2/C evaluating the activity and selectivity for acrylate production. Electrolysis cell parameters are tuned obtaining a maximum conversion of allyl alcohol of 96% and a selectivity to acrylate of 50% at an operating cell voltage of 1 V. Operating at a lower cell potential (0.7 V) the selectivity for acrylate increases to 74%. Hydrogen gas is produced in the separated cathode compartment at an energy cost of 26 KWh kgH2-1, which is around half when compared to state-of-the-art water electrolyzers. The electrochemical oxidation mechanism of allyl alcohol is also studied and discussed, providing for the first time an insight into the pathways for formation of acrylate with respect to the other principle oxidation products (propionate and 3-hydroxypropionate).
- Bellini, Marco,Di Vico, Benedetto,Innocenti, Massimo,Miller, Hamish Andrew,Oberhauser, Werner,Pagliaro, Maria Vincenza,Vizza, Francesco,Zangari, Giovanni
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- Cobalt-Catalyzed Acceptorless Dehydrogenation of Alcohols to Carboxylate Salts and Hydrogen
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The facile oxidation of alcohols to carboxylate salts and H2 is achieved using a simple and readily accessible cobalt pincer catalyst (NNNHtBuCoBr2). The reaction follows an acceptorless dehydrogenation pathway and displays good functional group tolerance. The amine-amide metal-ligand cooperation in cobalt catalyst is suggested to facilitate this transformation. The mechanistic studies indicate that in-situ-formed aldehydes react with a base through a Cannizzaro-type pathway, resulting in potassium hemiacetolate, which further undergoes catalytic dehydrogenation to provide the carboxylate salts and H2
- Gunanathan, Chidambaram,Kishore, Jugal,Pattanaik, Sandip,Pradhan, Deepak Ranjan
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supporting information
(2020/03/03)
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- PROCESS FOR MANUFACTURE OF CARBOXYLIC ACID SALTS
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The invention relates to a process for manufacture of carboxylic acid salts in the form of alkali metal or alkaline-earth metal carboxylates of 1 to 3 carbon atoms. The continuous manufacturing process comprises: 1) passing carboxylate salt of a starting cation through one or several ion exchange beds containing solid cation exchanger charged with an alkali metal or alkaline-earth metal cation,2) collecting a product solution containing alkali metal or alkaline-earth metal carboxylate eluted from the one or several ion exchange beds in step 1,3) simultaneously with step 1, regenerating one or several ion exchange beds containing solid cation exchanger charged with the starting cation by passing a regenerating solution containing a salt formed by an anion and the alkali metal or alkaline-earth metal cation through the one or several ion exchange beds,4) collecting an effluent solution containing the starting cation and the anion eluted from the one or several ion exchange beds in step 3, and 5) shifting the inlet and outlet points of the solutions in the same direction to other ion exchange beds._________________________________________________________
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- Bioreversible Protection for the Phospho Group: Bioactivation of the Di(4-acyloxybenzyl) and Mono(4-acyloxybenzyl) Phosphoesters of Methylphosphonate and Phosphonoacetate
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The di(4-acetoxybenzyl) ester of methylphosphonate 4 (X = H, R = Me) and the di(4-acyloxybenzyl) esters of methoxycarbonylmethylphosphonate 4 (X = MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) were prepared from the appropriate benzyl alcohol and phosphonic dichloride.At pD 8.0 and 37 deg C, both series of compounds hydrolyse with half-lives greater than 24 h to the corresponding mono(4-acyloxybenzyl) esters 5 (X = H or MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) which were prepared by treatment of the di(4-acyloxybenzyl) esters 4 with sodium or lithium iodide.The mono(4-acyloxybenzyl) esters 5 (X = H, R = Me) and 5 (X = MeO2C, R = Me, Et, Pr, iPr or tBu) undergo chemical hydrolysis to methylphosphonate 6 (X = H), and methoxycarbonylmethylphosphonate 6 (X = MeO2C), respectively, together with 4-hydroxybenzyl alcohol and the appropriate acylate anion.The rates of hydrolysis of the mono(4-acyloxybenzyl) esters decrease as the length and steric bulk of the acyl group increases, with half-lives ranging from ca. 150 h for the acetyl analogues to 2240 h for the pivaloyl derivative.The hydrolyses of the di- and mono-(4-acyloxybenzyl) esters were catalysed by porcine liver carboxyesterase (PLCE), and in all cases the acylate anion was formed.The rate of enzymatic hydrolysis was most rapid for the 4-butanoyloxybenzyl and 4-isobutanoyloxybenzyl analogues.The methoxycarbonyl ester of the phosphonoacetate analogues was not cleaved by PLCE.The methylphosphonate generated from the reaction of 4 (X = H, R = Me) in the presence of esterase and H2(18)O, did not contain (18)O attached directly to phosphorus.These results suggest that both the chemical and enzymatical hydrolyses of themono(4-acyloxybenzyl) esters and the PLCE-catalysed hydrolyses of the di(4-acyloxybenzyl) esters proceed via hydrolysis of the acyl group to give the acylate anion and the unstable 4-hydroxybenzyl esters.The electron-donating 4-hydroxy group facilitates the cleavage of the benzyl-oxygen bond with the formation of the 4-hydroxybenzyl carbonium ion 9, which readily reacts either with water or the phosphate buffer.The 4-acyloxybenzyl phosphoesters provide the first example of a protecting group which will enable the bioactivation of phosphonate prodrugs at rates appropriate to biological systems.
- Mitchell, Anthony G.,Thomson, William,Nicholls, Dave,Irwin, William J.,Freeman, Sally
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p. 2345 - 2354
(2007/10/02)
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- Relationship between the Electronic Structure of Acrylic and Methacrylic Acid and the Rates of Hydrogenation of Their Salts on Pt Black
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We have studied the hydrogenation of the alkali metal salt of acrylic and methacrylic acid on platinum black.The relative reactivities, which are interest in calculations of the electronic structure of acids, have been determined by the CNDO/2 method.
- Volkova, L. D.,Vyaznikovtseva, O. V.,Gabdrakipov, V. Z.,Sokol'skii, D. V.
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p. 1650 - 1652
(2007/10/02)
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