Primary Alcohol Groups Research Articles

Identification of the degradation pathways of alkanolamines with TiO 2 photocatalysis

The present study deals with the photocatalytic degradation of the alkanolamine, 2-dimethylamino-2-methyl-1-propanol (DMAMP), in the presence of TiO 2 particles and UV-A ( λ = 365 nm) radiation. The obtained results show complete oxidation of DMAMP after 20 h, and a little over 90% of DMAMP was mineralization after 64-h of treatment. The effects of the solution pH, catalyst loading, and anions on the photocatalytic degradation of DMAMP were investigated, as well as the reaction intermediates that were formed during treatment. To the best of our knowledge, this is the first time that reports the degradation pathways of DMAMP. A number of intermediates were identified by GC/MS techniques during the treatment of DMAMP, following three tentative degradation routes. The first one is based on the oxidation of the primary alcohol group leading to the formation of corresponding aldehyde and carboxylic acid. The second route is based on the rupture of the N–C bond to form 2-methylpropanal and acetone. The last degradation route is based on the cyclization of the β-amino alcohol group to form the oxazolidine derivatives.

Effect of fermentation conditions on the production and characteristics of cellulose pellicles from Acetobacter xylinum

Two different homogenous reactions on bacterial cellulose (BC), kenaf fiber (KF) and microcrystalline cellulose (MC) were performed to monitor their chemical reactivity. The first reaction was selective oxidation of the primary hydroxyl group with sodium chlorite in the presence of catalytic amount of sodium chloride. While, the second was the formation of triester hypoiodous cellulose using potassium iodate and potassium iodide. The chemical structures of these derivatives were investigated using FT-IR and solid state 13C NMR spectroscopies. The BC fibrils required the shortest time among these cellulose samples for both reactions, whereas the viscosity values of BC after iodination and oxidation have the best values compared to KF and MC. FT-IR results show the absence of the hydroxy group of BC and a weak absorption band in both KF and MC. On the other hand, the crystallinity index (CI) of BC is higher than those of both KF and MC. FT-IR spectra of the oxidized different cellulose samples, confirmed the presence of a strong absorption band at around 1590 cm−1 that attributed to vibration band of carbonyl group of carboxylic moiety. Moreover, in the 13C NMR spectrum of oxidized cellulose, the lack of signal at 62 ppm and the appearance of signal at 171 ppm indicated that the primary alcohol group is completely oxidized to carboxylic acid. These results showed that BC had a higher reactivity than other samples due to its great purity and low degree of polymerization.

Heteropoly acid-based supported ionic liquid-phase catalyst for the selective oxidation of alcohols

A supported ionic liquid strategy has been applied for the immobilization of a heteropolyacid, molybdovanadophosphoric acid, onto ionic liquid-modified mesoporous silica SBA-15. The immobilized catalyst demonstrated high activity in the aerobic oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. No overoxidation of the primary alcohols to carboxylic acids was observed. Secondary alcohols were chemoselectively oxidized to ketones in the presence of primary alcohol, hetero atom, and allyl groups. This catalyst could be recycled five times without obvious loss of activity.

Formation and structure elucidation of N-(2,3,4-tri- O-acetyl-β- d-glucopyranosyl)- N′-acetylthiourea

Treatment with concd HCl/MeOH transformed N-(tetra- O-acetyl-β- d-glucopyranosyl)- N′-acetylthiourea, via selective cleavage of the primary alcoholic ester group, into the title compound.

Photochemistry of Imidacloprid in Model Systems

The photochemical behavior of the neonicotinoid insecticide imidacloprid was studied with regard to different chemical environments. Different model solvents simulated the structure moieties mainly occurring in waxes and cutin of the plant cuticle. Cyclohexane and cyclohexene substituted saturated and unsaturated hydrocarbon chains, whereas ethanol and 2-propanol were models for primary and secondary alcohol groups of cuticular components. After 5 h of irradiation, imidacloprid was completely degraded in all solvents. With 88-96 mol% 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine was formed as the main product, whereas 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-one was identified as minor product in the range 4-6 mol%. By contrast, besides the photoproducts formed in organic solvents, irradiation of the solid imidacloprid on a glass surface delivered a complex variety of unidentified photoproducts. The nucleophilic addition reaction of the main photoproduct, 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine, with both cyclohexene oxide and methyl 9,10-epoxystearate as model compounds indicates that epoxidized cutin acids are possible reaction partners for the formation of plant cuticle bound residues of imidacloprid, which could explain the reported findings of nonextractable residues of imidacloprid in plants.

Efficient loading of primary alcohols onto a solid phase using a trityl bromide linker

The Letter describes an improved, rapid and mild strategy for the loading of primary alcohols onto a polystyrene trityl resin via a highly reactive trityl bromide linker. This protocol facilitates an efficient resin loading even of acid-sensitive or heat-labile alcohols, which otherwise require expensive or non-commercial resin types. Secondary alcohols were only attached in moderate to low yields, while attempts to load a tertiary alcohol expectedly failed. Importantly, selective attachment of diols via a primary alcohol group in the presence of more hindered alcohol groups proved possible. The effects of activation time and reagent excess as well as alcohol structure were investigated. This improved method provides a convenient access to O-linked resin-bound N-Fmoc-protected amino alcohols that may be employed in SPS of peptides with C-terminal alcohol functionalities. In the case of a sensitive alcohol containing an activated aziridine functionality, the use of the trityl bromide linker proved superior to a recently described silver triflate-assisted trityl chloride resin-based procedure.

Homogenous reactions of cellulose from different natural sources

Two different homogenous reactions on bacterial cellulose (BC), kenaf fiber (KF) and microcrystalline cellulose (MC) were performed to monitor their chemical reactivity. The first reaction was selective oxidation of the primary hydroxyl group with sodium chlorite in the presence of catalytic amount of sodium chloride. While, the second was the formation of triester hypoiodous cellulose using potassium iodate and potassium iodide. The chemical structures of these derivatives were investigated using FT-IR and solid state 13C NMR spectroscopies. The BC fibrils required the shortest time among these cellulose samples for both reactions, whereas the viscosity values of BC after iodination and oxidation have the best values compared to KF and MC. FT-IR results show the absence of the hydroxy group of BC and a weak absorption band in both KF and MC. On the other hand, the crystallinity index (CI) of BC is higher than those of both KF and MC. FT-IR spectra of the oxidized different cellulose samples, confirmed the presence of a strong absorption band at around 1590 cm −1 that attributed to vibration band of carbonyl group of carboxylic moiety. Moreover, in the 13C NMR spectrum of oxidized cellulose, the lack of signal at 62 ppm and the appearance of signal at 171 ppm indicated that the primary alcohol group is completely oxidized to carboxylic acid. These results showed that BC had a higher reactivity than other samples due to its great purity and low degree of polymerization.

Physicochemical Properties of Partially Oxidized Corn Starch from Bromide‐Free TEMPO‐Mediated Reaction

This study was conducted to determine the optimal temperature and time for the regiospecific oxidation of primary alcohol groups in corn starch with 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion (TEMPO) and sodium hyphochlorite (NaOCl). The study also elucidated the molecular structure of fully oxidized corn starch (FOCS) prepared at optimum temperature and physicochemical properties of the partially (10%, 20%, and 30%) oxidized corn starches (POCS). The reaction time rapidly decreased up to 30 degrees C, and then gradually decreased. Selectivity, yield, and viscosity were drastically reduced at temperatures higher than 35 to 40 degrees C. Optimal oxidation temperature for the production of FOCS was determined as 35 degrees C. Regiospecific oxidation of the primary alcohol group without oxidation of the secondary alcohol group was confirmed in (13)C-NMR and IR spectra. Water-binding capacity, swelling power, solubility power, and transmittance of POCS increased as the degree of oxidation increased. Hardness, gumminess, and chewiness of corn starch gel containing POCS were not significantly different from those of native corn starch gel at 1-d storage, but the values of the starch gel containing POCS were smaller than those of the native starch gel after 1-d storage. However, springiness and cohesiveness did not differ significantly among the samples regardless of storage time.

Caractérisation physicochimique du dérivé amphiphile per(6-déoxy) de la bêta-cyclodextrine (B6) et étude de son activité hémolytique et de son action vis-à-vis des membranes

Natural beta-cyclodextrin bears an internal crown consisting of six primary alcohol groups. Their removal leads to per(6-deoxy)beta-cyclodextrin (B6). The physicochemical properties of B6 and its interactions with membranes were investigated to give an evaluation of haemolytic activity and complexing properties of this chemical species. This was achieved by using surface tension and haemolytic activity (i.e.DH50 determination, the concentration inducing 50% haemolysis) measurements,1H-31P-NMR and EPR spectroscopies. Whereas B6 solubility in the water is close to that of natural beta CD (about 5 g/L at 20 degrees C) and exhibits amphiphilic properties greater than those of beta CD (log P: -1.36 at 300 K), B6 forms micelles in aqueous solution of 20 molecules, even at low concentration 0.8mM. In addition, B6 exhibits tensioactive properties leading to solubilization and even, in some cases orientation of synthetic membranes. Although no complex formation with membrane components was observed, NMR and ESR showed interactions with the surface of the membrane. Subsequently, B6 exhibits an important haemolytic activity, whose mechanism, different from that of beta CD, is discussed.

Synthesis of rutinosides and rutinose by reverse hydrolysis catalyzed by fungal α-l-rhamnosidases

The synthesis of α-l-rhamnosyl(1→6)-β-d-glucosides (rutinosides) and α-l-rhamnosyl(1→6)-β-d-glucose (rutinose) catalyzed by several fungal α-l-rhamnosidases was studied by the reverse hydrolysis reaction between rhamnose plus naringenin 7-β-d-glucoside (prunin) and rhamnose plus glucose, respectively. The products of the reaction were determined by HPLC with some available standards. As expected, the major product of prunin rhamnosylation was always narirutin (naringenin-7-β-d-rutinoside), which originated from the glycosylation of the primary alcoholic group of the glucoside. Whereas, Aspergillus terreus, Penicillium decumbens and P. ulaiense α-l-rhamnosidases gave other minor derivatives besides narirutin, two commercial A. niger enzymes synthesized it as the unique reaction product. Initial rate kinetics of narirutin synthesis catalyzed by the purified A. niger α-l-rhamnosidase did not permit distinction between sequential and ping pong mechanisms, but showed strong inhibition by the substrate l-rhamnose. Equations derived for competitive inhibition together with non-exclusive inhibition by this substrate, gave the best fit to the kinetic experimental data. When glucose was rhamnosylated by the A. niger enzyme, two other minor products appeared together with the disaccharide rutinose. Conditions for obtaining maximum rutinose yield were determined.

Soil bacterium Pseudomonas sp.: destroyer of mustard gas hydrolysis products

A bacterial culture capable of utilizing products of mustard gas hydrolysis as a source of carbon was isolated from soil. This culture was tolerant to organochlorine substances in the hydrolysate. The bacterium was identified as Pseudomonas sp. The bacterium utilizes the major product of mustard gas hydrolysis, thiodiglycol, through two pathways. One involves the oxidation of the primary alcoholic groups in thiodiglycol, yielding thiodiglycolic and thioglycolic acids. The cleavage of the C-S bonds in these acids gives rise to acetate, which is then used further in the cell metabolism. The other pathway involves the cleavage of the C-S bond in the thiodiglycol molecule, yielding beta-mercaptoethanol, which is transformed by Pseudomonas sp. into thioglycolic acid. The results show the promise of this bacterium for the bioremediation of mustard gas-contaminated soils.

Physicochemical Properties of Cellulose Selectively Oxidized with the 2,2,6,6‐Tetramethyl‐1‐Piperidinyl Oxoammonium Ion

This study examined the characteristics of the oxidation reaction on the primary alcohol groups in cellulose involving the 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion (TEMPO) and determined the optimum conditions for the preparation of oxidized cellulose (OC). The applicability of OC in polysaccharide systems was also investigated. The effects of TEMPO, sodium bromide (NaBr), and temperature on the oxidation reaction time, yield, and selectivity for primary alcohol groups were examined using response surface methodology (RSM). The reaction time decreased with increases in the temperature and the levels of TEMPO and NaBr. The yield increased with the level of NaBr and decreased as the temperature increased. Selectivity increased with the temperature and decreased as the levels of TEMPO and NaBr increased. The optimum levels of TEMPO and NaBr and the optimum temperature for the production of OC were determined as 0.3 mM/100 mM anhydroglucose unit (AGU), 50 mM/100 mM AGU, and 25 degrees C, respectively. The water and oil binding capacity and viscosity of cellulose increased with oxidation. Wheat starch containing OC exhibited a decreased initial pasting temperature and setback, but increased peak viscosity, gelatinization, and retrogradation enthalpy (DeltaH). The hardness of the wheat starch gel decreased significantly upon the addition of OC.

Supramolecular Structure of Self-assembled Synthetic Zinc-131-oxo-chlorins Possessing a Primary, Secondary or Tertiary Alcoholic 31-Hydroxyl Group: Visible Spectroscopic and Molecular Modeling Studies¶

Supramolecular Structure of Self-assembled Synthetic Zinc-131-oxo-chlorins Possessing a Primary, Secondary or Tertiary Alcoholic 31-Hydroxyl Group: Visible Spectroscopic and Molecular Modeling Studies¶

A synthesis of a common intermediate to the lactone–pyrrolidinone ring systems in oxazolomycin A and neooxazolomycin

A 5- exo-dig radical cyclisation of the bromoamide 34 derived from the enantiopure α-ethynyl substituted amino alcohol 31 led to a 2:1 mixture of β-C3 and α-C3 methyl epimers of the pyrrolidinone 35a– 36a in a combined yield of 73%. Treatment of the homoallylic alcohol 35b, derived from 35a, with OsO 4–TMEDA, gave a single diastereoisomer of the pyrrolidinone triol 37, resulting from selective dihydroxylation from the β-face, i.e. syn to the CH 2OH group of 35b. The pyrrolidinone triol 37 is a potential common precursor, cf. 9, to the spiro β-lactone pyrrolidinone 8 and the γ-lactone pyrrolidinone 10 ring systems in oxazolomycin A ( 1) and neooxazolomycin 2, respectively. Sequential protection of the 1,2-diol functionality in 37 as the acetonide 39, and the primary alcohol group in 39 as the SEM ether 41a, followed by methylation of the nitrogen centre in 41a, using NaH–MeI, then gave the selectively protected pyrrolidinone 42.

Controlling the degree of esterification in lipase catalysed synthesis of xylitol fatty acid esters

Xylitol fatty acid esters of increasing chain length were synthesised from xylitol and free fatty acids in binary mixtures of tert-butanol ( t-BuOH) and pyridine using Candida antarctica lipase B as biocatalyst. NMR and GC analyses revealed that monoesters of all acyl donors were primarily substituted at the C-1 position (93–97%, mol/mol) and to a minor extent at the C-2 position introducing asymmetry to the structure; while acylation at C-3 was not found. Diesters were esterified mainly at the C-1 and C-5 positions (87–100%, mol/mol) and to a minor extent 1,2-di- O-acyl- and 1,4 -di- O-acyl xylitol esters were identified. Acylation of the secondary alcohol groups was interpreted as a result of acyl migration, because it occurred at a later stage of the process at a significantly lower rate than acylation of the primary alcohol groups and because it decreased with increasing chain length of the acyl donor. For acyl donors of chain lengths higher than four, the degree of esterification was controlled by the pyridine content of the reaction medium with the highest yield of monoesters obtained in 55% (v/v) pyridine. With butanoic acid the highest yield of monoester was obtained in pure t-BuOH. Under these conditions a degree of conversion of 26–41% of xylitol – and a yield of 22–29% monoester was obtained already after 4.5 h of incubation at 45 °C. The initial reaction rate for monoester synthesis was 5–19 times higher than for diester synthesis correlating inversely with the chain length of the acyl donor. At an acyl acceptor to donor ratio of 1:5 (mol/mol) the highest initial reaction rate of monoester synthesis was observed with hexanoic acid.

Oxidation of mono- and polyalcohols with gold: Comparison of carbon and ceria supported catalysts

Aim of this work is the investigation of the gold catalysed liquid-phase oxidation of polyalcohols with both, primary and secondary alcohol groups, in order to evaluate the potential of gold catalysts to oxidise a secondary alcohol group in presence of a primary group. For that purpose we investigated the heterogeneously catalysed liquid-phase oxidations of n-propanol, as reference for the oxidation of the primary alcohol group only, of propylene glycol, where the competitive reaction can be examined and finally of glycerol, which is the target reaction due to known economic aspects. We report on the performance of ceria supported gold catalysts in these reactions and discuss the results in dependency of the specific surface area of the support, the catalyst and support preparation method and the catalyst activation conditions. Finally, in order to estimate the relative activity and selectivity of the ceria supported catalysts we compared the catalytic results with the performance of carbon and titania supported gold catalysts.

Adsorption of Cd2+ and Cu2+ by Oxidized Cellulose from TEMPO‐mediated Selective Oxidation of Alkaline Natural Cellulose Pulp

In the present work, oxidized celluloses were prepared by the 2,2,6,6‐Tetramethyl pipedine‐1‐oxyl radical (TEMPO)‐mediated selective oxidation of the primary alcohol groups at C6 position from natural cellulose pulps treated with NaOH solution. Their adsorption properties for Cu2+ and Cd2+ in aqueous salt solutions were investigated. The results showed that the greater the carboxyl content and degree of substitution, the higher the value of the adsorption capacity. However, since the oxidized cellulose prepared from cellulose treated with 25% NaOH solution, having carboxyl content 14.98%, was partially soluble in aqueous solutions, the dissolution of this sample resulted in reduced metal‐adsorption efficiency. The metal‐adsorption of the oxidized celluloses followed the Langmuir adsorption isotherm. Compared with the oxidized cellulose having carboxyl content 5.12% from cellulose treated with 15% NaOH solution, the oxidized cellulose having carboxyl content 5.12% from cellulose treated with 25% NaOH solution has much stronger metal‐adsorption capacity.

An investigation of the pyranose ring interconversion path of α- l-idose calculated using density functional theory

The interconversion pathways of the pyranose ring conformation of α- l-idose from a 4 C 1 chair to other conformations were investigated using density functional calculations. From these calculations, four different ring interconversion paths and their transition state structures from the 4 C 1 chair to other conformations, such as B 3,O, and 1 S 3, were obtained. These four transition-state conformations cover four possible combinations of the network patterns of the hydroxyl group hydrogen bonds (clockwise and counterclockwise) and the conformations of the primary alcohol group ( tg and gg). The optimized conformations, transition states, and their intrinsic reaction coordinates (IRC) were all calculated at the B3LYP/6-31G ∗∗ level. The energy differences among the structures obtained were evaluated at the B3LYP/6-311++G ∗∗ level. The optimized conformations indicate that the conformers of 4 C 1, 2 S O, and B 3,O have similar energies, while 1 S 3 has a higher energy than the others. The comparison of the four transition states and their ring interconversion paths, which were confirmed using the IRC calculation, suggests that the most plausible ring interconversion of the α- l-idopyranose ring occurs between 4 C 1 and B 3,O through the E 3 envelope, which involves a 5.21 kcal/mol energy barrier.

STRUCTURAL DETERMINATION AND CHEMICAL MODIFICATIONS OF THE POLYSACCHARIDE FROM SEEDS OF Prosopis chilensis Mol. (Stuntz)

The polysaccharide extracted from Prosopis chilensis seeds in acidic medium showed by total hydrolysis and gas-liquid chromatography analysis of the alditol acetates to be composed of galactose and mannose in the molar ratio 1.0:1.9. Studies by methylation and 1H and13C NMR spectroscopy indicated that the polysaccharide was a galactomannan with a chain of D-mannopyranosyl residues linked b 1 4 which carried alternatively a-D-galactopyranosyl residues at position O-6 of D-mannose units. The chemical modification of the galactomannan by reaction with sodium chloroacetate afforded in 95.3% yield, a derivative which gave a very viscous solution with water. By titration it was determined a carboxymethylation degree of 0.42 indicating that 64% of the alcoholic groups were etherified. Reaction of the galactomannan with TEMPO-NaCl-NaOBr system gave a water soluble polysaccharide. The DEPT 135o NMR spectrum indicated that the primary alcoholic groups of galactopyranosyl and unbranched mannopyranosyl residues were fully oxidised

Wrong gas/liquid partition data by gas chromatography

In a paper published in 1992 [K.S. Reddy, J.-Cl. Dutoit, E.sz. Kováts, Pair-wise interactions by gas chromatography. I. Interaction free enthalpies of solutes with non-associated primary alcohol groups, J. Chromatogr. 609 (1992) 229] retention indices and standard chemical potential differences (SPOT-s) are given for about 160 solutes on a liquid branched paraffin hydrocarbon of the carbon number, z = 78. For the temperature dependence of the SPOT-s the proposal of Kirchhoff was accepted i.e. that at higher temperatures the molar heat capacity difference of the solute between the gas phase and the solution is nearly constant in a broad temperature range. The data were determined under conditions where the effect of adsorption could be neglected. By comparing the published data with those determined on another branched paraffin of the carbon number, z = 87 [F. Riedo, D. Fritz, G. Tarján, E.sz. Kováts, A tailor-made C87 hydrocarbon as a possible non-polar standard stationary phase for gas chromatography, J. Chromatogr. 126 (1976) 63] it is shown that the reported thermodynamic constants of solutes determined experimentally at higher temperatures (the group “H”) are wrong on C78. In the present paper, the method of correction and the resulting corrected data are given. In later papers retention data are given on eight polar derivatives of the hydrocarbon C78 relative to those measured on the nonpolar standard [R. Cloux, G. Défayes, K. Fóti, J.-Cl. Dutoit, E.sz. Kováts, Pair-wise interactions by gas chromatography. III. Synthesis of isosteric stationary phases for gas chromatography, Synthesis (1993) 909; G. Défayes, K.S. Reddy, A. Dallos, E.sz. Kováts, Pair-wise interactions by gas chromatography. V. Interaction free enthalpies of solutes with primary chloro- and bromo-alkanes, J. Chromatogr. A 699 (1995) 131; K.S. Reddy, E.sz. Kováts, Pair-wise interactions by gas chromatography. II. Sociation free enthalpies of some hydrogen bonding solutes with non-associated primary alcohol groups, Chromatographia 34 (1992) 249; K.S. Reddy, R. Cloux, E.sz. Kováts, Pair-wise interactions by gas chromatography. IV. Interaction free enthalpies of solutes with trifluoromethyl-substituted alkanes, J. Chromatogr. A 673 (1994) 181; K.S. Reddy, R. Cloux, E.sz. Kováts, Pair-wise interactions by gas chromatography. VI. Interaction free enthalpies of solutes with primary methoxyalkane, cyanoalkane and alkanethiol groups, J. Chromatogr. A 704 (1995) 387; A. Dallos, A. Sisak, Z. Kulcsár, E.sz. Kováts, Pair-wise interactions by gas chromatography. VII. Interaction free enthalpies of solutes with secondary alcohol groups, J. Chromatogr. A 904 (2000) 211]. Obviously, the same data which are wrong in the nonpolar standard are also wrong in these solvents. The corrected data in the polar solvents are given in supplementary tables.