Alcoholic Hydroxy Research Articles

Molecular insights into dissolution of lignin bunch in ionic liquid-water mixture for enhanced biomass conversion

Globally, the shift towards lignocellulosic biorefinery has opened avenues for valorizing lignin, a majorly accumulated recalcitrant by-product. A targeted lignin processing by ionic liquid-cosolvent mixtures can be an effective biomass conversion strategy. An understanding of lignin-ionic liquid dissolution can enable in designing a significant lignin processing technique to synthesis lignin-based renewable products. Here, we explored the molecular interaction during the dissolution of lignin containing five guaiacyl decamer chains in various (1-Ethyl-3-Methylimidazolium Acetate) EmimOAc-water mixtures using molecular dynamics simulation. The analysis showed that in only water, lignin formed a compact aggregate. Nevertheless, in 50%, 80%, and 100% EmimOAc-water, lignin underwent a segregated chain disentanglement with widespread dynamic motion. A detailed multifaceted analysis of Emim+, OAc− and water distribution on the polar and non-polar sites of lignin units was illustrated. An effective lignin dissolution was observed for 50% and 80% EmimOAc-water systems. The OAc− distribution was stronger around lignin's alkyl chains and alcoholic hydroxy groups. The Emim+ tails significantly impacted the benzene ring, whereas Emim+ heads were distributed around methoxy and hydroxy groups. Altogether, this study explores the lignin dissolution at atomistic level in EmimOAc-water mixtures; these understanding could serve as a cornerstone for engineering new ionic liquid-mediated lignin biorefinery.

Investigation of phase II metabolism of 11-hydroxy-\u0394-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-\u0394-9-tetrahydrocannabinol-glucuronide

(−)-Δ-9-tetrahydrocannabinol ((−)-Δ-9-THC) is the main psychoactive constituent in cannabis. During phase I metabolism, it is metabolized to (−)-11-hydroxy-Δ-9-tetrahydrocannabinol ((−)-11-OH-Δ-9-THC), which is psychoactive, and to (−)-11-nor-9-carboxy-Δ-9-tetrahydrocannabinol ((−)-Δ-9-THC-COOH), which is psychoinactive. It is glucuronidated during phase II metabolism. The biotransformation of (−)-Δ-9-tetrahydrocannabinol-glucuronide ((−)-Δ-9-THC-Glc) and (−)-11-nor-9-carboxy-Δ-9-tetrahydrocannabinol-glucuronide ((−)-Δ-9-THC-COOH-Glc) is well understood, which is mainly due to the availability of commercial reference standards. Since such a standardized reference is not yet available for (−)-11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide ((−)-11-OH-Δ-9-THC-Glc), its biotransformation is harder to study and the nature of the glucuronide bonding—alcoholic and/or phenolic—remains unclear. Consequently, the aim of this study was to investigate the biotransformation of (−)-11-OH-Δ-9-THC-Glc in vitro as well as in vivo and to identify the glucuronide by chemically synthesis of a reference standard. For in vitro analysis, pooled human S9 liver fraction was incubated with (−)-Δ-9-THC. Resulting metabolites were detected by high-performance liquid chromatography system coupled to a high-resolution mass spectrometer (HPLC-HRMS) with heated electrospray ionization (HESI) in positive and negative full scan mode. Five different chromatographic peaks of OH-Δ-9-THC-Glc have been detected in HESI positive and negative mode, respectively. The experiment set up according to Wen et al. indicates the two main metabolites being an alcoholic and a phenolic glucuronide metabolite. In vivo analysis of urine (n = 10) and serum (n = 10) samples from cannabis users confirmed these two main metabolites. Thus, OH-Δ-9-THC is glucuronidated at either the phenolic or the alcoholic hydroxy group. A double glucuronidation was not observed. The alcoholic (−)-11-OH-Δ-9-THC-Glc was successfully chemically synthesized and identified the main alcoholic glucuronide in vitro and in vivo. (−)-11-OH-Δ-9-THC-Glc is the first reference standard for direct identification and quantification. This enables future research to answer the question whether phenolic or alcoholic glucuronidation forms the predominant way of metabolism.

Synthesis and Self‐Aggregation of Chlorophyll‐a Derivatives with Ethynylene and Phenylene Groups Inserted Between the Hydroxymethyl Group and the Chlorin π‐Skeleton

AbstractChlorophyll(Chl)‐a derivatives containing some rigid linkers in the C3‐substituent, inserted between a hydroxymethyl group and a zinc 131‐oxo‐chlorin moiety, were synthesized as models of bacteriochlorophyll‐c/d/e molecules in the main light‐harvesting antennae (chlorosomes) of photosynthetic green bacteria. These model compounds were synthesized from a C3‐ethynylated Chl‐a derivative via several coupling reactions, and the lengths of the linkers were controlled by ethynylene and p‐phenylene groups. In less polar organic solvents or an aqueous micellar solution, some derivatives self‐aggregated in a J‐type fashion similar to that observed in natural chlorosomes, which was confirmed with UV/Vis absorption and CD spectroscopies. Their self‐aggregation abilities were dependent on the length of the inserted linkers and the conformation of the propargylic/benzylic alcoholic hydroxy groups.

In vitro stereospecific hydration activities of the 3-vinyl group of chlorophyll derivatives by BchF and BchV enzymes involved in bacteriochlorophyll c biosynthesis of green sulfur bacteria.

The photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum produces bacteriochlorophyll (BChl) c pigments bearing a chiral 1-hydroxyethyl group at the 3-position, which self-aggregate to construct main light-harvesting antenna complexes, chlorosomes. The secondary alcoholic hydroxy group is requisite for chlorosomal aggregation and biosynthesized by hydrating the 3-vinyl group of their precursors. Using recombinant proteins of Cba. tepidum BchF and BchV, we examined in vitro enzymatic hydration of some 3-vinyl-chlorophyll derivatives. Both the enzymes catalyzed stereoselective hydration of zinc 3-vinyl-8-ethyl-12-methyl-bacteriopheophorbide c or d to the zinc 31 R-bacteriopheophorbide c or d homolog, respectively, with a slight amount of the 31 S-epimric species. A similar R-stereoselectivity was observed in the BchF-hydration of zinc 3-vinyl-8-ethyl- and propyl-12-ethyl-bacteriopheophorbides c, while their BchV-hydration gave a relatively larger amount of the 31 S-epimers. The in vitro stereoselective hydration confirmed the in vivo production of the S-epimeric species by BchV. The enzymatic hydration for the above 8-propylated substrate proceeded more slowly than that for the 8-ethylated, and the 8-isobutylated substrate was no longer hydrated. Based on these results, biosynthetic pathways of BChl c homologs and epimers are proposed.

Reductive Nucleation of Palladium Nanoparticles on a Cycloolefin Polymer Surface Oxidized with Active Oxygen Species Generated by Vacuum Ultraviolet Excitation

Abstract The ability to reduce palladium (Pd) ions to Pd nanoparticles has been provided on the surface of cycloolefin polymer (COP). The origin of this reductive function is aldehyde and alcoholic hydroxy groups formed by oxidizing the COP surface with active oxygen species, which were generated through the irradiation of atmospheric oxygen and water molecules with vacuum ultraviolet light of 172 nm in wavelength. The Pd nanoparticles successfully served as catalysts for electroless plating.

ChemInform Abstract: Synthesis of Alkyl (4,5‐Dichloroisothiazol‐3‐yl) Ketones and Some of Their Derivatives.

Reactions of 4,5-dichloroisothiazol-3-ylcarbonitrile with methylmagnesium iodide and ethylmagnesium bromide afforded the corresponding alkyl (4,5-dichloroisothiazol-3-yl) ketones. The reaction of (4,5-dichloroisothiazol-3-yl) methyl ketone with morpholine and piperidine provided 5-morpholino-(piperidino)-substituted derivatives, by the action of sodium borohydride in 2-propanol the keto group was reduced to alcoholic hydroxy group. The bromination of (4,5-dichloroisothiazol-3-yl) methyl ketone with elemental bromine gave bromomethyl (4,5-dichloroisothiazol-3-yl) ketone, whose reaction with thiourea resulted in 2-amino-4-(4,5-dichloroisothiazol-3-yl)thiazole.

Synthesis of alkyl (4,5-Dichloroisothiazol-3-yl) ketones and some of their derivatives

Reactions of 4,5-dichloroisothiazol-3-ylcarbonitrile with methylmagnesium iodide and ethylmagnesium bromide afforded the corresponding alkyl (4,5-dichloroisothiazol-3-yl) ketones. The reaction of (4,5-dichloroisothiazol-3-yl) methyl ketone with morpholine and piperidine provided 5-morpholino-(piperidino)-substituted derivatives, by the action of sodium borohydride in 2-propanol the keto group was reduced to alcoholic hydroxy group. The bromination of (4,5-dichloroisothiazol-3-yl) methyl ketone with elemental bromine gave bromomethyl (4,5-dichloroisothiazol-3-yl) ketone, whose reaction with thiourea resulted in 2-amino-4-(4,5-dichloroisothiazol-3-yl)thiazole.

Metal‐binding Sites of N‐Acetylneuraminic Acid

AbstractSialic acid represents a group of thirty derivates of neuraminic acid with various substituents at the amino residue and the alcoholic hydroxy groups. We analysed the behaviour of the tetracoordinated metal ions palladium(II) and silicon(IV) against the most important derivative N‐acetylneuraminic acid (NANA). The molecular structures were assigned by a combined 1H, 13C and 29Si NMR‐spectroscopic approach. Despite the presence of many different functional groups, the coordination chemistry of NANA with PdII follows established rules. Coordination via the N‐acetyl‐group – sterically impossible with PdII – was realised with SiIV.

Reaction of 2-(trifluoromethyl)chromones with pyridoxal: Formation of 1-benzopyranooxepino- and 1-benzopyranopyranopyridines

Pyridoxal undergoes oxa-Michael initiated ring closure with 2-(trifluoromethyl)chromones giving 11a,13-dihydro-6H-1-benzopyrano[3′,2′:6,7]oxepino[3,4-c]pyridin-6-ones and 6H,11aH-1-benzopyrano[3′,2′:5,6]pyrano[2,3-c]pyridin-6-ones. Participation of alcoholic hydroxy group of pyridoxal in the initial oxa-Michael addition leads to the former product and that of the phenyl hydroxy group to the later one.

Scientific Meetings: Some Aspects of Pharmacological Chemistry

Abstract A Summary of Three University Lectures given in the Department of Pharmacology, University College, London. January-February, 1949. Only the symptomatic drugs were considered in this series. The first lecture dealt with the significance of total chemical constitution and the theories of modes of drug action1. Examples indicating constitution-action-parallelism were quoted, but it was emphasised that much more data were required to produce a more secure basis for a rational approach. In the next lecture the work on the analgesic substances, particularly on morphine, was discussed2. On the third occasion the chemistry of the parasympathomimetics and parasympatholytics was considered. These drugs are based on acetylcholine, which is not strange to the organism. Acetylcholine has three pharmacological actions, muscarinic, nicotinic and under certain conditions, curare-like. As an ester, it is hydrolysed by the enzymes, cholinesterases of blood cells and plasma and transformed into the weakly active choline. Its re-synthesis may be due to the action of an acetylase, the co-enzyme of which may consist partly of pantothenic acid. Its existence was demonstrated by Feldberg and Mann in brain and by Bülbring and Burn in rabbit heart auricles. There exists also an inactive acetylcholine complex, the formation of which may partly explain the disappearance of the neurohormone. That it also occurs in plants was shown by Feldberg’s discovery of acetylcholine in the stinging nettle. The instability and amphotropic properties of acetylcholine stimulated the pharmacological chemist to synthesise substances with more sustained and clear-cut action. When considering substances which, like acetylcholine, possess parasympathomimetic action, Pfeiffer’s theory of prosthetic3 distances comes to mind, postulating an optimum distance between the N-methyl group and the two oxygen atoms. Thus it can be understood why three natural drugs–muscarine, pilocarpine, and arecoline–show, on the whole, lower activities and have never gained clinical importance. Virtual changes of the acetylcholine molecule itself have produced evidence that the free aminoalkanols are very much weaker and that, for the existence of full muscarinic action, the alcohol group must be esterified and the nitrogen carry at least two methyl groups. When the chain of the alcohol or the acid is elongated, activity falls considerably. There is one exception, and that is when the aminoalkanol chain is branched, as in mecholyl which shows strong muscarinic effect. Acetic acid has been exchanged against other acidic residues, such as carbamic acid in carbachol, thioacetic acid, etc. Transformation of the choline ester into choline ethers produces more stable but less active compounds. An ether-like product was made by Fourneau (2268 F) and found to be very potent indeed. Another ether-like compound is Esmodil which contains a double bond like arecoline and croton betaine methyl ester. The latter, carrying the nitrogen on the acidic side, is very much like acetylcholine though weaker. While choline itself shows very little activity, 3-hydroxymethylpyridine, the alcohol corresponding to nicotinic acid, possesses interesting parasympathomimetic properties. Other aromatic compounds with phenolic groups in place of alcoholic hydroxy groups, show remarkable properties, especially when esterified with carbamic acid.

Self-aggregation of synthetic multi-hydroxylated zinc chlorophylls

A series of zinc 3-hydroxymethyl-13 1-oxo-(bacterio)chlorins possessing additional hydroxy group(s) on the B-ring were synthesized as models of bacteriochlorophylls- c/ d/ e, self-aggregative light-harvesting pigments of green photosynthetic bacteria. Tertiary and secondary alcoholic moieties on the 7- and/or 8-position(s) did not significantly interact with any other functional groups in their well-ordered self-aggregates. In contrast, the less sterically hindered primary alcoholic hydroxy group at the 7- and 8-substituents slightly caused random orientations of their molecular transition dipole moments in the supramolecule by unfavorable hydrogen bonding, which was competitive with the original 3 1-OH.

Microwave-Accelerated Selective Acylation of (Hydroxyalkyl)phenols Using Acid Chlorides

Highly selective acylation of the alcoholic hydroxy group can be achieved with (hydroxyalkyl)phenols carrying both alcoholic and phenolic hydroxyls by the use of the most common acylating agents, acid chlorides, under microwave irradiation.

Development and application of electrospray-active derivatization reagents for hydroxysteroids

New derivatization reagents, 1-(2,4-dinitro-5-fluorophenyl)-4-methylpiperazine (PPZ) and 4-(4-methyl-1-piperazyl)-3-nitrobenzoyl azide (APZ), were developed for the liquid chromatography–electrospray ionization-mass spectrometric (LC–ESI-MS) determination of steroids having a hydroxy group. PPZ reacted with a phenolic hydroxy group in estrogens. After quaternarization of the PPZ-estrogens with methyl iodide, the resulting derivatives provided more than a 2000-fold higher sensitivity compared to the intact estrogens. After derivatization of steroids having an alcoholic hydroxy group (5-ene-steroids or 5α-reduced steroids) with APZ followed by methylation, their detection responses increased more than 500 times. These derivatization procedures coupled with LC–ESI-MS/MS were successfully used for the determination of estrogens in the serum and prostatic 5α-dihydrotestosterone.

Synthesis and lipase-catalyzed resolution studies on novel (±)-2-(2-acetoxyethyl)-4-arylmethyl-3-oxo-3,4-dihydro-2 H-1,4-benzoxazine-6-carboxylates

Five novel methyl (±)-2-(2-acetoxyethyl)-4-arylmethyl-3-oxo-3,4-dihydro-2 H-1,4-benzoxazine-6-carboxylates have been synthesized and their lipase-catalyzed resolution via stereoselective deacetylation of acetoxyethyl moiety present in the molecule studied. It has been observed that Novozyme ®-435 in THF efficiently catalyses the enantioselective deacetylation of these acetoxyethyl dihydrobenzoxazines leading to the formation of optically enriched methyl (+)-4-arylmethyl-2-(2-hydroxyethyl)-3-oxo-3,4-dihydro-2 H-1,4-benzoxazine-6-carboxylates. The biocatalytic reaction was found to be chemoselective alongwith being enantioselective, because the lipase exclusively catalyses the deesterification of the ester function derived from the alcoholic hydroxy moiety in the molecule over the one derived from the aromatic carboxylic acid group.

1,4- and 2,4-substituted-1,2,3-triazoles as potential potassium channel activators. VII

New 1,4- and 2,4-substituted 1,2,3-triazole derivatives were synthesized and tested as potential BK Ca channel openers, as a part of a research program, which hypothesizes a pharmacophoric structure containing the 1,2,3-triazole ring. The structure–activity relationships were studied introducing some structural changes concerning molecular geometry and the presence of a hydrogen bond donor as a primary amino group and a phenolic or alcoholic hydroxy function. The compounds were prepared by nucleophilic substitution on the 1,2,3-triazole ring and by 1,3-dipolar cycloaddition of azides to selected alkynes and to phenylacetone. The new compounds tested on rat aortic rings did not exhibit any significant vasorelaxing activity.

AlIII ion complexes of saccharic acid and mucic acid: a solution and solid-state study.

The Al(III)-binding abilities of two aldaric acids, D-saccharic acid and mucic acid (the neutral form is denoted as H(2)L), were studied in solution by means of pH potentiometric, (1)H and (13)C NMR, and ESI-MS techniques. The most probable conformations and isomeric binding modes of the complexes formed in solution were determined by density functional theory (DFT) calculations. A solid D-saccharic acid complex K(2)[[Al(LH(-2))(H(2)O)](2)].H(2)O was isolated and crystallographically characterised. The two alcoholic hydroxy groups alpha to the terminal COO(-) groups were found to take part in the coordination, but in different ways. One of them coordinates in a bridging mode. Detailed ESI-MS and NMR studies proved that the complex retains its structure in solution. However, depending on the ligand and the pH, such complexes may exist in two isomeric forms. DFT calculations on the ion [[Al(LH(-2))(H(2)O)](2)](2-) revealed that several orbitals participate in stabilizing the dimeric arrangement.

Hydrogen bonding patterns and crystal packing in azobenzene-carboxylic acids

X-ray structures of four substituted azobenzene-carboxylic acids have been determined. The crystal packing of the compounds has been analyzed in terms of three main features: parallel placement of the long molecular axes, lateral contacts of (offset) face to face and face to edge types among aromatic rings and hydrogen bonding between carboxy and/or alcoholic hydroxy groups. Hydrogen bonding patterns of the dimer, catemer and expanded dimer types have been found, as well as supramolecular architectures such as chains, rows, sheets and networks.

Co-ordination of transition metal ions by galactaric acid: a potentiometric and spectroscopic study

A solution study on the ability of galactaric acid [GalaH 2, HOOC(CH) 4COOH] in the complexation of biological metal ions such as Co(II) and Ni(II) and toxic metal ions such as Cd(II), Pb(II) and Hg(II), is reported. The stability constants of the complex species are determined by means of potentiometric measurements. Galactaric acid behaves as chelate ligand through carboxylic oxygen and α-hydroxy group towards Co(II) and Ni(II), while in the Pb(II) and Cd(II) containing system it co-ordinates the metal ion with carboxylic oxygen and two alcoholic hydroxy groups. The prevailing species at acidic or neutral pH is [MGala] which is also isolated in the solid state and characterized by means of IR spectroscopy. On increasing pH, the [MGalaH −1] − species is also formed where the co-ordinated OH group undergoes deprotonation in all metal ion complexes except those with Hg(II), where the co-ordination of hydroxide ion is suggested as the precipitation of the metal hydroxide occurs at pH 7.

A useful enantioselective synthesis of chroman-2-ylmethanol

An enantioselective synthesis of chromanylmethanol is described. An allylic alcohol moiety is, first, introduced on the aromatic ring through a Claisen transposition. Chirality is then introduced through asymmetric Sharpless epoxidation on the allylic alcohol moiety. Cyclization into the benzopyran ring is achieved by an intramolecular coupling between the tertiary alcoholic hydroxy and the hydroquinone moiety with an excellent retention of configuration.

Binding ability of sialic acid towards biological and toxic metal ions. NMR, potentiometric and spectroscopic study

The binary complexes of 5-amino-3,5-dideoxy- d-glycero- d-galactononulosic acid (NANA), commonly called N-acetyl neuraminic acid, formed with biological metal ions such as Co(II) and Cu(II) and toxic metal ions such as Cd(II) and Pb(II) were investigated in aqueous solution by means of potentiometry, UV and NMR spectroscopy. The corresponding ternary systems with 2,2′-bipyridine were studied in aqueous solution by potentiometry and UV spectroscopy. NANA co-ordinates all metal ions, in both binary and ternary systems through the carboxylic group (protonated or deprotonated according to pH), pyranosidic ring oxygen and glycerol chain alcoholic hydroxy groups. The prevailing species in the pH range 2–7 are of [M(NANA) 2] type, and their stability constants are greater than those of simple carboxylate complexes. Above pH 7, the species [M(NANA) 2OH] − are also formed, but they do not prevent the precipitation of metal hydroxides. This work provides information on the solution state chemistry of NANA in the presence of bivalent metal ions; its great affinity for the toxic metals Cd(II) and Pb(II), near physiological conditions, and the relatively high stability of the complex species found may also account for the mechanism of toxicity.