Unreacted Alcohol Research Articles

The assessment of sustainability indicators for triglycerides transesterification with alcohols catalyzed by ion exchange resins

The research was aimed at determining the dependences of sustainability indicators on the parameters of the sunflower oil transesterification with ethyl, propyl, and butyl alcohol catalyzed by anion exchange resin AV-17-8 with OH– ions or cation exchange resin KU-2-8 with H+ or immobilized Zn2+, Sn2+, Ni2+, Co2+, and Cu2+ ions. Such sustainability indicators as the E-factor, atomic efficiency, mass intensity and mass productivity, reaction mass efficiency, stoichiometric factor, etc., have been determined. We established that sustainability indicators of transesterification catalyzed by ion exchange resins depend on the yield of higher fatty acid esters that can be achieved by immobilized metal ions. The unreacted alcohol regeneration significantly reduces the E-factor value and increases the reaction mass efficiency. During the sunflower oil ethanolysis, the minimum E-factor value is achieved at the ethyl alcohol:triglyceride molar ratio corresponding to the maximum yield of higher fatty acid esters. The reaction mass efficiency calculated without considering the unreacted alcohol regeneration is one of the criteria for determining its regeneration expediency. The sustainability indicators are the additional criteria for selecting optimal conditions of the sunflower oil transesterification with aliphatic alcohols catalyzed by ion exchange resins. The calculated sustainability indicators indicate that the investigated ion exchange resins as heterogeneous transesterification catalysts provide a high yield of higher fatty acid esters. Using the researched catalysts ensures a low E-factor, making the process environmentally friendly.

A New Approach to Prepare Chiral Aroma: Asymmetric Oxidation of Ionols with a Heme Acquisition System A Derived from Symbiotic Fluorescent Bacteria.

The aim of this study was to propose an alternative route for preparing chiral β- and α-ionols by asymmetric oxidation with a heme acquisition system A (HasA) derived from symbiotic fluorescent bacteria as a biocatalyst. The HasA (6 g) in distilled water (300 mL) was stirred at 1150 rpm for 1 day at 40°C. Subsequently, a secondary alcohol (0.77 mmol) as a substrate in 2% 2-propanol was added to the catalyst solution. After verifying that the oxidation proceeded to ca 50% using gas chromatography (GC), the reaction mixture was filtered, extracted, washed, and dried over. The extract was concentrated in vacuo and purified using silica gel column chromatography to yield the oxidized product and recover the unreacted alcohol. β-Ionol was oxidized into β-ionone in a conversion of ca. 50% in the presence of the HasA for three days, and the remaining alcohol was recovered and analyzed using chiral GC after acetylation. The HasA selectively catalyzed the asymmetric oxidation of β-ionol with a preference for the (R)- form to recover (S)-β-ionol with 96.4 ±1.6% enantiomeric excess (ee). In addition, α-ionol was similarly oxidized into α-ionone in a conversion of ca. 50% for seven days, preferentially remaining (9S)-α-ionol with 97.9 ± 0.2% ee. The characteristic aroma of (S)-β-ionol obtained by the asymmetric oxidation with the HasA showed floral and fruity like, while the aroma of (9S)-α-ionol described as violet and sweet. In this study, we successfully developed a new approach to prepare enantiomerically pure (S)-β- and α-ionols by the asymmetric oxidation with the HasA.

Unlocking the Friedel-Crafts arylation of primary aliphatic alcohols and epoxides driven by hexafluoroisopropanol

Unlocking the Friedel-Crafts arylation of primary aliphatic alcohols and epoxides driven by hexafluoroisopropanol

Lipase immobilized graphene oxide biocatalyst assisted enzymatic transesterification of Pongamia pinnata (Karanja) oil and downstream enrichment of biodiesel by solar-driven direct contact membrane distillation followed by ultrafiltration

The present experimental investigation has shown the biodiesel production from 2nd generation renewable carbon source, Karanja seed oil using graphene oxide (GO) immobilized lipase biocatalyst. The adsorption of lipase in GO was found to be most suitable immobilizing support matrix (adsorbed ~94 mg/g of GO) due to large specific surface area and abundant functional groups. The GO immobilized enzyme i.e. biocatalysts assisted enzymatic transesterification yielded ~88% of biodiesel using 1:8 Karanja oil: ethanol ratio, 25 °C, 3% biocatalysts in 24 h reaction time. The newly designed solar-driven direct contact membrane distillation module enables continuous separation and recycles of unreacted alcohol (>99% recovery) from transesterification reaction mixture while yielding ~41 Kg EtOH/m2/24h using commercial PTFE/PET hydrophobic membrane. Subsequently, free glycerol was removed up to ~77% (permeate concentration ≤0.018 mass%) by cross-flow membrane module fitted with flat-sheet polyethersulfone ultrafiltration membrane. The integration of GO-based biocatalyst assisted transesterification and multi-staged membrane system for downstream enrichment of fatty acid ethyl ester culminates in the development of a cost-effective, energy-intensive and eco-friendly system which represents a sustainable biofuel production process.

Sustainable Method for the Synthesis of Alternative Bis(2-Ethylhexyl) Terephthalate Plasticizer in the Presence of Protic Ionic Liquids

Inexpensive Brønsted acidic ionic liquids based on trimethylamine and sulfuric acid are proposed as both solvents and catalysts in the synthesis of alternative plasticizer bis(2-ethylhexyl) terephthalate, which has a broad spectrum of applications in plasticization processes. The utilization of 50 mol % of Brønsted ionic liquid led to the full conversion of terephthalic acid after 8 h of reaction at 120 °C. Additionally, a 100% selectivity of bis(2-ethylhexyl) terephthalate was obtained. The advantage of the presented reaction system is based on the formation of a biphasic system during the reaction. The bottom phase consists of an ionic liquid and water, and the upper phase is created by the ester and unreacted alcohol. This phenomenon helps overcome the equilibrium of the reaction and drives it towards a high yield of product. The presented new approach is proposed as a safe, cost-effective, and alternative method to conventional processes with organometallic compounds that, in turn, leads to greener and a more economically viable technology.

Photoinduced Proton-Transfer Reactions for Mild O-H Functionalization of Unreactive Alcohols.

Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. Mechanistic studies indicate there is a preorganization of hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen‐bonding complex. Only after photoexcitation does this complex undergo a protonation‐substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O‐H functionalization reactions (54 examples, up to 98 % yield).

Scalable and Phosphine-Free Conversion of Alcohols to Carbon-Heteroatom Bonds through the Blue Light-Promoted Iodination Reaction.

One of the fundamental and highly valuable transformations in organic chemistry is the nucleophilic substitution of alcohols. Traditionally, these reactions require strategies that employ stoichiometric hazardous reagents and are associated with difficulty in purification of the by-products. To overcome these challenges, here, we report a simple route toward the diverse conversion of alcohols via an SN2 pathway, in which blue light-promoted iodination is used to form alkyl iodide intermediates from simple unreactive alcohols. The scope of the process tolerates a range of nucleophiles to construct C-N, C-O, C-S, and C-C bonds. Furthermore, we also demonstrate that this method can be used for the preparation and late-stage functionalization of pharmaceuticals, as highlighted by the syntheses of thiocarlide, butoxycaine, and pramoxine.

Tetrasubstituted allenes via the palladium-catalysed kinetic resolution of propargylic alcohols using a supporting ligand

Efficient enantioselective construction of fully substituted allenes from simple starting materials is still a fundamental challenge due to the difficulty to discriminate between the four substituents at the 1- and 3-positions of the three-carbon axis of chirality. Here, we report a straightforward catalytic asymmetric synthesis of tetrasubstituted 2,3-allenoic acids from readily available racemic propargylic alcohols. Enabled by the co-catalysis of palladium and a Bronsted acid in the presence of a commercially available chiral ligand (DTBM-SEGphos) and an achiral monophosphine supporting ligand (PPh3), the kinetic resolution of propargylic alcohols proceeded efficiently in the presence of water and 1 atm CO, affording tetrasubstituted 2,3-allenoic acids in excellent enantioselectivity and atom economy with a good functional group compatibility. Performing a second kinetic resolution on the unreacted alcohol gave access to the other enantiomer of the product. These allenes are precursors to compounds with quaternary carbon centres and other chiral tetrasubstituted allene building blocks, which are of great interest. Asymmetric routes for the formation of tetrasubstituted allenes are scarce and limited in scope. Now, a catalytic asymmetric process is reported giving access to tetrasubstituted allenes from readily available propargylic alcohols, and a potential role for an achiral supporting ligand is postulated.

Metal hydrated-salts as efficient and reusable catalysts for pre-treating waste cooking oils and animal fats for an effective production of biodiesel

A very efficient chemical pre-treatment method that uses cheap and safe hydrated-salts as catalysts for the conversion of waste cooking oils and animal fats having a high Free Fatty Acids (FFAs) content into an oily feedstock convertible into biodiesel through a conventional route (basic catalysis) was investigated. These hydrated-salts allow FFAs to be efficiently (>99%) esterified with alcohols under very mild conditions (343 K, 2 h). At the end of this treatment, a very convenient separation of products was verified. Two different phases were eventually obtained: an upper alcoholic phase, which contains most of the unreacted alcohol, water obtained by direct-esterification (>95%), and the salt that was used as catalyst (recovery >99%); and a lower oily-phase mainly composed of glycerides, methyl-esters derived from direct-esterification of FFAs (residual acidity of about 0.8 mg KOH/g), and part of unreacted alcohol (7–10%wt). Such a separation was convenient because the oily-phase could be directly trans-esterified through conventional base-catalysis, without any further pre-treatments, thus avoiding production of salty-waste. Also, the alcoholic phase could be recovered and directly re-used for new pre-treatments cycles of fresh waste-oils. A final scheme of the proposed process was discussed and the relevant advantages with respect to conventional routes were highlighted.

Liquid–liquid equilibria of systems containing linseed oil biodiesel + methanol + glycerol: Experimental data and thermodynamic modeling

Biodiesel is known as a prominent candidate for the replacement of fossil-based fuels since the sources of these fuels have been depleted in the past few years. The most convenient process to produce biodiesel is the transesterification of triglycerides with an alcohol in the presence of a suitable catalyst. At the end of the reaction, two liquid phases comprised of biodiesel (main product), glycerol (by-product) and unreacted alcohol are co-exist. Phase equilibrium study is a tool to design the equipment that involved in the biodiesel production and purification processes. In this work, biodiesel was produced through the transesterification of linseed oil with methanol. Afterwards, the liquid–liquid equilibrium (LLE) data were measured for the ternary systems containing linseed oil biodiesel, methanol and glycerol at three different temperatures and atmospheric pressure. The binodal curves were determined by the cloud-point method in isothermal conditions. The adequacy of the experimental tie-lines has been confirmed using the Othmer–Tobias correlation. The results have been correlated using NRTL and UNIQUAC models. The binary interaction parameters of system components have been adjusted via an evolutionary algorithm so-called “BSOA” without and with closure equation. To predict the equilibrium composition, UNIFAC, UNIFAC-LLE, UNIFAC-DMD and UNIFAC-LBY models were used. Average deviations between the calculated and experimental data for NRTL, UNIQUAC, UNIFAC, UNIFAC-LLE, UNIFAC-DMD and UNIFAC-LBY were 1.574%, 1.380%, 3.187%, 3.164%, 3.881% and 3.960% respectively which show that UNIQUAC model represents the best correlation of experimental tie-lines. RMSD values have been improved by implementation of the closure equation.

Planet–Satellite Nanostructures Based on Block Copolymer‐Surfactant Nanoparticles Surface‐Decorated with Gold and Silver: A New Strategy for Interfacial Catalysis

AbstractGold (Au) and silver (Ag) nanoparticles (NPs) are covalently conjugated onto the surface of thiol‐functionalized block copolymer particles containing surfactant‐rich liquid crystalline cores. The resulting planet–satellite nanoconjugates display enhanced colloidal stability upon changes in solution pH or ionic strength and interfacial properties that result in the stabilization of oil‐in‐water emulsions. These biphasic systems are used as medium for catalyzed aerobic oxidation of benzyl alcohol to benzoic acid and the nanoconjugates display catalytic activity comparable to the single Ag and Au NPs in aqueous medium, with the advantage of an easier and more efficient separation of unreacted alcohol and product from reaction medium, making this the first report on interfacial gold‐ and silver‐catalyzed aerobic alcohol oxidation. These results, and the flexibility of the present approach, support the proposal of this methodology as a general platform for interfacial catalysis based on these novel nanomaterials.

LOW-WASTE TECHNOLOGY OF GLYCIDOL PRODUCTION BY PEROXIDE METHOD

A technological process of manufacturing glycidol designed for the production capacity of 10 thousand tons per year and consisting in the direct oxidation of allyl alcohol with an aqueous solution of hydrogen peroxide in the presence of nanostructured titanium silicate in methanol is proposed. Due to the exothermic process, the solvent is not only a homogenizer of the mixture of the initial reagents of the epoxy process - allyl alcohol and hydrogen peroxide ensuring their interaction on the surface of the solid catalyst: it also prevents overheating of the reaction mass. On the basis of the research trial of the process the optimal parameters of the process were determined: temperature 30-40 °C; pressure 0.25 MPa; the initial hydrogen peroxide : allyl alcohol ratio = 1:(3-4) mass., methanol concentration in the reaction mixture 12-13 mol/l. Hydrogen peroxide conversion is 98%, the yield of the glycidol - 94%, the selectivity is no less than 95%. The process includes three main stages: (1) raw materials preparation, (2) liquid-phase epoxidation of allyl alcohol, (3) distillation of the target product. The scheme involves recirculation of unreacted allyl alcohol and the solvent - methanol. The developed technological process provides the following indicators (per 1 t of commercial glycidol): consumption of allyl alcohol no more than 0.843 t; consumption of hydrogen peroxide no more than 0.50 t (calculated for 100% hydrogen peroxide); consumption of methanol is no more than 0.022 tons All the waste products correspond to the 3-rd or 4-th hazard class.

Development of technology for the alkylation of hydroquinone with aliphatic alcohols

The paper presents the results of research of technology of alkylation of hydroquinone, propyl, isopropyl, isobutyl and tert-butyl alcohols in the presence of concentrated phosphoric acid. The temperature of the alkylation reaction was maintained between 70–72 °С. On the basis of literature data and preliminary investigations the reaction was performed for 4 hours. Upon completion of the reaction, we removed the unreacted hydroquinone, aliphatic alcohol and phosphoric acid are added to a solution of distilled water (solvent corresponding connections) and sodium bicarbonate to slightly acidic (pH 5–6). For separation from the reaction medium of alkylhydroquinones in the reaction mixture was added benzene in which the original hydroquinone dissolves much less. Concentration of the benzene extract alkylhydroquinones conducted by Stripping the solvent under vacuum at temperatures above 70 °С in air atmosphere. Higher temperature vacuum distillation AIDS in the oxidation of alkylhydroquinones to alkylphenones. Precipitated after crystallization, alkylhydroquinones were dried under vacuum in a drying pistol at 56 °С. Dried products were identified by defining the melting temperature, the study of spectral characteristics and qualitative reactions with FeCl3. We also studied the solubility of alkylhydroquinones in various solvents, which showed low solubility of alkylhydroquinones in water, benzene, toluene and higher solubility in propyl and isopropyl alcohols and in acetone. Analysis of the results shows that the obtained alkylhydroquinones are not chemically pure compounds, and contain in their composition of admixture source of hydroquinone. Qualitative reactions of solutions of alkylhydroquinones with FeCl3 solution differ from the corresponding reaction of a solution of hydroquinone. The results of investigations of electronic absorption spectra of alkylhydroquinones and source of hydroquinone in isopropyl alcohol solution did not significantly differ from each other and have a maximum absorption at ? = 210 nm. From the presented investigations it follows that the maximum efficiency of the alkylation of hydroquinone was studied aliphatic alcohols in acidic medium is observed for t-butyl alcohol.

Ruthenium(II)‐Catalyzed Hydrogen Transfer/Annulation Cascade Processes between Alcohols and 2‐Nitrobenzaldehydes

AbstractThe synthesis of quinolines from alcohols and 2‐nitrobenzaldehydes is described. Unreactive alcohols and 2‐nitrobenzaldehydes were concurrently converted to the reactive reactants for a Friedländer annulation via a hydrogen transfer. Tris(triphenylphosphine)ruthenium(II) dichloride [Ru(PPh3)3Cl2] appeared to serve the dual role of an efficient hydrogen transfer catalyst and a suitable Friedländer annulation catalyst.magnified image

A new procedure for the treatment of an industrial waste containing flotation reagents

Flotation reagents can be transformed to industrial waste if they are stored for a long period of time. Also, if synthesis or drying process is not performed under defined conditions in industrial plants, which produce flotation reagents, batch of waste may arise and be stored as a waste. The chemical composition of this waste depends on the phase in which it was created, but typically includes: unreacted alkali hydroxide, solvent - alcohol and trithiocarbonate and oxidation product - dixanthogenate. In this paper a new laboratory procedure for the treatment of such wastes is described. The identification and separation of industrial waste components is also included. From the separated dixantogenate and xanthate a laboratory synthesis of thioncarbamates is given. In addition, a semi-industrial treatment of waste xanthate is presented. Synthesis of N-alkyl and N,N-dialkyl-O-isobutylthioncarbamates were obtained from the filtrate obtained in the first step. As a by-product, sodium thioglycolate was produced. This by-product is transformed to a thioglycolic acid by the addition of an acid. Also, the synthesis of thioncarbamates from dixanthogenates, isolated from industrial waste as a cake, is desribed. Described waste treatment is additionally interesting due to the production of sulphur as another by-product. Laboratory synthesis gave thioncarbamates in yields from 69.7 to 87.7 %, while the semi-industrial process for the selected batches produced thioncarbamates in yields from 74.2 to 80.5 %. Taking into account the importance of the synthesized compounds as selective flotation reagents, a new procedure of their synthesis from industrial waste is characterized by good yields and purity of the obtained compounds, the simplicity of process, low environmental impact and short reaction times of synthesis.

Scope and Mechanistic Analysis of the Enantioselective Synthesis of Allenes by Rhodium-Catalyzed Tandem Ylide Formation/[2,3]-Sigmatropic Rearrangement between Donor/Acceptor Carbenoids and Propargylic Alcohols

Rhodium-catalyzed reactions of tertiary propargylic alcohols with methyl aryl- and styryldiazoacetates result in tandem reactions, consisting of oxonium ylide formation followed by [2,3]-sigmatropic rearrangement. This process competes favorably with the standard O-H insertion reaction of carbenoids. The resulting allenes are produced with high enantioselectivity (88-98% ee) when the reaction is catalyzed by the dirhodium tetraprolinate complex, Rh(2)(S-DOSP)(4). Kinetic resolution is possible when racemic tertiary propargylic alcohols are used as substrates. Under the kinetic resolution conditions, the allenes are formed with good diastereoselectivity and enantioselectivity (up to 6.1:1 dr, 88-93% ee), and the unreacted alcohols are enantioenriched to 65-95% ee. Computational studies reveal that the high asymmetric induction is obtained via an organized transition state involving a two-point attachment: ylide formation between the alcohol oxygen and the carbenoid and hydrogen bonding of the alcohol to a carboxylate ligand. The 2,3-sigmatropic rearrangement proceeds through initial cleavage of the O-H bond to generate an intermediate with close-lying open-shell singlet, triplet, and closed-shell singlet electronic states. This intermediate would have significant diradical character, which is consistent with the observation that the 2,3-sigmatropic rearrangement is favored with donor/acceptor carbenoids and more highly functionalized propargylic alcohols.

Kinetic Resolution of Aryl Alkenylcarbinols Catalyzed by Fc‐PIP

AbstractAn effective kinetic resolution of a variety of aryl alkenylcarbinols catalyzed by nonenzymatic acyl transfer catalyst Fc‐PIP was developed, affording corresponding unreacted alcohols in good to excellent ee value up to 99% and with selectivity factors up to 24.

ChemInform Abstract: Optically Pure Bulky (Hetero)arylalkyl Carbinols via Kinetic Resolution.

AbstractA planar chiral nucleophilic ferrocene catalyst is employed in the kinetic resolution of bulky arylalkyl carbinols (I) to afford unreacted alcohols (R)‐I with extremely high enantiomeric excess in ideal conversions ranging from 50—56%.

Optically pure bulky (hetero)arylalkyl carbinols via kinetic resolution

Planar chiral nucleophilic catalyst Fc-PIP was employed in the kinetic resolution of bulky (hetero)arylalkyl carbinols delivering unreacted alcohols with extremely high enantiomeric excess (>99.0% ees) in ideal conversions ranging from 50.4-56.7%.

Enzyme‐Catalyzed Stereoselective Synthesis of Two Novel Carbasugar Derivatives

AbstractEnzymatic resolution of racemic 1,4,5,6‐tetrachloro‐2‐(hydroxymethyl)‐7,7‐dimethoxybicyclo[2.2.1]hept‐5‐ene (rac‐1) using various lipases in vinyl acetate as acetyl source was studied. The obtained enantiomerically enriched (+)‐(1,4,5,6‐tetrachloro‐7,7‐dimethoxybicyclo[2.2.1]hept‐5‐en‐2‐yl)methyl acetate ((+)‐2; 94% ee), upon treatment with Na in liquid NH3, followed by Amberlyst‐15 resin in acetone, provided (−)‐5‐(hydroxymethyl)bicyclo[2.2.1]hept‐2‐en‐7‐one ((−)‐7), which is a valuable precursor for the synthesis of carbasugar derivatives. Subsequent Baeyer–Villiger oxidation afforded a nonseparable mixture of bicyclic lactones, which was subjected to LiAlH4 reduction and then acetylation. The resultant compounds (−)‐11 and (+)‐12 were submitted to a cis‐hydroxylation reaction, followed by acetylation, to afford the novel carbasugar derivatives (1S,2R,3S,4S,5S)‐4,5‐bis(acetoxymethyl)cyclohexane‐1,2,3‐triyl triacetate ((−)‐(13)) and (1R,3R,4R,6R)‐4,6‐bis(acetoxymethyl)cyclohexane‐1,2,3‐triyl triacetate ((−)‐(14)), respectively, with pseudo‐C2‐symmetric configuration. The absolute configuration of enantiomerically enriched unreacted alcohol (−)‐1 (68% ee) was determined by X‐ray single‐crystal analysis by anchoring optically pure (R)‐1‐phenylethanamine. Based on the configurational correlation between (−)‐1 and (+)‐2, the absolute configuration of (+)‐2 was determined as (1R,2R,4S).