Abstract  The liquid-phase mercury-photosensitized luminescence of tert-butyl alcohol (TL)-tert-butylamine (TM) mixtures has been investigated by a steady-state illumination method over a wide range of substrate concentrations. The emission bands from exciplexes (HgTL* and HgTM*) between an excited mercury atom and an alcohol or an amine molecule were observed at about 330 nm and 370 nm, respectively, in TL and TM solutions in cyclohexane. Two other bands appeared at 405 nm and 455 nm for TM at high concentrations. These bands were previously assigned to two types of 1:2 exciplexes (HgTM(2)* and HgTM(2)**). In TL-TM mixed solutions, a new band appeared at about 400 nm. The intensity of this band increased with increasing concentrations of TL and TM. This band was attributed to an exciplex with mixed ligands (HgTLTM*). This band was observed for the first time in this study. The energized intermediate, (HgTLTM*)(not equal), formed between HgAL* and AM can be effectively stabilized by collisions with solvent molecules in solution, while it decomposes to HgAM* and AL in the gas phase. The results for TL-TM mixtures can be explained by the proposed reaction mechanism.

Abstract  This work concerns a comparison of the hydration properties and self-association behavior in aqueous solution of three biologically relevant simple molecules: tert-butyl alcohol (TBA), trimethylamine-n-oxide (TMAO), and glycine betaine (GB). These molecules were used as a model to study hydrophobic behavior in water solutions. In particular, water perturbation induced by TBA, TMAO, and GB molecules was studied as a function of the solute molar fraction X(2) (0 < X(2) < 0.04) by Raman spectra of water in the fundamental OH-stretching region (3,800-2,800 cm(-1)). Furthermore, possible hydrophobic clustering of these molecules was investigated by studying the behavior of the alkyl CH stretching band in the 3,100-2,900 cm(-1) frequency region as a function of X(2). To establish the existence of a correlation between the effects of these three solutes on the micellization process and changes in the properties of the solvent, the behavior of the critical micelle concentration of sodium dodecyl sulfate was also investigated as a function of the added amount of TBA, TMAO, and GB. On the whole, these data show that there is no direct correlation between a solute's effect on the water structure and its effect on micelle or protein stability. Results indicate that, while TBA starts to self-aggregate at approximately X(2) = 0.025, both TMAO and GB do not exhibit any significant self-aggregation up to the highest concentration considered. In addition, nonadditive perturbations of the H-bonded networks of solvent water are observed in the case of TBA solutions, but are absent in both the TMAO and GB cases. The absence of these nonlinear effects in TMAO and GB water solutions allow for tracing the microscopical mechanism of the neutrality of these osmolytes toward hydrophobic effects. This confers the compatibility to these two osmolytes, which can be accumulated at high concentrations without interfering with biochemical processes in the cell.

Abstract  This paper describes the degradation of tert-butyl alcohol (TBA) in dilute aqueous solution by an O3/UV process. The degradation process was investigated experimentally in a semi-batch reactor under various operational conditions, i.e., ozone gas (O3) dosage, UV light intensity, and water quality in terms of varying bicarbonate concentration. TBA was oxidized rapidly in the O3/UV system, and acetone, hydroxy-iso-butyraldehyde, and formaldehyde were identified as primary intermediates, whereas pyruvaldehyde and acetic, formic, pyruvic, and oxalic acids were generated as a result of further oxidation process. A good organic carbon balance was obtained, indicating that most reaction intermediates have been identified and quantified.

Abstract  Quasielastic neutron scattering has been used to investigate the dynamical behavior of H(2)O in water/tert-butyl alcohol solutions. The measurements were made at fixed temperature (293 K) as a function of tert-butyl alcohol molar fraction, x, in the range 0-0.042. The data have been compared to those of pure water in the temperature range 269-293 K. The effect of tert-butyl alcohol addition on water dynamics is equivalent to that obtained by lowering the temperature of pure water by an amount proportional to the alcohol concentration. The temperature dependence of the diffusivity parameters in pure water and their concentration dependence in tert-butyl alcohol/water solutions can be rescaled to a common curve attributing to each solution a concentration-dependent "structural temperature" lower than the actual thermodynamic one. These results can be understood in terms of Stillinger's picture of water structuring and of other more recent theoretical pictures that emphasize the influence of the geometrical properties of hydrogen bond networks on water mobility.

Abstract  Spectroelectrochemical studies on the reactivity of butanol isomers on Pt electrodes in perchloric acid medium led to the observation of structural effects that result from the different arrangements of atoms in the organic molecules. The use of differential electrochemical mass spectrometry (DEMS) to detect volatile products showed that all four isomers react on the electrode, though different product yields were observed for each compound. In spite of the differences in the electrochemical behaviour of the butanol isomers, a series of general processes accounts for the results obtained. The formation of strongly adsorbed residues by a dehydration process leading to the formation of a C=C bond was proposed for all isomers. Electroreduction of the adsorbates produces C(4) and C(3) alkanes, and the latter reveal the existence of a fragmentation process. The C(4) hydrocarbons can be formed by hydrogenation of these residues and by hydrogenolysis of alcohol molecules in the bulk solution which react at the electrode with adsorbed hydrogen. On the other hand, CO(2) is formed during electrooxidation of the adsorbed species. Partial-oxidation products containing a carbonyl group were detected from 0.2 M solutions of 1-butanol, isobutyl alcohol and sec-butyl alcohol. The tertiary alcohol tert-butyl alcohol only reacts in its adsorbed state.

Abstract  A high-resolution, high-sensitivity ac calorimeter has been developed to investigate the ''melting'' of organic and biological materials. The heart of this system is a simple yet very versatile sample cell which can be reused. High-temperature-resolution studies of the melting of n-octadecane and tert-butyl alcohol indicate interesting premelting and prefreezing phenomena in the specific heat capacity in these substances. With pure dipalmitoyl L-alpha-lecithin (DPL), in water, we obtain a very sharp (FWHM=0.38 degrees C) first-order phase transition showing no pretransition broadening or post-transition tails in the specific heat curves near the 41.2 degrees C transition point.

Abstract  We experimentally determined the density and mole fraction of CO(2) (x(CO(2))) for CO(2)-alcohol (methanol, ethanol, propanol, butanol, isopropyl alcohol, and tert-butyl alcohol) mixtures and performed molecular dynamics (MD) simulations to study the mechanisms of volume expansion at 40 °C. The volume as calculated by vapor-liquid equilibrium (VLE) data increased with decreasing alkyl chain length, although there was no effect of branched alkyl groups. Analysis of the hydrogen bond network showed that the average number of hydrogen bonds per alcohol molecule decreased with increasing branched methyl groups. At pure alcohol condition, large size hydrogen bond networks were made. With further addition of CO(2) molecules, it became difficult to contain the large hydrogen bond networks. Furthermore, the hydrogen bond networks changed to a cyclic pentamer or tetramer, and volume expansion occurred.

Abstract  Primary alcohols are acylated in good yield under almost neutral conditions with 3-acylthiazolidine-2-thiones and cesium fluoride. For secondary alcohols, the yield is improved by the addition of zinc bromide. t-Butanol is not acylated.

Abstract  Ergosterol and 7-dehydrocholesterol, common 5,7-conjugated diene sterols, react with photochemically produced singlet oxygen very efficiently to yield, in parallel pathways, the corresponding 5,8-endoperoxides and the 7 beta-hydroperoxy-5,8(9),22-trienol or -5,8(9)-dienol, respectively. The hydroperoxides decompose in an acid-catalyzed reaction to generate hydrogen peroxide and the 5,7,9(11),22-tetraenol or 5,7,9(11) trienol, respectively, with 1:1 stochiometry. The molar ratio of endoperoxide to hydroperoxide was constant (16:5) with two different reaction solvents, two different photosensitizers, and at all time points between 5 min and 3 h from the start of irradiation. Ergosterol did not react with either hydrogen peroxide or superoxide ion under our reaction conditions. Inhibition studies with nitrogen, 2,5-dimethylfuran, beta-carotene, and tert-butanol confirmed the involvement of singlet oxygen in these reactions. The unstable hydroperoxide would be expected to have undesirable biological consequences if formed in vivo.

Abstract  Surface tensions of the 1-bromobutane with isomeric butanol mixtures were measured in the temperature range 283.15 K (or 298.15 K for 2-methyl-2-propanol) to 313.15 K with a drop volume tensiometer, and the corresponding surface tension deviations were calculated. Using this information together with bulk thermodynamic properties a thermodynamic study on surface formation was presented. This study includes the calculation of excess surface compositions and excess properties of surface formation.

Abstract  Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time.

Abstract  Multi-path variational transition state theory (MP-VTST) provides a conformationally complete framework for calculating gas-phase rate constants. For reactions in which the transition state has distinguishable torsional minima (which include most reactions), there are multiple possible reaction paths. In principle MP-VTST includes the contributions from all the reaction paths, and it should explicitly treat the variational and tunneling effects of each path, but in practice one may need to truncate the number of paths included in MP-VTST calculations in order to achieve a balance between computational cost and accuracy. In this work, we present calculations including all paths for two prototype combustion reactions, namely the two hydrogen abstraction reactions from tert-butanol by HO2 radical. For both reactions we included all the reaction paths. Since abstraction at C has 46 paths, it provided a good opportunity to carry out a case study in which we investigated the errors introduced by truncating the number of paths. For the reaction studied, we found that the variational and multidimensional tunneling transmission coefficients are very different for different reaction paths, which provides new evidence that MP-VTST is necessary for treating path-dependent variational effects and multidimensional tunneling. We found that tunneling transmission coefficients can be much larger for higher-energy paths than for lower-energy ones. Interestingly, the simple hypothesis that higher barriers are narrower does not explain this finding in the present case; we found instead that the effect is due to higher-energy barriers having the possibility of tunneling at energies farther below the barrier top. We also show that a previously applied criterion for judging convergence with respect to the number of paths may not be reliable at low temperature.

Abstract  To investigate the influence of bulky alkyl groups on hydrogen-bonded (H-bonded) network structures of alcohols, infrared (IR) spectra of protonated clusters of 2-propanol (2-PrOH) and tert-butyl alcohol (t-BuOH) were observed in the OH and CH stretch regions. In addition, by varying the tag species, the temperature dependence profile of the isomer population of H+(t-BuOH)n was revealed. An extensive search for stable isomers was performed using dispersion-corrected density functional theory methods, and temperature-dependent IR spectral simulations were done on the basis of the harmonic superposition approximation. The computational results qualitatively agreed with the observed size and temperature dependence of the H-bonded network structures of these protonated bulky alcohol clusters. However, the difficulty in the quantitative evaluation of dispersion was also demonstrated. It was shown that H+(2-PrOH)n (n = 4-7) have essentially the same network structures as the protonated normal alcohol clusters studied so far. On the other hand, H+(t-BuOH)n (n = 4-8) showed a clear preference for the smaller-membered ring structures, that is very different from the preference of the protonated normal alcohol clusters. The origin of the different structure preferences was discussed in terms of the steric effect and dispersion.

Abstract  Alcohols such as ethanol (EtOH) and tert-butanol (TBA) are frequently used as quenching agents to identify the primary radical species in the persulfate (PS)-based oxidation processes. However, the contribution of alcohol radicals (ARs) to contaminant degradation in this process has rarely been assessed. In this study, trichloroacetic acid (TCA), phenol, and carbon tetrachloride were selected as probes to test the role of ARs in the thermally activated PS system. It was found that the degradation rates of these compounds were largely depended on their reactivities with ARs and the concentration of dissolved oxygen in the reaction system. In the PS/alcohol system, TCA was degraded efficiently under anaerobic conditions, while it was hardly degraded in the presence of oxygen. The results of electron paramagnetic resonance, reducing radical quenching studies, and the analysis of PS consumption suggested that ARs were the dominant reactive species contributing to TCA degradation in the PS/EtOH system under anaerobic conditions. Further studies indicated that ARs could significantly degrade CCl4 through dechlorination but not phenol. CCl4 was also degraded efficiently by ARs when oxygen in the reaction solution was completely consumed by ARs. This study highlights the important role of alcohol radicals in the degradation of contaminants during quenching studies in PS-activated processes.

Abstract  The formation of Cr2O3 nanopartides by gamma-irradiation of dichromate solutions was investigated in the presence of radical scavengers, tert-butyl alcohol, nitrous oxide, and dissolved oxygen. The concentrations of Cr-VI and Cr-III species and the chemical composition and sizes of particles that were formed were measured as a function of irradiation time. A mechanism is proposed that is consistent with the observed effects of scavengers on the kinetics of reduction of Cr-VI in solution to solid Cr-III and the final size of Cr2O3 nanopartides that are formed. The chromium reduction occurs in three stages: Stage I involves homogeneous aqueous reduction of Cr-VI(aq) to Cr-III(aq) followed by spontaneous condensation of Cr(OH)(3), providing nucleation sites onto which Cr-VI and Cr-III coprecipitate and form mixed Cr-VI/Cr-III oxide/hydroxide particles. In Stage II, the aqueous reduction of Cr-VI(aq) and Cr-III(aq) reaches steady state but the adsorption of Cr-VI continues, growing the mixed Cr-VI/Cr-III oxide/hydroxide particles. Stage 3 involves the solid-state conversion of Cr-VI and Cr-III, and the particles slowly convert from a mixed Cr-VI/Cr-III oxide/hydroxide to Cr(OH)(3) and then to Cr2O3. Adding a radical scavenger in solution affects the kinetics of particle formation and growth at different stages differently. This information can be used to tailor the final sizes of particles.

Abstract  Enzymatic transesterification of rapeseed oil with methanol has been carried out in a batch process. Methyl ester is produced in the course of enzymatic reaction. The product is used as biofuel in diesel engine without any further post treatment. There is no serious emission of hazardous particulate matter, since raw material does not contain any impurities such sulfur dioxide. The reaction is carried out under various conditions and the desire operating parameters were determined. In this work the effects of enzyme concentration, methanol to oil molar ratio, water content, type of solvent, volumetric ratio of t-butanol and reaction temperature have been investigated. Maximum methyl ester conversion of 70.32% is obtained for enzyme 6% (w/w of Oil), water 5% (v/v of oil) and methanol to oil ratio of 9:1 at 37 degrees C for 72 h. In order to identify a suitable condition for biodiesel production, different solvents have been used. The highest methyl ester conversion is observed with t-butanol as moderate polar solvent.

Abstract  A method to assess the ability of a photocatalyst to induce reactions with free or trapped hydroxyl radicals versus direct charge-transfer processes is here proposed, based on the use of phenol and 2-hydroxybenzoic acid (salicylic acid) as test substrates. The rationale is that phenol degradation would be preferentially (although not exclusively) induced by hydroxyl radicals, while salicylic acid would mainly undergo direct charge-transfer oxidation. The use of t-butanol as selective. (OH)-O-center dot scavenger is helpful to understand how much each substrate is a selective indicator of the intended reaction pathway in the presence of a given semiconductor oxide. Phenol and salicylic acid should be used at low concentration (e.g. 25 mu mol L-1) to limit the occurrence of the back-reactions, the importance of which can be highlighted by using higher initial concentration values (e.g. l mmol L-1). The method was optimized with the well-studied photocatalysts Evonik P25 and Wackherr's "Oxyde de titane standard", and it was then applied to study the behavior of two TiO2/Al2O3 binary oxide systems (where TiO2 occurs as a mixture of anatase and rutile). The latter photocatalysts were poorly efficient toward the degradation of phenol, but they performed better with salicylic acid. These findings, which are coherent with the results of t-butanol addition, suggest that the two binary oxide systems would induce charge-transfer rather than. OH reactions.

Abstract  Reaction of the bulky bi-phenols 2,2'-RCH[4,6-(t-Bu)(2) C6H2OH](2) (R = Me (LH2)-H-1Me, Ph (LH2)-H-1Ph) with the bis (imido) molybdenum (VI) tert- butoxides [Mo (NR1) (NR2) (Ot-Bu)(2)] (R-1 = R-2 = 2,6-C6H3-i-Pr-2; R-1 = t-Bu, R-2 = C6F5) afforded, following the successive removal of tert-butanol, the complexes [Mo (NC(6)H(3)i-Pr-2- 2,6)(2)L-1Me] (1), [Mo(NC(6)H(3)i-Pr-2-2,6)(2)L-1Ph] (2) and [Mo (Nt-Bu)(mu-NC6F5)(L-1Me)](2) (3). Similar use of the tri-phenol 2,6-bis (3,5-di-tert-butyl-2-hydroxybenzyl)-4-methylphenol ((LH3)-H-2) with [Mo(NC(6)H(3)i-Pr-2-2,6)(2) (Ot-Bu)(2)] afforded the oxo-bridged product [Mo(NC (6)H(3)i-Pr-2-2,6)(NCMe)(mu-O)(LH)-H-2](2) (4), whilst use of the tetra-phenols alpha,alpha,alpha',alpha'-tetrakis (3,5-di-tert-butyl-2-hydroxyphenyl)-p-or -m-xylene (LH4)-H- 3p/(LH4)-H-3m led to {[Mo (NC(6)H(3)i-Pr-2-2,6)(2)](2)(mu-L-3p)} (5) or {[Mo(NC(6)H(3)i-Pr-2- 2,6)(2)](2)(mu-L-3m)} (6), respectively. Similar use of [Mo(NC6F5)(2)(Ot-Bu)(2)] with (LH4)-H-3p afforded, after work-up, the complex {[Mo(NC6F5)(Ot-Bu)(2)](2)(mu-L-3p)}center dot 6MeCN (7.6MeCN). Molecular structures of 1, 2 center dot CH2Cl2, 3, 4 center dot 6MeCN, 6 center dot 2C(6)H(14), and 7 center dot 6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP) epsilon-caprolactone; for comparative studies the precursor complex [Mo(NC(6)H(3)i-Pr-2-2,6)(2)Cl-2(DME)] (DME = 1,2-dimethoxyethane) has also been screened. Results revealed that good activity is only achievable at temperatures of >= 100 degrees C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (M- n) were much lower than calculated values.

Abstract  In this paper we present a standardized protocol for the complete evaluation of greenness of 18 industrial routes to methyl methacrylate (MMA) covering material and energy consumptions and environmental and safety impacts. A methodology for estimating energy consumption for chemical reactions and synthesis plans from published journal and patent literature procedures is fully described. A new energy metric pertaining to enthalpic changes from standard state conditions (298 K, 1 atm) to reaction conditions (T-rxn, p(rxn)) for all input materials used in a synthesis plan for the production of 1 mol of product is defined with respect to the heating and evaporation of 1 mol of water from 298 K and 1 atm. Limitations and best practices of running the protocol are discussed. The present study serves as a template for implementing the protocol to the green metrics analysis of high volume industrial chemicals. Results of plan rankings are compared with previous work on inherent safety indexes. Based on these findings, the isobutylene alcohol routes to MMA are found to have the overall greenest attributes among the 18 routes examined. and t-butyl alcohol routes to MMA are found to have the overall greenest attributes among the 18 routes examined.

Abstract  This study reports results of experiments on the isolated droplet burning characteristics of butanol isomers (n-, iso-, sec-, and tert-) under standard atmosphere conditions in an environment that promotes spherical combustion. The data are compared with predictions from a detailed numerical model (DNM) that incorporates complex combustion chemistry, radiative heat transfer, temperature dependent variable fluid properties, and unsteady gas and liquid transport. Computational predictions are generated using the high temperature kinetic models of Sarathy et al. (2012) and Merchant et al. (2013). The experiments were performed in a free-fall facility to reduce the effects of buoyancy and produce spherical droplet flames. Motion of single droplets with diameters ranged from 0.52 mm to 0.56 mm was eliminated by tethering them to two small-diameter SiC filaments (similar to 14 mu m diameter). In all the experiments, minimal sooting was observed, offering the opportunity for direct comparison of the experimental measurements with DNM predictions that neglect soot kinetics. The experimental data showed that the burning rates of iso- and sec-butanol are very close to that of n-butanol, differing only in flame structure. The flame stand-off ratios (FSR) for n-butanol flames are smaller than those for the isomers, while tert-butanol flames exhibited the largest FSR. DNM predictions based upon the kinetic model of Sarathy et al. over-predict the droplet burning rates and FSRs of all the isomers except n-butanol. Predictions using a kinetic model based upon the work of Merchant et al. agree much better with the experimental data, though relatively higher discrepancies are evident for tert-butanol simulation results. Further analyses of the predictions using the two kinetic models and their differences are discussed. It is found that the disparity in transport coefficients for isomer specific species for Sarathy et al. model fosters deviation in computational predictions against these newly acquired droplet combustion data presented in this study. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Abstract  A series of dimeric amino alcohol derived Schiff bases with various chiral amino alcohols and their corresponding bimetallic titanium complex were generated in situ. Thereafter with the in situ generated complexes, the asymmetric oxidation of prochiral aryl alkyl sulfides has been investigated using aqueous H2O2 as a terminal oxidant. During the study we found that the use of methanol or tert-butanol as an additive improved the catalytic activity in terms of both conversion and enantioselectivity. Moreover we observed a co-operative effect of the two reactive units of the bimetallic complex, which results in high reactivity as well as enantioselectivity compared to the corresponding monomeric complex. With this improved catalytic system several aryl alkyl sulfides and 1,3-dithianes were oxidised to the corresponding sulfoxides with good to high enantioselectivity (ee 78-99%) and conversion (70-99%). Unlike the monomer, oxidation of substrates like benzyl phenyl sulfide was achieved with high enantioselectivity as well as high yield.

Abstract  Partial glycerides such as monoacylglycerides (MAGs) are important functional ingredients with various applications in the cosmetics and food industry. Direct synthesis of high purity MAGs is commercially not feasible due to low selectivity and substrate miscibility problems. In this article, a selectivity increase in synthesis towards MAG with the addition of 5 wt% of the amphoteric surfactant cocamidopropyl betaine (CAPB) compared to a solvent free reaction is demonstrated. In comparison to tert-butanol, the addition of CAPB leads to similar MAG contents in the equilibrium state and furthermore CAPB does not need to be removed from the reaction, because it is an approved additive in cosmetic products. Additionally it acts as a solubilizer in the product mixture. By adding 5 wt% of CAPB to the enzymatic glycerolysis of TL, the selectivity towards ML could be increased by 17% compared to the solvent free reaction. Also in the enzymatic esterification of glycerol and lauric acid the addition of 5 wt% CAPB shows an increase in selectivity towards ML up to 9% compared to the solvent free esterification. The major function is a direct influence on the phase behavior of the reaction mixture.

Abstract  We present densities of pure 2-butanol and tert-butanol from 283.15 to 363.15 K and 303.15 to 363.15 K at pressures up to 66 MPa. We have measured the densities using a vibrating tube densimeter, and the calibration of the apparatus uses the forced path calibration method (FPMC). This calibration method depends upon the mechanical properties of the cell and allows us to have a standard uncertainty in the density less than 0.0004 g/cm(3). The new experimental densities of agree within 0.1% with densities in the literature.

Abstract  M/TiO2 photocatalyst activity for H-2 production depends on both the metal co-catalyst (M) and the reaction medium. To quantify such effects, we compared the performance of M/TiO2 photocatalysts (M = Pd, Pt, Au) for H-2 production in different alcohol-water mixtures under UV excitation. Photocatalysts were prepared using Degussa P25 TiO2 at metal loadings of 0.5 and 1 wt.% for Pd, 1 wt.% for Pt and 1 wt.% for Au. TEM, UV-Vis, XPS and EXAFS analyses confirmed the presence of supported metal nanoparticles of size similar to 2, 1.3 and 5.4 nm for Pd/TiO2, Pt/TiO2 and Au/TiO2, respectively. Photoluminescence data established that the metal co-catalysts effectively suppressed electron-hole pair recombination in TiO2 following photo-excitation. The activities of the M/TiO2 photocatalysts for Hy production were evaluated in a wide range of alcohol-water mixtures (alcohol concentration 10 vol.%) under UV (365 nm, 5 mW cm(-2)). H-2 production rates in the alcohol-water mixtures were dependent on (i) the metal co-catalyst; (ii) the co-catalyst loading; and (iii) the alcohol type. Co-catalyst activity followed the order Pd > Pt approximate to Au. The highest Hy production rates were achieved for the 1 wt.% Pd/TiO2 photocatalyst in glycerol-water mixtures (47.5 mmol g(-1)h(-1)) and 1,2-ethanediol-water mixtures (44.5 mmol g(-1) h(-1)). H2 production rates decreased in the order glycerol > 1,2-ethanediol > 1,2-propanediol > methanol > ethanol > 2-propanol > tert-butanol >> water. For each M/TiO2 photocatalyst, correlations were established between the rate of H2 production and specific alcohol properties, especially alcohol polarity and the exponential of the alcohol oxidation potential. (C) 2015 Elsevier Inc. All rights reserved.