Homologous Series Of N-alcohols Research Articles

Heterosegmental Modeling of Long-Chain Molecules and Related Mixtures Using PC-SAFT: 2. Associating Compounds

Renewable resources such as natural fats and oils are progressively used as feedstock for the chemical industry due to the depletion of fossil resources. Natural fats and oils primarily comprise triglycerides that are the basis for long-chain molecules such as fatty alcohols, fatty amines, and fatty acids. The saturated representatives of these individual families are composed of an identical functional head moiety and an n-alkylic residue that only varies in chain length within a homologous series. In the first part of our work (Haarmann et al., Ind. Eng. Chem. Res. 2019, 58 (7), 2551−2574) a heterosegmental approach of the Perturbed Chain Statistical Associating Fluid Theory was proposed with the focus on polar long-chain molecules. Within the heterosegmental approach, a (saturated and linear) long-chain molecule is modeled as comprising a tail domain described as an n-alkane and a universal head domain. In this work, this heterosegmental approach is extended to associating long-chain molecules with the focus on the homologous series of n-alcohols, n-amines, and n-alkyl carboxylic acids. Applying the heterosegmental approach, vapor pressures and saturated-liquid densities of the pure associating long-chain compounds were predicted in very good agreement with the experimental data. The same holds for the molar excess enthalpies of the binary mixtures long-chain compound + n-alkane, which were modeled for a broad range of chain lengths without using any additional model parameter. Moreover, the mutual solubilities in the binary mixtures long-chain compound + water could be predicted in remarkable agreement with the available experimental data for a broad range of chain lengths of the long-chain compounds.

Kinetic solvation and electrical conductance of proton in infinitely diluted solutions of hydrogen halides in primary alcohols and in water: influence of temperature and solvent

Until now, there is no comprehensive quantitative description of the forms of existence of the solvated proton in protic solvents. The research of the mechanism of its conductance in a such solvents also is far from completion. In the present paper we attempt to estimate two contributions into limiting molar electrical conductance (LMEC) of proton λi0(H+)=λi0(L+)+λi0(Z+) in n-alcohols and water at 278.15–328.15K. Our estimations are based on our own conductometric data on hydrogen halides solutions and literature data on some 1-1 electrolytes in water. The first contribution corresponds to the lyonium ion L+ (or MH+, where M is solvent molecule), and the second one – to the so-called Zundel ion Z+ (or M2H+). We also have divided each of these contributions into two parts in accordance with known proton transfer mechanisms – hydrodynamic and prototropic (relay), so that the total conductance of proton can be represented as the sum of four terms: λi0(H+)=λi0(L+)hydr+λi0(L+)rel+λi0(Z+)hydr+λi0(Z+)rel, and we have evaluated each of them. Then the friction coefficients of ions (ζat(L+) and ζat(Z+)) have been calculated from values of the hydrodynamic terms. This allows to distinguish the negative solvation from positive one by the ζat sign. In result, Z+ has found to be solvated negatively in all the solvents mentioned, but L+ has such solvation only in water, in contrast to its weak positive solvation in n-alcohols. The alternating sign of ζat suggests this coefficient as a sum of two parts: a negative part ζatMM, and positive one ζatIM, which also have been calculated by us in accordance with Samoilov's kinetic solvation theory. Moreover, analyzing ζat(L+) dependence on the solvent and temperature, we became able to confirm the alternation effect in the homologous series of n-alcohols and explain it. Generally, this phenomenon can be detected experimentally only by highly sensitive methods of spectroscopy. In conclusion, the details of the mechanism of proton transfer in protic solvents have been discussed considering ab initio optimized geometry (B3LYP/6-31+G(d,p), Gaussian’03) of proton-contained clusters.

Effect of n-Alcohols on the Stability of Bubbles

A new method of characterizing the effect of solutes on the stability of bubbles in aqueous media is described. Single bubbles were allowed to rise to the surface of an aqueous solution. The time between the arrival at the surface and the bursting of the bubble at the interface was measured as a function of solute concentration, using a laser disruption technique. The effect of a homologous series of n-alcohols (C1 to C8) on the persistence time was measured in aqueous solution. With increasing concentration of a particular solute, the persistence time increased up to a point and then declined. The magnitude of the persistence time was found to increase with increasing numbers of carbon atoms in the molecule. The concentration Cmax at which the maximum persistence time was observed was found to be independent of the bubble size. It decreased uniformly as the carbon number increased and was well correlated by the function γ1/2 (dγ/dc)−2. There was no apparent correlation with the surface excess at maximum persistence time.

Effect of contaminant hydrophobicity on hydrogen peroxide dosage requirements in the Fenton-like treatment of soils

A homologous series of n-alcohols was used as model contaminants to investigate the effect of hydrophobicity on the hydrogen peroxide concentration necessary in Fenton-like treatment for near-complete (>99%) destruction of compounds sorbed to soil. These probe compounds were selected because they exhibit equal reactivities with hydroxyl radicals, but have varied hydrophobicities. The standard Fenton reaction was first used to confirm equal hydroxyl radical reactivity for the n-alcohols. Central composite rotatable design experiments were then used to determine the conditions in an iron(III)–hydrogen peroxide system that resulted in 99% degradation of each of the probe compounds when sorbed to soil. The hydrogen peroxide concentrations required for 99% destruction of the sorbed compounds increased with probe compound hydrophobicity. Furthermore, hydrogen peroxide concentration requirements were directly proportional to the log octanol–water partition coefficients (log K OW) of each probe compound. This quantitative relationship may not be directly applicable to other organic contaminants, but a strong correlation between log K OW and hydrogen peroxide requirements for other contaminants will likely be found. These results confirm that hydrogen peroxide requirements for soil treatment increase as a function of contaminant hydrophobicity and provide a basis for the development of an algorithm for hydrogen peroxide requirements when modified Fenton’s reagent is used for in situ chemical oxidation (ISCO).

Interactions between native cyclodextrins and n-alcohols studied using thermostated thin-layer chromatography

Using thermostated thin-layer chromatography, the retention behavior of α-, β- and γ-cyclodextrin on a C 18 stationary phase was studied. As mobile phases, a homologous series of n-alcohols, from ethanol to pentanol, and their mixtures with water were examined. Chromatographic experiments were performed either at a constant temperature (30°C) and over a wide range of binary mixtures (0–100%, v/v), for ethanol and propanol, as well as at fixed mobile phase composition and different temperatures from 5°C to 60°C. Using isoelution binary mobile phases, the effect of temperature on retention of cyclodextrins was examined. Results were compared with chromatographic retention data from previously reported work in which methanol–water binary phases were used. From linear Van ‘t Hoff plots thermodynamic parameters such as the change of enthalpy (Δ H 0) and the change of entropy (Δ S 0) were estimated. In each case the sign of the calculated parameters is negative. Nonlinearities of Van ‘t Hoff plots were observed when propanol or butanol was used as a component of binary mobile phase.

Effects of general anesthetics on the bacterial luciferase enzyme from Vibrio harveyi: an anesthetic target site with differential sensitivity

The effects of a diverse range of 36 general anesthetics and anesthetic-like compounds on a highly purified preparation of the bacterial luciferase enzyme from Vibrio harveyi have been investigated. Under conditions where the flavin site was saturated, almost all of the anesthetics inhibited the peak enzyme activity and slowed the rate of decay. However, a small number of the more polar agents only inhibited at high concentrations, while stimulating activity at lower concentrations. The inhibition was found to be competitive in nature, with the anesthetics acting by competing for the binding of the aldehyde substrate n-decanal. The anesthetic binding site on the enzyme could accommodate only a single molecule of a large anesthetic but more than one molecule of a small anesthetic, consistent with the site having circumscribed dimensions. The homologous series of n-alcohols and n-alkanes exhibited cutoffs in inhibitory potency, but these cutoffs occurred at very different chain lengths (about C10 for the n-alkanes and C15 for the n-alcohols), mimicking similar cutoffs observed for general anesthetic potencies in animals. Binding constants determined from peak height measurements showed that the inhibitor binding site was predominantly hydrophobic (with a mean delta delta G CH2 of -5.0 kJ/mol), but fluctuations in the binding constants with chain length revealed regions in the binding site with polar characteristics. Binding constants to an intermediate form of the enzyme (intermediate II) were also determined, and these confirmed the principal features of the binding site deduced from the peak height measurements. The long-chain compounds, however, bound considerably tighter to the intermediate II form of the enzyme, and this was shown to account for the biphasic decay kinetics that were observed with these compounds. Overall, there was poor agreement between the EC50 concentrations for inhibiting the luciferase enzyme from V. harveyi and those which induce general anesthesia in animals, with bulky compounds being much less potent, and moderately long chain alcohols being much more potent, as luciferase inhibitors than as general anesthetics.

Characterizing the surface contact behaviour of ceramics

The effect of chemical environment (a homologous series ofn-alcohols) on the near-surface hardness and wear behaviour of two glass-bonded ceramics has been investigated. A change by upto a factor of two in both these parameters may be observed, with a good correlation between them. The indentation fracture behaviour of one material was also studied, and the environmental dependence of crack length suggests a slow crack-growth mechanism. The results show that the near-surface mechanical properties of ceramics may be modified by environmental means.

Correlations between Van der Waals' volume and retention index general equation applicable to different homologous series

Correlations between retention index (RI) and Van der Waals' volume (VW) in homologous series of n-alcohols, n-aldehydes and esters are studied on the stationary phases Carbowax 1540 and squalane. Influence of functional groups is quantified and a method for obtaining one general equation, valid for an indeterminate number of homologous series, is proposed.

Prediction of equilibrium properties of single and binary n-alcohols

Abstract A description of equilibrium quantities, including the excess functions of mixing, was possible using a small number of parameters essentially obtainable from the properties of pure components. For this purpose, molecules were divided into segments, segments related to graph points, interesting walks on graphs counted, and thermodynamic properties expressed in terms of interactions of pairs of walks. For such an approach, the association of alcohols is irrelevant and no reference to association schemes was made. “Odd” behaviour of the lower members of the homologous series of n-alcohols was discussed in terms of walks on corresponding graphs.