Methanolic Potassium Hydroxide Research Articles

21-monohydroxylation of 17β-acetyl steroids using phenyliodosodiacetate: one-step method and its limitations

Some 17β-acetyl steroids have been converted into 21-hydroxy-20-ketosteroids in high yields upon treatment with phenyliodosodiacetate in methanolic potassium hydroxide. Attempts to carry out the same reaction with several 17α-acetyl steroids derivatives were unsuccessful. The structure of substrates and products was confirmed by the IR, mass spectrometry, and 1H NMR techniques.

The coordination chemistry of unsymmetric N-capped tripodal NO3 ligands with iron(III), oxo-vanadium(V) and dioxo-molybdenum(VI) metal centres

The synthesis and characterisation of iron(III) [Fe(L1)]2 (1), oxo-vanadium(V) [VO(L1)] (2) and dioxo-molybdenum(VI) K[MoO2(L1)] (3) complexes supported by a partially unsymmetric N-capped tripodal NO3 ligand (L1) are reported. Complexes 1 and 2 were prepared by reactions of a proligand [H3L1] and their corresponding metal precursor (FeCl3 and VOCl3, respectively) in the presence of triethylamine in THF, while 3 was obtained in a similar manner by treating [MoO2(acac)2] (acac=acetylacetonate) with the same proligand and potassium hydroxide in methanol. The X-ray crystal structure of 1 illustrates a dimeric structure with a bis-(μ-phenoxo) Fe2O2 diamond core, and each iron centre bears a rare NO4 coordination sphere. The preparation of a previously unknown, fully unsymmetric N-capped tripodal NO3 proligand [H3L2] featuring three different phenolic arms is also described. Reaction of [H3L2] with VOCl3 yielded the oxo-vanadium(V) complex [VO(L2)] (4). Complexes 2–4 exist as monomers in solution and were characterised by NMR (1H and 13C), IR (for 3), mass spectrometry, and elemental analysis.

Influence of Fatty Acid Methyl Esters on Fuel properties of Biodiesel Produced from the Seeds Oil of <i>Curcubita pepo</i>

Oil extracted from the seeds of Curcubita pepo was transesterified using potassium hydroxide in methanol. Fatty acid methyl esters (FAME) profile of the produced diesel was analyzed using Gas chromatograph coupled with mass spectrophotometer (GC-MS). The results indicate the presence of methyl (12E)-octadecenotate as the dominant ester with approximate percentage by composition of 82.90%. Other esters detected were methyl tetradecanoate (0.4%), methyl eicosonoate (2.48%), methyl docosanoate (0.97%) methyl teracosanoate (0.47%). Some critical fuel parameters like oxidation stability, cetane number, iodine value and viscosity were correlated with the methyl ester composition and structural configuration. It was found that the cetane number and oxidation stability of the produced biodiesel is a function of the degree of unsaturation and long chain saturated factor. The profile of methyl esters in the biodiesel produced indicates its likelihood to be a viable fuel source for internal combustion engines.

Oximes as products in the reactions of 5‐substituted 2‐nitrothiophenes with arylacetonitriles

AbstractIt has been shown that reactions 5‐substituted 2‐nitrothiophenes with arylacetonitriles in the presence of potassium hydroxide in methanol lead to the formation of the new [2‐(hydroxyimino)‐5‐R‐3(2H)‐thienylidene](aryl)acetonitriles. Under proposed reaction conditions, the formation of thieno[2,3‐c]isoxazole was not the case. J. Heterocyclic Chem., (2011).

ChemInform Abstract: Unexpected Transformations of 1‐Aza‐1,3,4‐trienes in Alcoholic Potassium Hydroxide. New Classes of Aza Dienes.

Aza dienes [1, 2] and aza trienes [2, 3] are useful and important intermediates in the synthesis of both heterocyclic and open-chain polyfunctionalized compounds. We have discovered reactions of isothiocyanates with carbanions derived from alkenes [4], allenes [5], acetylenes [6], and butadienes [7], which have become an inexhaustible source of various aza diene and aza triene systems [8, 9]. Methyl N-ethyl-2-methoxybuta-2,3-dienimidothioate (I, 1-aza-1,3,4-triene) is a precursor of 1-ethyl-3methoxy-2-methylsulfanyl-1H-pyrrole (II), 5-methoxy-2-methyl-6-methylsulfanyl-2,3-dihydropyridine (III) [8], and 3-methoxy-2-methylsulfanyl-4,5-dihydro-3H-azepine (IV) [10] and is readily available from lithiated methoxyallene and ethyl isothiocyanate (Scheme 1). Using compound I as an example we performed for the first time a simple and convenient synthesis of unusual aza dienes, hemiaminal ethers with rare heteroatom substituents. It was found that treatment of 1-aza-1,3,4-triene I (without isolation from the reaction mixture) with a solution of potassium hydroxide in methanol at room temperature resulted in the formation of previously unknown methyl (Z)-2-methoxy-N-(1-methoxyethyl)but-2-enimidothioate (V) (Scheme 1) as a mixture of syn and anti isomers in ~45% yield (unoptimized). A probable reaction path involves isomerization of 1-aza-1,3,4-triene I into 2-aza-1,3,5-triene VI, addition of methanol at the C=N bond of VI, and subsequent [1,5]-H shift in adduct VII thus formed (Scheme 2). ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 1, pp. 146–149. © Pleiades Publishing, Ltd., 2011. Original Russian Text © N.A. Nedolya, O.A. Tarasova, O.G. Volostnykh, A.I. Albanov, B.A. Trofimov, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 1, pp. 146–149.

Reactions of methoxybenzylidene derivatives of 2,2-dimethyl-1,3-dioxane-4,6-dione and their saturated analogs with certain nucleophilic reagents

The reactions of the methoxybenzylidene derivatives of 2,2-dimethyl-1,3-dioxane-4,6-dione and their saturated analogs with potassium hydroxide in methanol, ammonia, and hydrazine hydrate were realized. The 1,2-bis(methoxybenzylidene)hydrazines, amides, and hydrazides of methoxybenzylidene-malonic acid, suitable for use as structural blocks in the synthesis of various structures based on them, were prepared and characterized.

Unexpected transformations of 1-aza-1,3,4-trienes in alcoholic potassium hydroxide. New classes of aza dienes

Aza dienes [1, 2] and aza trienes [2, 3] are useful and important intermediates in the synthesis of both heterocyclic and open-chain polyfunctionalized compounds. We have discovered reactions of isothiocyanates with carbanions derived from alkenes [4], allenes [5], acetylenes [6], and butadienes [7], which have become an inexhaustible source of various aza diene and aza triene systems [8, 9]. Methyl N-ethyl-2-methoxybuta-2,3-dienimidothioate (I, 1-aza-1,3,4-triene) is a precursor of 1-ethyl-3methoxy-2-methylsulfanyl-1H-pyrrole (II), 5-methoxy-2-methyl-6-methylsulfanyl-2,3-dihydropyridine (III) [8], and 3-methoxy-2-methylsulfanyl-4,5-dihydro-3H-azepine (IV) [10] and is readily available from lithiated methoxyallene and ethyl isothiocyanate (Scheme 1). Using compound I as an example we performed for the first time a simple and convenient synthesis of unusual aza dienes, hemiaminal ethers with rare heteroatom substituents. It was found that treatment of 1-aza-1,3,4-triene I (without isolation from the reaction mixture) with a solution of potassium hydroxide in methanol at room temperature resulted in the formation of previously unknown methyl (Z)-2-methoxy-N-(1-methoxyethyl)but-2-enimidothioate (V) (Scheme 1) as a mixture of syn and anti isomers in ~45% yield (unoptimized). A probable reaction path involves isomerization of 1-aza-1,3,4-triene I into 2-aza-1,3,5-triene VI, addition of methanol at the C=N bond of VI, and subsequent [1,5]-H shift in adduct VII thus formed (Scheme 2). ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 1, pp. 146–149. © Pleiades Publishing, Ltd., 2011. Original Russian Text © N.A. Nedolya, O.A. Tarasova, O.G. Volostnykh, A.I. Albanov, B.A. Trofimov, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 1, pp. 146–149.

ChemInform Abstract: Synthesis and Reactivity of (1S,4S,5S)-5-Bromo-1,3,3-trimethyl-N-nitro- 2-oxabicyclo(2.2.2)octan-6-imine. X-Ray Molecular Structure and Absolute Configuration of E and Z Isomers of (1S,4S)-5,5-Dibromo-1,3,3- trimethyl-N-nitro-2-oxabic

The potassium salt 2 of 1,3,3-trimethyl-N-nitro-2-oxabicyclo[2.2.2]octan-6-imine 1 reacted with bromine in acetic acid solution to give (1S,4S,5S)-5-bromo-1,3,3-trimethyl-N-nitro-2-oxa-bicyclo[2.2.2]octan-6-imine 3. Bromination of the salt 2 in methanolic potassium hydroxide afforded a mixture of (1S,4S)-5,5-dibromo-1,3,3-trimethyl-N-nitro-2-oxabicyclo[2.2.2]octan-6E-and -6Z-imine 4 and 5, whose X-ray crystal-structure determinations allowed their absolute configurations to be established. Bromination of monobromide 3 under different conditions gave the dibromide 4, which was converted into isomer 5 by storage in chloroform solution. Nitrimine 3 reacted with hydroxylamine hydrochloride and sodium hydroxide or piperidine to give (1S,4S,5S)-5-bromo- and -5-hydroxyamino-N-hydroxy-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-imine or (1S,4S,5S)-N-hydroxy-1,3,3-trimethyl-5-(piperidin-1-yl)-2-oxabicyclo[2.2.2]octan-6-imine. Reaction of compound 3 with aliphatic and aromatic primary amines afforded N-substituted (1S,4S,5S)-5-bromo-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-imines. Reduction of compound 3 with sodium cyanoborohydride gave (1S,4S,5S)-5-bromo-1,3,3-trimethyl-N-mtro-2-oxabicyclo[2.2.2]octan-6-amine, whereas consecutive treatment with potassium hydroxide and aq. hydrochloric acid afforded the less stable isomer (1S,4S)-5-bromo-1,3,3-trimethyl-N-nitro-2-oxabicyclo[2.2.2]oct-5-en-6-amine.

SYNTHESIS OF NEW ACTIVATED INDOLES; 3-(4’-BROMOPHENYL)-4,6-DIMETHOXY-2-METHYLINDOLE

3-(4'-Bromophenyl)-4,6-dimethoxy-2-methylindole has been synthesized from 4,6-dimethoxyaniline via the modified Bischler method. Reaction of 4,6-dimethoxyaniline with 2,4-dibromopropiophenone gave an aniline ketone in 85%, and then it was protected to give the amido ketone as a white solid. Cyclization of amido ketone was performed by trifluoroacetic acid and subsequent deprotection with potassium hydroxide in methanol afforded a white solid of 3-(4'-bromophenyl)-4,6-dimethoxy-2-methylindole in 86%. Keywords: 4,6-dimethoxyaniline, 2-methylindole, Bischler method

Isolation and Identification of Triglycerides and Ester Oligomers from Partial Degradation of Potato Suberin

Suberized cell walls from wound-healing potato tubers ( Solanum tuberosum ) were depolymerized under mild conditions using methanolic potassium hydroxide in order to investigate the chemical linkages present in this protective plant biopolymer. Analysis of the resulting soluble oligomeric fragments with HPLC, 1D and 2D NMR, LC/MS, and MS(n) methods allowed identification of several novel compounds: a family of homologous triglycerides, a family of homologous aliphatic ester trimers, and an ether-linked phenylacetic acid dimer. These findings illustrate the diversity of rigid and flexible molecular linkages present in both poly(aliphatic) and poly(aromatic) domains of potato suberin, and they point toward architectures that may account for its function as a potent hydrophobic barrier to water, thermal equilibration, and microbial pathogens.

Microwave-Enhanced Organic Syntheses for the Undergraduate Laboratory: Diels−Alder Cycloaddition, Wittig Reaction, and Williamson Ether Synthesis

Microwave heating enhanced the rate of three reactions typically performed in our undergraduate organic chemistry laboratory: a Diels−Alder cycloaddition, a Wittig salt formation, and a Williamson ether synthesis. Ninety-minute refluxes were shortened to 10 min using a laboratory-grade microwave oven. In addition, yields improved for the Wittig salt and ether preparations. The Diels-Alder cycloaddition of N-phenylmaleimide and 1,3-cyclohexadiene in absolute ethanol in a closed vessel and 130 °C gave 84−90% yields. Formation of the Wittig salt, benzyltriphenylphosphonium chloride, from triphenylphosphine and benzyl chloride gave yields greater than 90% when heated in acetonitrile at 200 °C Yields doubled in the Williamson ether synthesis of 2-ethoxynaphthalene, from 2-naphthol, methanolic potassium hydroxide, and iodoethane with microwave heating at 130 °C.

Syntheses and characterization of iron(II) and iron(III) complexes of a tripodal ligand derived from tris(2-aminoethyl)methane

The trihydrochloride salt of tris(2-aminoethyl)methane (tram·3HCl) was deprotonated in methanolic potassium hydroxide and reacted with three molar equivalents of imidazole-2-carboxaldehyde to give a new Schiff base ligand, HC(CH 2CH 2N CH-2ImH) 3. The ligand, H 3(1), was reacted in situ with iron(II)chloride tetrahydrate. Addition of excess sodium perchlorate resulted in the isolation of the dark red [FeH 3(1)](ClO 4) 2·KClO 4 . The neutral emerald green iron(III) tripodal complex, Fe(1), was prepared by the aerial oxidation of the iron (II) complex on addition of three equivalents of potassium hydroxide. The complexes are characterized by EA, IR, ESI-MS, Mössbauer, magnetic susceptibility and single crystal XRD. The spectroscopic and structural data support a low spin assignment for both the iron(II) and iron(III) complexes at 295 K. The overall conformation of the tram backbone in these complexes has the apical carbon atom, C ap, pointed away from the iron atom with an average non-bonded distance of 3.83 Å. However, C ap is distorted from tetrahedral geometry toward trigonal monopyramidal. This is indicated by a narrowing of the H–C ap–C angles, an expansion of the C–C ap–C angles and a compression along the C–H axis so that C ap approaches the plane defined by its three carbon substituents. Two unusual supramolecular features are exhibited in [FeH 3(1)](ClO 4) 2·KClO 4 . These are a polymeric [K(ClO 4) 3 2−] n anion and a bidentate hydrogen bonding donor, N imine C H–C imidazole–N imidazole H, on each arm of the tripodal ligand. Density Functional Theory (DFT) calculations using the B3LYP functional were performed on the low spin and high spin states of both complexes. B3LYP correctly predicts that the low spin state is favored in both systems and closely matches the important metrical parameters that are indicative of spin state. B3LYP shows that the C ap-out conformation of the tram backbone would be nearly identical in the low and high spin forms.

Syntheses and antibacterial studies of some 2-[5-(Aryl)-[1,3,4]oxadiazole-2-ylsulfanyl] alkanoic Acids

Some new 2-[5-(aryl)-[1,3,4]oxadiazole-2-ylsulfanyl]alkanoic acids were synthesized and studied for their antibacterial activity. These compounds were prepared from aromatic carboxylic acid hydrazides. Aromatic carboxylic acid hydrazides 1 on refluxing with carbon disulfide and methanolic potassium hydroxide and then on subsequent acidification with hydrochloric acid furnish 5-aryl-1,3,4-oxadiazole-2-thiones 2. 2-Chloro alkanoic acids react with 2 in alkaline media and on acidification yield the title compounds 3. These compounds were characterised by CHN analyses, IR, mass and 1H NMR spectral data. All the compounds were evaluated for their in vitro antibacterial activity against two Gram negative strains (Escherichia coli and Pseudomonas aeruginosa) and two Gram positive strains (Bacillus subtilis and Staphylococcus aureus) and their minimum inhibitory concentration (MIC) were determined.

Covalent Modification of the Wool Fiber Surface: Removal of the Outer Lipid Layer

This investigation provided a comparative assessment of strategies for the removal of 18-methyleicosanoic acid (18-MEA), and other surface bound lipids enveloping the wool fiber surface, by chemical and physical cleavage of the thioester bond. The removal of this lipid layer reveals an underlying proteinaceous layer, exposing functional chemical groups available for covalent attachment of new molecular or nanoparticulate entities by chosen treatments. Lipid removal treatments employing methanolic potassium hydroxide, t -butoxide in t-butanol, and aqueous hydroxylamine and a physical atmospheric pressure glow discharge (APGD) plasma treatment were compared. Treated wool fabrics were subsequently characterized by analysis of the exposed groups on the fiber surface by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), with the bulk surface properties of the fabrics assessed employing wettability testing techniques. An evaluation of chemical and plasma methods for removal of the surface bound lipid layer resulted in the selection of aqueous hydroxylamine/ non-ionic surfactant as the optimal treatment method for subsequent covalent attachment of novel entities by surface treatments. Optimized aqueous hydroxylamine treatment was found to remove up to 77% of the surface bound 18-MEA, providing a marked increase in surface wettability, without significantly affecting the handle of the treated fabric. Surface characterization demonstrated that the hydroxylamine treatment produces an increase in surface friction, with uniform and controlled removal of the surface lipid layer, and minimal surface oxidation of the surface thiols. Minimizing surface oxidation of thiols was a critical target of surface lipid removal in this study, as it maximizes the potential for subsequent surface modification via covalent attachment. The use of aqueous conditions, short reaction times, and moderate temperatures with hydroxylamine treatment are advantageous in comparison with treatments employing non-aqueous solvents such as methanol and anhydrous t-butanol. The economic and environmental advantages of an aqueous, effective, and non-damaging approach to surface lipid removal highlight this approach as a potential avenue for future textile application of novel wool surface chemistries.

Isolation and Identification of Oligomers from Partial Degradation of Lime Fruit Cutin

Complementary degradative treatments with low-temperature hydrofluoric acid and methanolic potassium hydroxide have been used to investigate the protective biopolymer cutin from Citrus aurantifolia (lime) fruits, augmenting prior enzymatic and chemical strategies to yield a more comprehensive view of its molecular architecture. Analysis of the resulting soluble oligomeric fragments with one- and two-dimensional NMR and MS methods identified a new dimer and three trimeric esters of primary alcohols based on 10,16-dihydroxyhexadecanoic acid and 10-oxo-16-hydroxyhexadecanoic acid units. Whereas only 10-oxo-16-hydroxyhexadecanoic acid units were found in the oligomers from hydrofluoric acid treatments, the dimer and trimer products isolated to date using diverse degradative methods included six of the seven possible stoichiometric ratios of monomer units. A novel glucoside-linked hydroxyfatty acid tetramer was also identified provisionally, suggesting that the cutin biopolymer can be bound covalently to the plant cell wall. Although the current findings suggest that the predominant molecular architecture of this protective polymer in lime fruits involves esters of primary and secondary alcohols based on long-chain hydroxyfatty acids, the possibility of additional cross-linking to enhance structural integrity is underscored by these and related findings of nonstandard cutin molecular architectures.

Determination of methylmercury in fish and seafood using optimized digestion and derivatization followed by gas chromatography with atomic emission detection

Mercury is an environmental contaminant that appears in different chemical forms. Organic forms of mercury, such as methylmercury, can occur in marine organisms like fish and shellfish and are far more toxic than the inorganic form. It is therefore vital to have refined analytical methods for the different mercuric species in order to evaluate the potential risk for seafood consumers. The aim of our investigations was to develop a simple, robust and valid method for differentiation of the mercury species in marine organisms. Different alkaline and acidic digestion procedures were evaluated. The best performing methodology consisted of digestion of 0.5 g sample in methanolic potassium hydroxide solution. After derivatization with sodium tetraethylborate and extraction of the ethylated mercury species using n-hexane, a quantitative determination of the extract using gas chromatography, combined with atomic emission detection, was possible. The procedure was shown to be selective and sensitive with a limit of detection of 6.1 μg/kg for methylmercury. The average recovery for the full procedure was 91 ± 19%. A preliminary survey of seafoods confirmed the previous observation that the proportion of methylmercury in the total mercury can vary widely, up to a complete occurrence as methylmercury.

Human breast milk enrichment in conjugated linoleic acid after consumption of a conjugated linoleic acid–rich food product: a pilot study

Human breast milk is a complex mixture of organic and inorganic compounds. Some compounds, such as conjugated linoleic acid (CLA), come partly from the mother's diet and are produced by the mother's body and secreted into the milk. Although several studies have examined the effect of chronic CLA supplementation on breast milk CLA appearance, little is known about the transfer of food CLA to breast milk over the short term. The objective of this study was to conduct a preliminary analysis of the kinetics of CLA appearance in breast milk over the short term. Seven women expressed breast milk at 4- to 6-hour intervals for 2 days after eating either CLA-enriched (1912 mg CLA) or control (231 mg CLA) cookies. Milk samples were freeze-dried, fatty acid methyl esters were prepared using methanolic-potassium hydroxide (KOH), and CLA isomers were quantified by gas chromatography. Analysis revealed the following: (1) CLA enrichment of total fatty acids in the breast milk for 48 hours post ingestion of the CLA-enriched cookies was 2.9-fold above control; (2) total breast milk CLA content for 48 hours post CLA-enriched cookies ingestion was 46% greater than post CLA-moderate cookies ingestion; (3) after ingestion of the CLA-enriched cookies, breast milk CLA enrichment plateaued between 8 to 28 hours. This preliminary study suggests that breast milk fatty acids are enriched in CLA compared to control within 28 hours after the ingestion of a CLA-rich food product and invites further research on the extent and timing with which breast milk composition reflects dietary CLA content.

Crystal Structure of [1-Phenyl-3-(4-nitrophenyl)triazenido 1-oxide-.KAPPA.2N3,O]-bis(triphenylphosfine)silver(I), [Ag(O2-NC6H4NNNOC6H5)(C18H15P)2

The reaction between [Ag(PPh3)3(NO3)] and 1-phenyl-3-(4-nitrophenyl) triazene 1-oxide desprotonated with potassium hydroxide in methanol yields crystalline [Ag(O2NC6H4NNNOC6H5)(C18H15P)2], the first mononuclear triazenido 1-oxide complex of Ag(I) including a [Ag(PPh3)2]+ fragment. In the asymmetric title complex, the coordination geometry about the Ag+ ion is tetrahedral, with one triazenido 1-oxide anion acting as a bidentate ligand (four-electron donor). The crystal belongs to the monoclinic system, space group P21/c with the cell dimensions a = 19.551(7), b = 19.342(9), c = 11.124(6)A, β = 95.453(15)°, V = 4187(3)A3, Z = 4.

Chemoselective synthesis of novel thiatriazolophanes

Bis-[4-alkyl/aryl-5-thia-1,2,4-triazoles] were prepared by fusion of diacids and thiosemicarbazides by condensation of aromatic acid hydrazides with isothiocyanate. Chemoselective alkylation of these bis-[4-alkyl/aryl-5-thia-1,2,4-triazoles] with 1,w-dihaloalkanes in presence of potassium hydroxide in aqueous methanol afforded novel N-alkyl/aryl thiatriazolophanes.

(E)-3-(Benzo[b]thiophen-2-yl)-2-(3,4,5-trimethoxyphenyl)acrylonitrile and (Z)-3-(benzo[b]thiophen-2-yl)-2-(3,4-dimethoxyphenyl)acrylonitrile

The title compounds, C20H17NO3S, (I), and C19H15NO2S, (II), were prepared by the reaction of benzo[b]thiophene-2-carbaldehyde with (3,4,5-trimethoxyphenyl)acetonitrile and (3,4-dimethoxyphenyl)acetonitrile, respectively, in the presence of methanolic potassium hydroxide. In (I), the C=C bond linking the benzo[b]thiophene and the 3,4,5-trimethoxyphenyl units has E geometry, with dihedral angles between the plane of the bridging unit and the planes of the two adjacent ring systems of 5.2 (3) and 13.1 (2) degrees, respectively. However, in (II), the C=C bond has Z geometry, with dihedral angles between the plane of the bridging unit and the planes of the adjacent benzo[b]thiophene and 3,4-dimethoxyphenyl units of 4.84 (17) and 76.09 (7) degrees, respectively. There are no significant intermolecular hydrogen-bonding interactions in the packing of (I) and (II). The packing is essentially stabilized via van der Waals forces.