Alkyl Group Of Alcohols Research Articles

Combination of linear solvation energy and linear free-energy relationships to aid the prediction of reaction kinetics: Application to the solvolysis of 5-HMF by alcohol to levulinate

In the context of cellulose valorization, we studied the kinetics of levulinates synthesis via the solvolysis of 5-HMF by alcohol over Amberlite IR-120. The alcohol plays a double role; it is a reactant and acts as the solvent. In the literature, kinetic models were developed for each type of alcohol, but there were no models combining the dual effect of alcohol alkyl group substituent (ROH) as a reactant and solvent. Such global kinetic models can save time and optimize a process by considering the solvent effect. This effect was taken into account via the Kamlet–Abboud–Taft and Taft equations, using Bayesian inference. We studied the kinetics of levulinate production from 5-HMF in a reaction mixture made of alcohol and GVL within a temperature range from 80 to 115 °C. The following alcohols were used: methanol, ethanol, propanol, butanol, pentanol, and hexanol. It was found that the rate of alkyl levulinate production increases faster in alcohol reaction medium compared to water reaction medium, and increases when increasing the alkyl group substitution (rMLMethanol>rELEthanol>rPLPropanol>rBLButanol>rPeLPentanol>rHeLHexanol>rLAWater). Among the global kinetic models developed in this study, the one that neglects the side reaction of humins was found to be the most reliable.

Investigation of the Phase Formation Mechanism of the Sugar-Based Natural Deep Eutectic Solvent + Water-Soluble Alcohol + Water Aqueous Biphasic System Based on the Excluded Volume Theory

To investigate the phase formation mechanism of sugar-based natural deep eutectic solvent (DES) aqueous biphasic systems, an excluded volume theory (EEV) model was extended to the sugar-based (sucrose, glucose, fructose)-choline chloride DES + tert-butyl alcohol and isopropyl alcohol + water systems. In this paper, phase density measurement of sugar-based natural deep eutectic solvents (NADESs) + water-soluble alcohols + water systems revealed that the densities of NADES-rich and alcohol-rich phase presented significant differences. On the basis of these results, a modified EEV model was correlated with the density and phase equilibrium data of each system. Subsequently, the parameters of the excluded volume obtained were used to quantify the interaction force between the NADES and alcohol, and the relationship between parameters and functional groups of phase components was used to explore the mechanism of phase formation and predict the possible liquid structure of the DES-rich phase. The analysis of the Va – DES – w* and fa – DES – w values showed that the interaction between the components of each system was influenced by the functional groups of hydrogen bond donors (HBDs) and alcohols, and it was beneficial to reduce the compatibility of the system and the space unfilled of tight packing of molecules by increasing the number of hydroxyl groups of HBDs and alkyl groups of alcohol, leading to improvement of the phase formation ability. From the analysis of the parameters given by the EEV model, the adjustment of the number of hydroxyl groups of HBDs and alkyl groups of alcohols was beneficial to regulate the biphasic coexistence region of sugar-based DES/alcohol systems.

Difference in the hydration state of water at the hydrophobic interface of structural isomers of propanol investigated by U.V visible absorption and Raman spectroscopic study

In this work, the nature of hydration shell water around hydrophobic groups of alcohol has been investigated by studying the U.V visible absorption energy shift of p-nitro-aniline upon interaction with water-alcohol mixture in different proportion. Analysis shows that, at low mole fraction of alcohol the absorption energy shift with composition of alcohol-water mixture originates from the interaction of hydrophobically modified water with PNA. It is further observed that, the absorption energy changes nonlinearly with the chain length of alkyl group of alcohol. From Raman studies it is apparent that, the absorption energy shift originates from the changing population of dangling OH interacting with PNA. The central part of the study has been to investigate the difference in the hydrophobic environment due to variation in the arrangement of hydrophobic groups in propanol. The U.V visible absorption studies of PNA in 1-propanol and 2-propanol water mixture show that 1-propanol bears higher population of dangling OH compared to 2-propanol. In addition, we have also performed Raman spectroscopic studies in the region of OH stretch. The spectra of hydration shell water are extracted by RD-SCF method. The characteristic peak due to dangling OH was analyzed and it also shows 1-propanol to possess relatively higher amount of dangling OH compared to 2-propanol. This joint study confirms that arrangement of hydrophobic moiety in small molecules can affect the water hydrogen bonding of water at the hydrophobic interface.

Interaction of Water at the Hydrophobic Interface of Alkyl Group of Alcohol with p‐Nitro‐Aniline Charge Transfer State

AbstractThe evolution of photo‐induced intra molecular charge transfer (ICT) transition energy of p‐nitro‐aniline (PNA), with respect to the mole fraction of alcohol in alcohol water mixture has been used to study, the interaction of hydrophobic hydration ‐shell of linear alcohols with PNA‐ICT state. The linear alcohol ranges from methanol to propanol. The plot of absorption energy of PNA charge transfer transition versus mole fraction of alcohol shows the following features. At lower mole fraction of alcohol, the absorption energy of PNA versus mole‐fraction of alcohol plot at first, decreases below the absorption energy of PNA recorded in pure water and alcohol, goes through a minimum and then increases. Similar behaviour is obtained even after subtracting the contribution from dielectric non‐ideality. The behaviour at lower mole fraction thus indicates the modification of specific interaction of PNA with water due to the presence of alcohol. Further, the absorption energy minimum shifts towards lower mole fraction of alcohol as the chain length of alcohol increases. These results, thus reveals the interaction of PNA with the modified water structure at the hydrophobic interface of alkyl group and supports the current understanding of hydrophobic hydration. To our knowledge, this study for the first time reveals that, hydration shell around hydrophobic group has higher ability to stabilize the PNA‐ICT state by hydrogen bonding interaction compared to bulk water.

Mass density, sound velocity, mixing enthalpy, 1H NMR, Ab initio calculations and intermolecular interactions in binary mixtures of N-methylimidazole + water, +methanol, +ethanol, +1-propanol, +2-propanol

Over a full molar fraction range, for binary mixtures of x N-methylimidazole (hereafter abbreviated to N-mim) + (1 − x) water, +methanol, +ethanol, +1-propanol, +2-propanol, the mass density and sound velocity at (288.15, 298.15, 308.15, 318.15, 328.15) K, the mixing enthalpy at 298.15 K, and 1H NMR measurements, combined with the Ab initio calculations, have been carried out.The excess molar volume, excess average volume expansivity, excess sound velocity, excess isentropic compressibility, and the molar mixing enthalpy were calculated and fitted to a Redlich-Kister equation. The partial molar enthalpy of N-mim, the difference between the partial molar volume and the molar volume of N-mim, and the protons chemical shift changes were calculated and compared. The chemical shifts of N-mim protons, hydroxyl protons, and α-H (proton on the carbon atom next to the –OH group) of alcohols in the mixtures containing alcohols were explained by a model proposed by Gupta et al..The properties indicate that the intermolecular interactions between unlike molecules are stronger than those between like molecules. An increase in temperature has a greater influence on the mixture containing water than on pure components, and has a greater influence on pure components than on mixtures containing alcohols. The predominant interactions between unlike molecules are hydrogen-bonded complexes in the mixture containing water, and are N-mim: alcohols = 1:1 hydrogen-bonded networks in the mixtures containing alcohols, where the alkyl groups of alcohols are electron-withdrawing groups, and the methyl group of N-mim is an electron-donating group. Ab initio calculations proved that the N⋯HO hydrogen bond in the mixtures is more stable and stronger than HO⋯HO in pure water or in pure alcohols and N⋯HC in pure N-mim. The strength sequence of the intermolecular interactions between unlike molecules for the mixtures at 298.15 K is N-mim–water > N-mim–methanol > N-mim–ethanol > N-mim–1-propanol ≥ N-mim–2-propanol.

Microstructure tuning of mesoporous silica prepared by evaporation-induced self-assembly processes: interactions among solvent evaporation, micelle formation/packing and sol condensation

By varying the vapor pressure of solvents through changing the alkyl length of aliphatic alcohols or the aging temperature, the microstructures, including mesopore ordering length, porosity, and specific surface area, of silica templates are controllable in an evaporation-induced self-assembly (EISA) process. The microstructures of various silica powders are systematically characterized and compared by the small-angle X-ray scattering (SAXS), nitrogen adsorption/desorption isotherms, as well as scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images. The microstructure ordering length of silica powders is found to decrease with reduction of the solvent evaporation rate tuned by the length of alkyl groups of alcohols, which is confirmed by the almost identical microstructure of silica powders prepared by using methanol and tetrahydrofuran (THF) which exhibit similar vapor pressures. The rate of micelle formation relative to the rate of silica precursor condensation, strongly depending on the solvent evaporation rate, determines the resultant organization of micelles and may cause morphological distortion and microdomain disorientation of silica templates. This concept is confirmed by the presence of completely and partially ordered microstructures of silica powders synthesized from the ethanol- and butanol-based precursor solutions, respectively, which are dried completely at a higher temperature in the aging process. The microstructure of mesoporous silica can thus be simply tuned by varying solvents and aging temperatures in the EISA process, which are promising for many applications.

Effect of the substituent position at the heterocycle on proton transfer from alcohols to the excited molecules of 1,2-dihydroquinolines

A novel compound 1,2,2,3-tetramethyl-1,2-dihydroquinoline (1223TMDQ) was synthesized, and the products of its steady-state photolysis in water, MeOH, EtOH, trifluoroethanol (TFE), PrnOH, and BuiOH were analyzed by 1H NMR and mass-spectrometry. The corresponding adducts with water and alcohols were identified. The presence of the adducts for alcohols with a number of carbon atoms n > 1 distinguishes 1223TMDQ from 2,2,4-trimethyl-1,2-dihydroquinolines with methyl-, alkoxy-, and hydroxy-substituents at positions 1, 6, and 8, for which the formation of adducts was observed only in the presence of water and MeOH. The results were interpreted in terms of the effect of steric hindrance caused by substituents in the heterocycle and increasing size of the alkyl group of alcohol on proton transfer from a solvent to the molecule of 1,2-dihydroquinoline, which occurs in the complex between the solvent and the dihydroquinoline molecule in the excited singlet state. It was shown that the main steric hindrance for the photoinduced proton transfer in 2,2,4-substituted 1,2-dihydroquinolines is the substituent at position C(4) of the heterocycle.

Hydrogen bonding interaction between N-methylformamide and alcohols

The hydrogen bonding interactions between N-methylformamide and primary, secondary, and tertiary alcohols have been studied using the FTIR spectroscopic method. The most likely association complex between alcohol and N-methylformamide is the 1:1 stoichiometric complex formed between the hydroxyl group of alcohol and the carbonyl group of N-methylformamide. The formation constant of the 1:1 complexes has been calculated using the Nash method. It appears that the primary alcohols have larger formation constant compared with the secondary and tertiary alcohols. The results showed that the proton-donating ability of the alcohols decreased in the order: primary>secondary>tertiary, and that the association constant increased with the increase in carbon chain of the alkyl group of alcohols.

Role of steric hindrance in photoinduced proton transfer from solvent to excited molecules of 1,2-dihydroquinolines

It was shown that the photolysis of 1,2,6-trimethyl-1,2-dihydroquinoline (126TMDHQ) in water, methanol, ethanol, and isopropanol affords the corresponding adducts of water and the alcohols, unlike the case of 2,2,4-trimethyl-1,2-dihydroquinolines bearing the methyl, alkoxyl, and hydroxyl substituents in the 1-, 6-, and 8-positions, which were previously found to form adducts only in the presence of water and MeOH. The quantum yield of the 126TMDQ photolysis (Φ) in this solvent series changes as ΦMeOH:ΦEtOH:ΦPrOH = 10:3:1. The results were rationalized in terms of the effect of steric hindrance caused by substituents on the heterocycle and increasing size of the alcohol alkyl group on proton transfer from the solvent to the 1,2-dihydroquinoline molecule in the excited singlet state. The existence of two adduct isomers was revealed. The preferential formation of one of the isomers was considered from the standpoint of carbocation accessibility to the solvent by nucleophilic attack.

Hydrogen Bonding Interaction between Methyl Methacrylate and Alcohols

The hydrogen bonding between methyl methacrylate and primary, secondary and tertiary alcohols has been studied by using FTIR spectroscopic method. The most likely association complex between alcohol and methyl methacrylate is 1 : 1 stoichiometric complex through the hydroxyl group of alcohol and the carbonyl group of methyl methacrylate. The formation constant of the 1 : 1 complexes has been calculated using Nash method. It appears that the primary alcohols have larger formation constant than the secondary and tertiary alcohols. The results show that the proton donating power of the alcohols decreases in the order primary > secondary > tertiary and the association constant increases with the increase in carbon chain of the alkyl group of alcohols.

Synthesis of a cis-rich, living poly[(o-methylphenyl)acetylene] by use of the MoOCl4-n-Bu4Sn-EtOH catalyst

Polymerization of (o-methylphenyl)acetylene (o-MePA) by MoOCl4-n-Bu4Sn-EtOH catalyst in toluene at 0°C provided a cis-rich living polymer; cis 77%, M w/M n=1.21. The polymerization at -30°C gave results similar to those for 0°C, whereas the polymer obtained at 30°C exhibited a broader molecular weight distribution (MWD) and a lower cis content. Among several organotin compounds, only n-Bu4Sn was effective for the living polymerization of o-MePA. The bulkier the alkyl group of alcohols as the third catalyst component, the broader the MWD of the polymer, while the geometrical structure was not affected by the alcohols.

ChemInform Abstract: Preparation of 2‐(Alkylseleno)benzothiazoles. Direct Incorporation of the Alkyl Group of Alcohols into Benzothiazolylseleno Residue.

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Preparation of 2-(Alkylseleno)benzothiazoles. Direct Incorporation of the Alkyl Group of Alcohols into Benzothiazolylseleno Residue

Abstract Reaction of alcohols with 2-(1,2-diphenyl-2-oxoethylseleno)benzothiazole in the presence of tributylphosphine gave the corresponding 2-alkylselenobenzothiazoles, where inversion of the secondary carbinol center of the alcohols took place. 1,3-Butanediol reacted at the primary hydroxyl group, while 1-phenyl-1,2-ethanediol reacted at the secondary hydroxyl group.

The Chlorination of Vinyl Compounds in Alcohols

Abstract Upon the chlorination of vinyl compounds in alcohols, the reaction products were composed of 2-alkoxy-1-chloro compound (A), 1-alkoxy-2-chloro compound (B) and vicinal dichloride (C). Various vinyl compounds were chlorinated in alcohols at 40 °C in order to elucidate the effect of their molecular structure on the product distribution. The A/(A+B) was inversely proportional to the relative rate of ordinary chlorination in carbon tetrachloride. The A/(A+B) for the chlorination of allyl chloride in methanol was little affected by the reaction conditions: (1) reaction temperature, (2) mole ratio, and (3) elapse of time. However, the A/(A+B) increased with increasing Es value of the alkyl group of alcohol.

Site Selectivity in the Gas‐Phase Ionic Phenylation of Alcohols and Alkyl Chlorides

AbstractFree, unsolvated phenylium ions formed by the spontaneous β decay of [1,4‐3H2]benzene have been allowed to react with gaseous alcohols (ROH: R = Et, CF3CH2, Pr, or i‐Pr; partial pressure: 3–56 Torr) and alkyl chlorides (R′Cl: R′ = Pr, i‐Pr, or Bu; partial pressure: 20–450 Torr), in the presence of a thermal radical scavenger (O2: 4 Torr). Phenylium ion confirms its considerable site selectivity, demonstrated by the distinct preference toward the n‐centre of the substrate (46–100%), although significant insertion into the alkyl group of alcohols is observed as well. Phenylium ion displays significant positional selectivity even between different n‐type sites in a bidentate molecule such as CF3CH2OH. An affinity F < O < Cl trend is observed, which indicates a direct relationship between the polarizability of the n‐centre of the molecule and its orienting properties toward phenylium ion. The stability features of the ionic intermediates from addition of phenylium ion with ROH or R′Cl have been evaluated, as well as their fragmentation and isomerization mechanisms. The behaviour of phenylium ion toward the selected substrates in the gas phase is discussed and compared with previous mechanistic hypotheses from related nuclear‐decay studies.

Interaction between flavins and alcohols

The effect of alcohols on the spectral properties of riboflavin derivatives in non-polar solvent was studied by various spectroscopic methods in order to support the view point that alcohol may directly interact with the isoalloxazine moiety of FAD and enhance the catalytic activity of D-amino acid oxidase (DAAO). The most likely association complex between alcohol and riboflavin is 1 : 1 stoichiometric complex through the 3-N imino and the 2-C carbonyl groups of the isoalloxazine ring and the hydroxyl group of alcohols. It appears that methanol has a larger association constant than any other alcohols, and the association constant decreases with the increase in carbon number and with the steric requirement of the alkyl group of alcohols.

Infrared studies of fluoroalcohol-base complexes in the gas phase, carbon tetrachloride solutions and argon matrices

Hydrogen bonded complexes of fluoroalcohols with oxygen-containing bases like dimethyl ether and alkanols have been investigated in argon matrices, in CCl 4 solutions and in the gas phase. The increase of the proton donor capacities with succesive substitution of fluorine atoms into the alkyl group of alcohols is indicated by a strong increase of the shift Δν of the OH stretching frequency in the complexes. For alkanols as acceptors, an increase of Δν is observed along the series CH 3OH, CH 3CH 2OH, (CH 3) 2CHOH, and (CH 3) 3CHOH. The frequency shifts Δν increase as one passes from the gas phase to CCl 4 solutions and argon matrices.

Interaction of flavins and some alcohols on the molecular level

The effect of some alcohols on the riboflavin derivatives in non-polar solvent was studied by various spectroscopic method in order to support the viewpoint that alcohol may directly interact with the isoalloxazine moiety of FAD, the coenzyme of D-amino-acid oxidase. The most possible association complex between alcohol and riboflavin is the 1∶1 complex through the 2-C carbonyl function of the isoalloxazine ring and the hydroxyl proton of alcohol. It is appeared that methanol has a larger association constant than any other alcohols, and the association constant decreases with the carbon number increases and being bulkier in the alkyl group of alcohols.

Equilibria and Substrate Specificity Studies with Alcohol Dehydrogenases

Abstract While secondary alcohols and NAD+, and ketones and NADH react much slowly than the ethanol–acetaldehyde system in the presence of yeast and liver alcohol dehydrogenases, by starting near equilibrium concentrations, it has been shown that expected thermodynamic equilibria are obtained. With liver ADH, cycloalkanols are remarkably reactive, while with yeast ADH those with six or more carbon atoms in the ring are unreactive. Horse liver ADH shows stereospecificity for 2-octanol, but no stereospecificity for 2-butanol. On the other hand, yeast ADH shows the same stereoselectivity for both alcohols. In the presence of yeast ADH, R(−)-isomers of 2-butanol, 2-octanol and 1-methoxy-2-propanol are not reactive, comparing to the big reactivity of S(+)-isomers of these alcohols, but R(−)-isomer of propylene glycol is also slightly reactive as S(+)-isomer. Further, the reactivity of secondary alcohols with NAD+ in the presence of liver ADH is following, 2-octanol>2-butanol>2-propanol. These results suggest that horse liver ADH is much less sterically hindered at its active site than yeast ADH and that not only the steric factor but also hydrophobic bonding between the end alkyl group of alcohol and the hydrophobic region of enzyme might be another important factor to determine stereospecificity and reactivity of enzyme.

Order of Quencher Participation in Photochemistry. I. Proton Transfer from the Excited p-Hydroxybenzophenone in Mixed Solvents of Cyclohexane and Alcohols

Abstract The change in the absorption spectrum of p-hydroxybenzophenone (HOBP) and relative quantum yields Φrel for the photoreduction of HOBP have been studied in mixed solvents consisting of cyclohexane and four kinds of alcohol. The change in absorption spectrum occurs in two steps with methanol, ethanol, and 2-propanol, suggesting the following equilibria, HOBP+S\leftrightharpoonsA, and A+S\leftrightharpoonsB (S, alcohol molecule). Φrel changes in two steps with methanol and ethanol and in one step with 2-propanol and amyl alcohol roughly in line with the spectral change. The changes in Φrel have been interpreted to be due to the deprotonation of HOBP. Φrel=1⁄(1+K[S]n) holds for them with n=5.5 for 2-propanol and n=1 for other alcohols. A linear relation holds between 1⁄(n−1)logK and Hammett’s constant of alkyl group of alcohols, suggesting that the deprotonation tendency depends upon the specific interaction between alcohol molecules. The reactivity of A-species is considered to depend largely on the dielectric nature of the solvent.