Ionic dimerisation of methyl trifluoropropenoate

1980 ◽  
Vol 45 (2) ◽  
pp. 415-422 ◽  
Author(s):  
Oldřich Paleta ◽  
Václav Havlů ◽  
Václav Dědek
Keyword(s):  
Proton Transfer ◽  
Potassium Fluoride ◽  
Complete Conversion ◽  
Reaction Conditions ◽  
Kinetically Controlled

Dimerisation of methyl trifluoropropenoate (I) in solvents in the presence of potassium fluoride affords stereoisomeric dimethyl perfluoro-(4-methyl-2-pentene)dioates (III), the ratio of which depends on the reaction conditions. The reaction is accompanied by formation of methyl 2,3,3,3-tetrafluoropropenoate (IV), arising by proton transfer from the solvent to the carbanionic intermediate. Under suitable conditions complete conversion of the propenoate can be achieved and the dimer is obtained in 80-90% yield. Principal steps of the dimerisation were proved and the formation of configurational isomers is discussed in terms of kinetically controlled reaction.

Anionic cis-trans isomerisation of dimethyl perfluoro-(4-methyl-2-pentene)dioate

1980 ◽  
Vol 45 (12) ◽  
pp. 3360-3369 ◽  
Author(s):  
Oldřich Paleta ◽  
Jiří Svoboda ◽  
Václav Havlů ◽  
Václav Dědek
Keyword(s):  
Proton Transfer ◽  
Title Compound ◽  
Heterogeneous System ◽  
Equilibrium Mixture ◽  
Potassium Fluoride ◽  
Side Product ◽  
Solvation Effect ◽  
Aprotic Solvents ◽  
Reaction Conditions ◽  
Dipolar Aprotic Solvents

Potassium fluoride induced cis-trans isomerisation of the title compound I was investigated. The isomerisation takes place in a heterogeneous system and is enabled by solvation effect of dipolar aprotic solvents. Dimethyl 2,3,3,4-tetrafluoro-2-trifluoromethylpentanedioate (II) is formed as side product by proton transfer from the solvent to the intermediate 1,3-bis(methoxycarbonyl)perfluoro-1-butanide (III). The mechanism was deduced from the reaction conditions and results of the isomerisation. Composition of the equilibrium mixture of cis- and trans-isomer (Ia, Ib, respectively) studied in the interval 2-75 °C, shows an extreme. In the interval 2-30 °C the reaction Ia → Ib appears to be exothermic (ΔH = -21.2 kJ mol-1), in the interval 35-47 °C the enthalpy equals practically zero and in the maximum of the curve at 42.5 °C the entropic factor ΔS = 2.82 J mol-1 K-1. In the interval 50-75 °C the reaction is endothermic (ΔH = 15.2 kJ mol-1). In this context the effect of steric interactions between the substituents -COOCH3 and -CF(CF3)COOCH3, as well as of the so called cis-effect in 1,2-dihalogenoethylenes, on the Ia ##e Ib equilibrium are discussed.

Ionic dimerisation of trifluoropropenenitrile and its addition reactions with methyl trifluoropropenoate

1980 ◽  
Vol 45 (2) ◽  
pp. 406-414 ◽  
Author(s):  
Jiří Svoboda ◽  
Oldřich Paleta ◽  
Václav Dědek
Keyword(s):  
Reaction Mechanism ◽  
Proton Transfer ◽  
Substituent Effect ◽  
Solvent Molecule ◽  
Addition Product ◽  
Potassium Fluoride ◽  
Relative Reactivity ◽  
Addition Reactions ◽  
Tertiary Amines ◽  
Optimum Conditions

Dimerisation of trifluoropropenenitrile (I) in the presence of potassium fluoride and tertiary amines afforded a mixture of stereoisomeric perfluoro-4-methyl-pentenedinitriles (II), higher-boiling compounds, and 2,3,3,3-tetrafluoropropanenitrile (III) which arises by proton transfer from the solvent molecule. Under optimum conditions, product II was obtained in about 50% yield. Reaction of the nitrile I with methyl trifluoropropenoate (IV) gave, besides the dimers II and V, the product of addition of the nitrile I to the propenoate, IV, i.e. methyl 4-cyanoperfluoro-2-pentenoate (VI), and the addition product of the propenoate IV to the nitrile I, i.e. methyl 4-cyanoperfluoro-2-methyl-3-butenoate (VII). The relative reactivity if I and IV is discussed. The ratio of stereoisomers in II, V, VI and VII indicates that the magnitude of the steric substituent effect, operating in the reaction mechanism, decreases in the order -CFCF3.(COOCH3) > -CFCF3(CN) > -COOCH3 > -CN.

Intensification of the Production of 2-Ethyl-Hexyl Acrylate: Batch Kinetics and Reactive Distillation

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Vivek D. Talnikar ◽  
Onkar A. Deorukhkar ◽  
Amit Katariya ◽  
Yogesh S. Mahajan
Keyword(s):  
Kinetic Model ◽  
Acrylic Acid ◽  
Process Development ◽  
Reactive Distillation ◽  
Batch Reactor ◽  
Process Intensification ◽  
Complete Conversion ◽  
Reaction Conditions ◽  
Batch Mode ◽  
Batch Kinetics

Abstract The reaction of acrylic acid and 2-ethyl-1 hexanol was explored in this work with the intent of process intensification. In order to assess the effect of important parameters on the course of reaction, this work initially conducted batch reactor experiments. Reaction conditions in the batch reactor for a specific conversion (~ 30 %) were obtained. A kinetic model was then obtained through regression to arrive at a rate expression that is later used in process development. Experiments were performed in the reactive distillation (RD) environment in batch mode, which showed substantial increase in conversion (~ 80 %) indicating the applicability of RD. Further, this work performed simulation in the RD environment to assess process intensification. Simulations show that it is possible to obtain complete conversion of the acid.

scholarly journals Highly selective synthesis of citronellal in water at multigram scale by Pd nanoparticles-catalyzed hydrogenation of citral

2021 ◽  
Author(s):  
DUVAL Marion ◽  
SAGORIN Gilles ◽  
Audrey Denicourt-Nowicki ◽  
Alain ROUCOUX
Keyword(s):  
Double Bond ◽  
Palladium Nanoparticles ◽  
Potassium Hydroxide ◽  
Pd Nanoparticles ◽  
Added Value ◽  
Selective Synthesis ◽  
Complete Conversion ◽  
Turnover Number ◽  
Reaction Conditions ◽  
Excellent Selectivity

The synthesis of citronellal, an added-value chemical for perfumery, was carried out by selective and green hydrogenation of citral into citronellal in water. Aqueous suspensions of spherical ammonium-capped palladium nanoparticles with sizes around 3nm selectively reduced the conjugated carbon-carbon double bond. An excellent selectivity of 95% in citronellal was achieved at complete conversion under mild reaction conditions on a realistic 2 g scale in water. The presence of potassium hydroxide proved crucial to control the selectivity and avoid other hydrogenation co-products. These optimized results were further extended to a 135 g substrate loading with a relevant turnover number (TON) of 10 000.

Organocatalytic Trapping of Elusive Carbon Dioxide based Heterocycles through a Kinetically Controlled Cascade Process

2020 ◽  
Author(s):  
Chang Qiao ◽  
Alba Villar-Yanez ◽  
Josefine Sprachmann ◽  
Bart Limburg ◽  
Carles Bo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Computational Analysis ◽  
Cascade Process ◽  
Cyclic Carbonates ◽  
Reaction Conditions ◽  
Heterocyclic Base ◽  
Alcohol Group ◽  
Kinetically Controlled ◽  
Novel Approach

<div>A conceptually novel approach is described for the</div><div>synthesis of larger-ring cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a beta-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an N-heterocyclic base allows for equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be conveniently trapped by an acylation agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of novel six-membered cyclic carbonates in excellent yields and chemoselectivities under remarkably mild reaction conditions. This newly developed protocol helps to expand the repertoire of CO2-based heterocycles that are otherwise difficult to generate by conventional approaches.</div>

scholarly journals Organocatalytic Trapping of Elusive Carbon Dioxide based Heterocycles through a Kinetically Controlled Cascade Process

2020 ◽  
Author(s):  
Chang Qiao ◽  
Alba Villar-Yanez ◽  
Josefine Sprachmann ◽  
Bart Limburg ◽  
Carles Bo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Computational Analysis ◽  
Cascade Process ◽  
Cyclic Carbonates ◽  
Reaction Conditions ◽  
Heterocyclic Base ◽  
Alcohol Group ◽  
Kinetically Controlled ◽  
Novel Approach

<div>A conceptually novel approach is described for the</div><div>synthesis of larger-ring cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a beta-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an N-heterocyclic base allows for equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be conveniently trapped by an acylation agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of novel six-membered cyclic carbonates in excellent yields and chemoselectivities under remarkably mild reaction conditions. This newly developed protocol helps to expand the repertoire of CO2-based heterocycles that are otherwise difficult to generate by conventional approaches.</div>

scholarly journals CuO-Fe2O3 Nanoparticles Supported on SiO2 and Al2O3 for Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 625
Author(s):  
Anastasiya A. Shesterkina ◽  
Anna A. Strekalova ◽  
Elena V. Shuvalova ◽  
Gennady I. Kapustin ◽  
Olga P. Tkachenko ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
High Selectivity ◽  
Particle Distribution ◽  
Oxide Phase ◽  
Metal Particles ◽  
Complete Conversion ◽  
Reaction Conditions ◽  
Ftir Studies ◽  
Fe Catalysts ◽  
Average Size

In this study, novel SiO2- and Al2O3-supported Cu-Fe catalysts are developed for selective hydrogenation of 2-methyl-3-butyne-2-ol to 2-methyl-3-butene-2-ol under mild reaction conditions. TEM, XRD, and FTIR studies of adsorbed CO and TPR-H2 are performed to characterize the morphology, nanoparticle size, and particle distribution, as well as electronic state of deposited metals in the prepared catalysts. The deposition of Fe and Cu metal particles on the aluminum oxide carrier results in the formation of a mixed oxide phase with a strong interaction between the Fe and Cu precursors during the calcination. The highly dispersed nanoparticles of Fe2O3 and partially reduced CuOx, with an average size of 3.5 nm and with strong contact interactions between the metals in 5Cu-5Fe/Al2O3 catalysts, provide a high selectivity of 93% toward 2-methyl-3-butene-2-ol at complete conversion of the unsaturated alcohol.

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