Presence Of NaHCO3 Research Articles

N-Alkylations of chitosan promoted with sodium hydrogen carbonate under aqueous conditions

Chitosan was reacted with four alkyl halides, monobromoacetic acid, benzyl bromide, 2-bromoethanol, and monochloroacetic acid, in the presence of NaHCO3 in water. Chemical structures, degrees of substitution, and degrees of polymerization of reaction products were studied by FT-IR, NMR, SEC-MALLS, and elementary analyses. All alkyl groups were introduced selectively into the C2-amine groups of chitosan, and the yields of the N-alkyl chitosans were >90% by this method. N-Carboxymethyl chitosan (N-CMCh) and N-benzyl chitosan (N-BnCh) with high degrees of substitution (DS) up to 200% and 164% of the C2-amine groups, respectively, were obtained; N,N-dicarboxymethyl and N,N-dibenzyl chitosans were obtained in high yields. Degrees of polymerization (DP) of N-CMCh decreased during the reaction. The greater the amount of monobromoacetic acid added, the lower the DP of N-CMCh.

Influence of salts on the subcritical water-gas shift reaction

The water-gas shift reaction is the key reaction to produce hydrogen by hydrothermal biomass gasification. Salts are ingredients of biomass and accelerate the water-gas shift reaction. In this work, the influences of the NaHCO3 and the KHCO3 on water-gas shift reaction (WGSR) were investigated at 10 and 23MPa and 230–300°C. The presence of NaHCO3 and KHCO3 promotes the WGSR significantly and to the same extend. Additionally, sodium and potassium formate salts are formed from the carbonates. The water-gas shift reaction rate in the presence of salts is found to be:1.16×104 (l mol−1)0.5 s−1 e(−9155 K/T) [CO][NaHCO3]0.5.

Histidine derivatives as tridentate chelators for the fac-[M I(CO) 3] (Re, 99mTc, 188Re) core: Synthesis, structural characterization, radiochemistry and stability

The development of new rhenium(I)- and technetium(I)–tricarbonyl complexes can lead to potentially useful radiopharmaceuticals. In this work, the synthesis of the neutral rhenium complex fac-[Re(NSO)(CO) 3], Re-1, where NSO is the tridentate chelating agent 3-(1H-imidazol-4-yl)-2-( p-methoxy-benzylthio)propionic acid 1 was effected via reaction with (NEt 4) 2[ReBr 3(CO) 3] in the presence of NaHCO 3. Complex Re-1 crystallized from methanol/water and its structure was established by IR, 1H and 13C NMR spectroscopies, ESI-MS analysis and X-ray crystallography. When the reaction took place in the absence of base, HPLC analysis revealed the presence of a second product (yield 7%) that was assigned by NMR and ESI analysis to be complex fac-[Re(NS)(CO) 3Br] Re-2. At the tracer level, the analogous complexes fac-[ 99mTc(NSO)(CO) 3], 99mTc-1 and fac-[ 188Re(NSO)(CO) 3], 188 Re-1, were synthesized and their radiochemical stability in physiological conditions was determined. Both tracer complexes 99m Tc-1 and 188 Re-1 are stable in solution as well as in the presence of strongly coordinating agents like histidine or cysteine.

Solvent-Free One-Pot Synthesis of Spiro[indoline-3,4′(1H′)-pyrano[2,3-c]pyrazol]-2-one Derivatives by Grinding

The solvent-free one pot synthesis of spiropyranyl-oxindole in the presence of NaHCO3 under grinding has been achieved. This process is simple, fast, efficient and environmentally benign.

Deliberate design of an acentric diamondoid metal-organic network

Reaction of 2.5-dicarboxy-1-methylpyridinium (DCMP) chloride and Zn(NO 3) 2·6H 2O in the presence of NaHCO 3 in water gave an expected acentric diamondoid network [Zn(DCMP) 2] with a three-fold interpenetration. With long Zn–Zn separations, very large cavities are formed within each diamondoid network with high propensity to interpenetration, which makes it show a promising non-linear optical property with SHG efficiency approximately 7 times higher than that of potassium dihydrogen phosphate (KDP). The design strategy of ligand through methylation of the corresponding pyrdinecarboxylic acid can be extended to other widely used carboxylic acids, more importantly, to lead to an unsymmetric bifunctional bridging ligand, which is essential for generating polar solids.

Smart gelation of chitosan solution in the presence of NaHCO 3 for injectable drug delivery system

In situ gelling systems are attractive as injectable vehicles for drug delivery. The present work described a novel gelation process of acidic chitosan solution in the presence of sodium bicarbonate (NaHCO 3). The NaHCO 3 concentration played an important role in this gelling system. When it came within the appropriate range, the chitosan/NaHCO 3 system would stay at sol state in certain condition and showed sol–gel transition from the top to the bottom after heating. The rheological properties of the gelling system, as well as the morphology and erosion behavior of the formed chitosan hydrogels were evaluated as a function of the NaHCO 3 concentration in sols. The hydrogels showed porous morphologies with some diversification depending on the NaHCO 3 concentration, which also affected their erosion behaviors and drug release rates. Moreover, the gelation mechanism of such chitosan/NaHCO 3 system was studied and proposed as the formation of three-dimensional chitosan network with physical junctions thanks to the deprotonation of –NH 3 + in chitosan accompanying with the gradual neutralization between HCO 3 − and acid. In vivo gelation test was also performed by the dorsal subcutaneous injection of chitosan/NaHCO 3 solution in rat. The formation of in situ gels suggested such system promising applications in injectable drug delivery system.

Zeta potential of anoxygenic phototrophic bacteria and Ca adsorption at the cell surface: Possible implications for cell protection from CaCO3 precipitation in alkaline solutions

Electrophoretic mobility measurements and surface adsorption of Ca on living, inactivated, and heat-killed haloalkaliphilic Rhodovulum steppense, A-20s, and halophilic Rhodovulum sp., S-17-65 anoxygenic phototrophic bacteria (APB) cell surfaces were performed to determine the degree to which these bacteria metabolically control their surface potential equilibria. Zeta potential of both species was measured as a function of pH and ionic strength, calcium and bicarbonate concentrations. For both live APB in 0.1M NaCl, the zeta potential is close to zero at pH from 2.5 to 3 and decreases to −30 to −40mV at pH of 5–8. In alkaline solutions, there is an unusual increase of zeta potential with a maximum value of −10 to −20mV at a pH of 9–10.5. This increase of zeta potential in alkaline solutions is reduced by the presence of NaHCO3 (up to 10mM) and only slightly affected by the addition of equivalent amount of Ca. At the same time, for inactivated (exposure to NaN3, a metabolic inhibitor) and heat-killed bacteria cells, the zeta potential was found to be stable (−30 to −60mV, depending upon the ionic strength) between pH 5 and 11 without any increase in alkaline solutions. Adsorption of Ca ions on A-20s cells surface was more significant than that on S-17-65 cells and started at more acidic pHs, consistent with zeta potential measurements in the presence of 0.001–0.01mol/L CaCl2. Overall, these results indicate that APB can metabolically control their surface potential to electrostatically attract nutrients at alkaline pH, while rejecting/avoiding Ca ions to prevent CaCO3 precipitation in the vicinity of cell surface and thus, cell incrustation.

PHEMA cryogel for in-vitro removal of anti-dsDNA antibodies from SLE plasma

Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA) cryogel carrying DNA was used in the removal of anti-dsDNA antibodies from systemic lupus erythematosus (SLE) patient plasma. The PHEMA cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomer frozen inside a plastic syringe. After thawing, the PHEMA cryogel contains a continuous matrix having interconnected macropores of 10–200 μm size. Pore volume in the PHEMA cryogel was 67.5%. Ester groups in the PHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaHCO 3. Amino (− NH 2) content of PEI-modified PHEMA cryogel was determined as 82 mg PEI/g. Then, DNA was attached onto the PHEMA cryogel via amino groups (53.4 mg DNA/g cryogel). Anti-dsDNA-antibody concentration declined significantly from 780 IU/ml to 80 IU/ml with the time. The maximum anti-dsDNA-antibody adsorption amount was 70 × 10 3 IU/g. Anti-dsDNA-antibodies could be repeatedly adsorbed and eluted without noticeable loss in the anti-dsDNA-antibody adsorption amount.

Biosorption of toxic chromium from aqueous phase by lignin: mechanism, effect of other metal ions and salts

Surface reaction methodology was implicated in the optimization of hexavalent chromium removal onto lignin with respect to the process parameters. The influence of altering the conditions for removal of chromium(VI), for instance; solution pH, ionic strength, initial concentration, the dose of biosorbent, presence of other metals (Zn and Cu), presence of salts and biosorption–desorption studies, were investigated. It was found that the biosorption capacity of lignin depends on solution pH, with a maximum biosorption capacity for chromium at pH 2. Experimental equilibrium data were fitted to five different isotherm models by non-linear regression method, however, the biosorption equilibrium data were well interpreted by the Freundlich isotherm. The maximum biosorption capacities ( q max) obtained using Dubinin–Radushkevich and Khan isotherms for Cr(VI) biosorption are 31.6 and 29.1 mg/g, respectively. Biosorption showed pseudo second order rate kinetics at different initial concentrations of Cr(VI). The intraparticle diffusion study indicated that film diffusion may be involved in the current study. The percentage removal of chromium on lignin decreased significantly in the presence of NaHCO 3 and K 2P 2O 7 salts. Desorption data revealed that nearly 70% of the Cr(VI) adsorbed on lignin could be desorbed using 0.1 M NaOH. It was evident that the biosorption mechanism involves the attraction of both hexavalent chromium (anionic) and trivalent chromium (cationic) onto the surface of lignin.

Regioselective synthesis of pyridoquinolones and pyridocoumarins via molecular iodine-mediated 6-endo-dig electrophilic cylization

Angular-pyridoquinolone and pyridocoumarin derivatives have been efficiently synthesized in 60–95% yields by molecular iodine-mediated cyclization of easily available starting materials, 6-(N-propargyl)amino quinolone and coumarin derivatives, in the presence of NaHCO3. The reaction was carried out at room temperature.

Conventional and Microwave-Assisted Facile One-Pot Synthesis of N-Substituted Pyrrole-2,3,4,5-tetracarboxylates Under Neat Conditions

Highly substituted pyrroles 3a,f were prepared conveniently in a reaction of (dimethyl- and diethyl-)acethylenedicarboxylates 1a–b with N-(methyl- and aryl-) hydroxylamines 2a–d in the presence of NaHCO3 using both conventional heating and microwave irradiation. Excelent yields of the very pure products were isolated under solvent-free conditions both at classical as well as microwave heating.

ChemInform Abstract: Distinct Catalytic Effect of Micellar Solution of Sodium Dodecyl Sulfate (SDS) for One‐Pot Conversion of Alkyl Halides to Disulfides via an Odourless Process Using Thiourea and MnO2.

A novel one-pot odourless synthesis of symmetrical disulfides from their corresponding halides in aqueous media using thiourea and MnO2 in the presence of NaHCO3 or Na2CO3 catalyzed by micellar sol...

Antioxidant activity of unexplored indole derivatives: Synthesis and screening

The present study envisaged the development of novel antioxidant candidates using the indole scaffold. Several tryptophan and tryptamine derivatives were synthesized, in particular prenylated indole compounds, and their scavenging activity for reactive oxygen species (ROS) and reactive nitrogen species (RNS) was investigated. The library substitution pattern included several alkyl chains at positions N-1, C-2 of the indole nucleus, including prenyl and isopentyl chain, as well as different groups at the side chain (C-3) that allowed the investigation of a possible radical stabilization. The results obtained showed that tryptophan ( 8), tryptamine ( 9), N-phthaloyl tryptamine ( 5) and N-prenyl tryptophan ( 13) were the most active against peroxyl radical (ROO •) with activities higher than Trolox, which was used as control. The scavenging of hypochlorous acid (HOCl) was also evaluated and tryptophan ( 8) and tryptamine ( 9) showed IC 50 of 3.50 ± 0.4 and 6.00 ± 0.60 μM, respectively. Significant activity was also found for the N-prenyl tryptophan ( 13) with an IC 50 of 4.13 ± 0.17 μM and C-2 prenylated derivative ( 14), with 4.56 ± 0.48 μM. The studies were extended to RNS and best results were obtained against peroxynitrite anion (ONOO − ) in the presence of NaHCO 3. N-alkylated tryptophan ( 18) showed a high activity with an IC 50 of 14.0 ± 6.8 μM. The results show that the tested compounds are effective scavengers of ROS and RNS, and suggest that the radical stabilization is strongly dependent on the type of substituents on the indolic moiety and on their relative positions. In addition, the radical dissipation inside the indolic system is mandatory for the observed antioxidant activity.

ChemInform Abstract: Synthesis and Reactivity of 2H‐Pyran Moiety in [60]Fullerene Cage Skeleton.

The cyclopentadienyl type hexa-adduct C60(OOtBu)6 1 is readily converted into 2H-pyran containing fullerene derivative C60(O)(OOH)(OOtBu)5 2 in the presence of NaHCO3 and hydroquinone. In the proce...

Synthesis and Reactivity of 2H-Pyran Moiety in [60]Fullerene Cage Skeleton

The cyclopentadienyl type hexa-adduct C(60)(OOtBu)(6) 1 is readily converted into 2H-pyran containing fullerene derivative C(60)(O)(OOH)(OOtBu)(5) 2 in the presence of NaHCO(3) and hydroquinone. In the process, O-O bond of the tert-butylperoxo group on the central pentagon is cleaved, and the fullerene-bound oxygen radical inserts into a 5,6-junction to form the 2H-pyran moiety. Further reactions of 2 led to open-cage fullerenes with a nine-membered orifice and also both 3,4-dihydro-2H-pyran and 3,6-dihydro-2H-pyran containing fullerene derivatives. Mechanisms are proposed involving intramolecular S(N)2' and aza-Michael addition and ketal formation processes.

Distinct Catalytic Effect of Micellar Solution of Sodium Dodecyl Sulfate (SDS) for One-Pot Conversion of Alkyl Halides to Disulfides via an Odourless Process Using Thiourea and MnO2

Abstract A novel one-pot odourless synthesis of symmetrical disulfides from their corresponding halides in aqueous media using thiourea and MnO2 in the presence of NaHCO3 or Na2CO3 catalyzed by micellar solution of sodium dodecyl sulfate (SDS) is described. By this method, primary, allylic and benzylic halides were converted into their corresponding disulfides in high yields.

Copper(I) halide complexes with ethylenediaminium L0(H+)2, N,N,N′,N′-tetraallylethylenediaminium L4(H+)2, and N,N,N,N′,N′-pentaallylethylenediaminium L5(H+). Synthesis and crystal structures of the complexes [L0(H+)2]0.5CuCl2, [L0(H+)2]0.5CuBr1.67Cl0.33, [{L4(H+)2}0.5Cu2Cl3], and [L5(H+)Cu4Br6

Alkylation of ethylenediamine with allyl bromide in the presence of NaHCO3 in benzene-ethanol and acetone-ethanol gave N,N,N′,N′-tetraallylethylenediamine L4 and N,N,N,N′,N′-pentaallylethylenediaminium bromide (L5(H+)Br2), respectively. The ac electrochemical synthesis at copper wire electrodes in solutions of copper(II) halide and an appropriate ligand yielded single crystals of Cu(I) complexes with ethylenediaminium ([L0(H+)2]0.5CuCl2 (I) and [L0(H+)2]0.5CuBr1.67Cl0.33 (II)) and its N-allyl derivatives N,N,N′,N′-tetraallylethylenediaminium ([{L4(H+)2}0.5Cu2Cl3] (III)) and N,N,N,N′,N′-pentaallylethylenediaminium ([L5(H+)Cu4Br6] (IV)). The crystal structures of complexes I–IV were determined by X-ray diffraction. The isostructural crystals of complexes I and II are triclinic, space group P\( \bar 1 \), Z = 2. For I: a = 5.936(3), b = 6.387(3), c = 7.126(4) A, α = 67.82(4)°, β = 72.98(4)°, γ = 67.55(4)°, V = 227.7(2) A3. For IIa = 6.110(3), b = 6.657(3), c = 7.309(3) A, α = 68.40(3)°, β = 72.38(3)°, γ = 67.23(3)°, V = 250.4(2) A3. In structures I and II, the organic cations are between infinite anionic chains (Cu2−)n. The crystals of π-complex III are triclinic, space group P\( \bar 1 \), a = 6.851(4), b = 8.729(4), c = 9.960(4) A, α = 98.25(3)°, β = 102.29(3)°, γ = 107.30(3)°, V = 541.8(5) A3, Z = 2. In structure III, all the four allyl groups are π-coordinated by the metal atoms of four discrete anions Cu4Cl62−. The crystals of π-complex IV are monoclinic, space group C2/c, a = 15.228(5), b = 17.095(6), c = 20.182(6) A, β = 92.43(4)°, V = 5249(3) A3, Z = 8. Only two of five allyl groups at the same N atom are coordinated by copper(I) atoms. Structure IV contains a complex inorganic fragment of the formula (Cu4Br62−)n.

Synthesis of the C 5–C 30 fragment of cyclodidemniserinol trisulfate via I 2-mediated deprotection and ring closure tandem reaction

The marine natural product cyclodidemniserinol trisulfate displayed moderate HIV-1 integrase inhibitory activity. Its novel structure triggered our interest to synthesize it. In our total synthesis effort, the natural product was dissected into four fragments based on the rational retrosynthetic analysis. All four fragments were successfully prepared with orthogonal protection. And the assembly of fragment A and B furnished the C 5–C 30 key subunit by employing the I 2-mediated deprotection and intramolecular ketal formation tandem reaction in the presence of NaHCO 3 in MeCN. Our work provided flexible and practical approaches to synthesize and derive the 3,5,7-trisubstituted 6,8-dioxabicyclo [3.2.1] octane based analogs to search for new structure HIV-1 integrase inhibitors.

1-Vinylpyrrole-2-carbaldehyde oximes: synthesis, isomerization, and spectral properties

AbstractThe reaction of 1-vinylpyrrole-2-carbaldehydes with hydroxylamine hydrochloride in pyridine or ethanol in the presence of NaHCO 3 or NaOAc affords previously unknown 1-vinylpyrrole-2-carbaldehyde oximes in 95-99% yields. Isomerization of oximes from (E) to (Z) in the presence of strong acids and the spectral characteristics of the isomers were studied.Graphical Abstract[IMAGE]

Synthesis of (3RS)- and (3SR)-acetoxy-(3aRS,8bSR)-N-acetyl-5-methoxy-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indoles

Stereoisomeric 3-acetoxy-5-methoxy-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indoles differing by the configuration of the C3 atom were synthesized. The reaction of N-acetyl-6-(cyclopent-2-en-1-yl)-2-methoxyaniline with 50% hydrogen peroxide in the presence of Na2WO4-H3PO4 in AcOH gave (3RS,3aRS,8bSR)-N-acetyl-3-hydroxy-5-methoxy-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole which was converted into the corresponding 3-O-acetyl derivative by treatment with acetic anhydride in pyridine. N-Acetyl-6-(cyclopent-2-en-1-yl)-2-methoxyaniline reacted with iodine in methylene chloride in the presence of NaHCO3 to produce (3SR,3aRS,8bSR)-3-acetoxy-5-methoxy-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole which was subjected to acetylation at the nitrogen atom by reaction with acetic anhydride. The structure of (3RS,3aRS,8bSR)-N-acetyl-3-hydroxy-5-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole was proved by X-ray analysis.