Condensation Reaction Of Formaldehyde Research Articles

Aldol Condensation Reaction of Methyl Acetate and Formaldehyde Over Cesium Oxide Supported on Silica Gel: An Experimental and Theoretical Study

The catalytic performance of cesium oxide supported on three types of silica gel A-type (A-silica), B-type (B-silica) and C-type (C-silica) was tested for the aldol condensation of methyl acetate (Ma) and formaldehyde (FA) to methyl acrylate (MA). The catalysts were characterized using TEM, BET, XRD, FTIR, TG, XPS, and CO2-TPD and the reaction mechanisms were explored using DFT calculations. To obtain high selectivity of MA, appropriate amount of Cs loading is required since much higher loading of Cs leads to excessive decomposition of Ma and/or MA. On the Cs/silica, the Si–O–Cs species generated from the reaction of cesium oxide with silanol groups are the active sites as demonstrated by characterization and the DFT calculations. Silica gels with larger pore size and pore volume are preferred since these facilitate the contact of the reactants with active sites and provide higher capacity for accommodation of coke. As compared with Cs/SBA-15, Cs/B-silica seems more prospective for industrial application due to the lower cost of silica gel and even better performance.

Physical-chemical properties of chiral ionic liquids derived from the phenylethylamine enantiomers

Sixteen imidazolium based chiral ionic liquids (CILs) containing Br− and BF4− anions, derived from both enantiomers of phenylethylamine, were synthesized. The imidazole ring was constructed through a condensation reaction of formaldehyde, glyoxal and ammonium hydroxide in aqueous media resulting in a simple, versatile and environmentally friendly protocol. The CILs were synthesized with propyl, butyl, pentyl or hexyl alkyl substituents, which provoke a change of the physicochemical properties that were evaluated (glass transition temperature, thermal stability, optical rotation, ionic conductivity, electrochemical window and toxicity). The 1-alkyl-3-(1-phenylethyl) imidazolium tetrafluoroborate ([Cnpeim]BF4) family showed good thermal stability, large electrochemical window, low toxicity at moderate concentrations, and adequate viscosity. Therefore, these CILs are a good candidates to be used in asymmetric reactions and may be a viable alternative to organic solvents.

One-pot synthesis of 1,5,3-oxathiazepanes via the three-component condensation of primary amines, formaldehyde and 2-mercaptoethanol

The three-component condensation reaction of primary amines, formaldehyde and 2-mercaptoethanol using salts of transition and rare earth metals as catalysts was developed to obtain a new 7-membered heterocyclic structural building block, 1,5,3-oxathiazepanes, in good to excellent yields. The structure of the heterocyclic fragment was confirmed by NMR spectroscopy.

Synthesis and characterization of 1,3-bis(2-fluorophenyl)-5-pentyl-1,3,5-triazinane

A new triazinane derivative was obtained by condensation reaction of pentylamine, 2-fluoroaniline and formaldehyde (formalin) in basic solution to yield 1,3- bis (2-fluorophenyl)-5-pentyl-1,3,5-triazinane. The structure of the synthesized compound was characterized by spectroscopic methods: FT-IR, UV-Vis, 13 C, 19 F and 1 H NMR.

Copper(II) complex as a precursor for formation of cyano-bridged pentanuclear FeIII-CuII bimetallic assembly: Synthesis, characterization, crystal structure and antibacterial activity

[CuL(ClO4)2] (1) (L = 3,10-diisobutyl-1,3,5,8,10,12-hexaazacyclotetradecane) was synthesized by condensation reaction of ethylenediamine, formaldehyde and iso-butylamine in absolute ethanol. Characterization of 1 utilized various spectroscopic techniques, viz. elemental analysis, electrospray ionization-mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), diffuse reflectance spectroscopy (DRS) and thermogravimetric analysis (TGA). Based on these techniques, the structure of 1 was proposed as Cu(II) ion occupying octahedral geometry with four secondary amine nitrogens of the hexaazamacrocyclic ligand and two perchlorato anions. 1 was used as a precursor in the preparation of cyano-bridged bimetallic compound, [CuL]3[Fe(CN)6]2⋅5H2O (2), by reaction with K3[Fe(CN)6] in aqueous solution. Single-crystal X-ray analysis indicated that 2 crystallized in the monoclinic system with space group P21/n. The structure of 2 consisted of cyano-bridged FeIII-Cu II pentanuclear molecules having two [Fe(CN)6] 3− anions connected to three cis-[CuL] 2+ cations via two cis-cyanide ligands from each ferrate unit. In each of pentanuclear unit, the central [CuL] 2+ cation exhibited a distorted octahedral geometry while the other two units exhibited a distorted square pyramidal geometry. The room temperature magnetic moments of both complexes were measured to be 1.92 B.M. for 1 and 5.61 B.M. for 2. The in vitro antibacterial activity of 1 against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853 strains were studied and compared with standard drugs, which showed moderate antibacterial activity compared with Penicillin and Gentamicin. A copper mononuclear complex was synthesized, characterized with various techniques, and used as a precursor to synthesize a pentanuclear (FeIII-CuII) complex. The Xray structure of the new pentanuclear complex is reported. The precursor copper complex exhibited moderate antibacterial activity.

Synthesis and investigation of antimicrobial properties of pyrrolidine appended calix[4]arene

BackgroundCalixarenes are widely used macromolecules in supramolecular chemistry synthesized by simple phenol formaldehyde condensation reaction in the presence of base. This article describes the synthesis, antibacterial, and antifungal properties of calix[4]arene appended with pyrrolidine at the upper rim (CAP3).MethodsAntimicrobial activity of CAP3 was determined by Kirby-Bauer well agar diffusion method in Mueller-Hinton agar (MHA) medium of growth against Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 10231) and Streptococcus viridans (ATCC 12392), Candida albicans (ATCC 32333), Aspergillus niger (ATCC 16404), and Aspergillus flavus (ATCC 90906). Structure–activity relationship was also used to evaluate the active site of CAP3.ResultsBacterial strains have shown minimum inhibitory concentration (MIC) values in 1.17–2.34 mg/mL range; whereas, the fungal strains have shown MIC values at the range of 0.58-2.34 mg/mL. It is observed that CAP3 has excellent antifungal action for A. niger as well as antibacterial action for S. viridans having MIC values of 0.58 and 1.17 mg/mL, respectively. The SAR (structure–activity relationship) study of compound reveals that there is a significant antimicrobial activity shown by CAP3 probably due to the pyrrolidine substituents at phenyl rings of calix[4]arene.ConclusionsThe results indicate that CAP3 is an effective material against the microbial strains.

Novolac Phenol–Formaldehyde Oligomerization Kinetics Analysis

A kinetic model is developed and validated for the acid-catalyzed novolac phenol–formaldehyde condensation reaction used to produce the precursor to epoxy novolac. Novolac is widely used in adhesives, structural laminates, coatings, and castings because of high thermal stability and chemical resistance. Fitting of a kinetic model to experimental data for the novolac polymerization showed that formaldehyde and methylol “Q” species do react with significantly different rates. However, in disagreement with previous literature modeling efforts, ortho and para sites react with similar rates, as do internal and external sites. This finding led to being able to account explicitly for the reactivity of available sites for each molecule, removing the need for site balances. This updated model reduced calculated error and allowed determination of the activation energy for novolac polymerization of 79.5 ± 0.4 kJ/mol.

Task-specific Ionic Liquid-mediated Facile Synthesis of 1,3,5-Triaryltriazines by Cyclotrimerization of Imines and Their Biological Evaluation

Abstract A highly efficient method for the synthesis of fluorinated 1,3,5-triaryltriazine derivatives is developed by the condensation reaction of aromatic amines and formaldehyde followed by spontaneous cyclotrimerization using task-specific 1,1,3,3-tetramethylguanidine trifluoroacetate [TMG][Tfa] ionic liquid as a environmentally benign solvent in excellent yields at room temperature. The synthesized compounds were subjected for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv strain using the Löwenstein–Jensen medium.

Synthesis of melamine-formaldehyde resin functionalised with sulphonic groups and its catalytic activities

AbstractSpherical melamine-formaldehyde resin (MFR) particles were synthesised using the condensation reaction of melamine and formaldehyde with PEG-2000 as an additive. After thermal treatment at 200°C and then sulphonation by chlorosulphuric acid, an MFR-supported strong acid catalyst (SMFR) was prepared with an acidity of 3.23 mmol g−1. This new acid catalyst was evaluated in the reactions of esterification and acetalisation, with the results indicating that this novel acid catalyst was highly efficient in the traditional acid-catalysed reaction. Its high activity, stability and reusability give it great potential for “green” chemical processes.

Synthesis and Performance of a Multi‐Purpose Gemini Precursor and the Derivative Alkylaryl Sulfonate Gemini Surfactants

AbstractThe phenol–formaldehyde condensation reaction to synthesize a gemini precursor was renewed by using high efficient and environmentally benign resin catalysts instead of protonic acids, and the conversion, yield and selectivity of the reaction were all upgraded from the 60 % by the traditional way to over 90 % by the new way. Three alkylaryl sulfonate gemini surfactants were derived from the above gemini precursor by O‐methylation, sulfonation and neutralization, that is, sodium salt of sulfonated bis(2‐hydroxy‐5‐nonylphenyl)methane (SBHNM), sodium salt of sulfonated bis(2‐hydroxy‐5‐dodecylphenyl)methane (SBHDM) and sodium salt of sulfonated bis(2‐methoxy‐5‐nonylphenyl)methane (SBMNM). And their performances in aqueous solution were further investigated. The results show that the three gemini surfactants exhibit higher effectiveness and efficiency in surface tension reduction than a monomeric reference surfactant sodium dodecylbenzene sulfonate (SDBS). Furthermore their critical micelle concentration values are at least one order of magnitude lower than that of SDBS. It is also shown that O‐methylation of the hydroxyl group in the gemini precursor is effective at improving the surface activity of the gemini surfactants, such as efficiency in surface tension reduction, foam stability and calcium stability. It is suggested that the synthesized hydrophobic skeleton could be a multi‐purpose gemini precursor from which various gemini surfactants could be derived by further hydrophobic or hydrophilic modification.

Synthesis and characterization of valonea tannin resin and its interaction with palladium (II), rhodium (III) chloro complexes

Valonea tannin (TA) and formaldehyde condensation reaction was carried out under alkaline condition to prepare the valonea tannin–formaldehyde resol resin (TAR). Obtained resin was used as adsorbent for recovery of palladium (II) and rhodium (III) ions from chloride-containing solutions. This kind of recovery was very simple and useful for generating little secondary wastes. Interaction of adsorption also was investigated: Chloropalladium (II) species were reduced to Pd(0), while hydroxyl groups of TAR were oxidized during the adsorption. Proposed adsorption of the aquachlororhodium (III) species mostly takes place via ligand exchange mechanism. TAR, Rh-adsorbed TAR, and Pd-adsorbed TAR were characterized by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction spectroscopy, and Fourier transform infrared–attenuated total reflection spectroscopy.

Synthesis of large surface area carbon xerogels for electrochemical double layer capacitors

A resorcinol–formaldehyde (R–F) condensation reaction catalyzed by acetic acid (C) is employed to prepare carbon xerogels for electrochemical double layer capacitors. The samples are fabricated with an R:F ratio of 1:2 and R:C ratio of 10:1, followed by solvent exchange, pyrolysis, and carbon dioxide activation. The solvent exchange allows negligible structure contraction upon drying, and after pyrolysis and carbon dioxide treatment, we are able to produce porous carbons with a surface area of 3419 m2 g−1. Image from scanning electron microscope reveals an interconnected foam-like structure and BET confirms the presence of excessive micro- and mesopores. Electrochemical analysis including cyclic voltammetry (CV), current reversal chronopotentiometry (CRC), and impedance spectroscopy are conducted using a titanium cavity electrode so relevant capacitive characteristics and kinetic parameters could be determined. Both CV and CRC results indicate specific capacitances and life time behaviors that are comparable or even better than those of Black Pearl 2000. For example, the specific capacitance is 324.8 F g−1 in 0.5 M H2SO4 aqueous solution at ±1 A g−1 for potential window of 0–1 V. In contrast, sample without carbon dioxide activation displays a similar morphology but its surface area and specific capacitance are reduced considerably to 449 m2 g−1 and 34.7 F g−1, respectively.

Synthesis and Characterization of Pyrogallol-Formaldehyde Nano Resin and Its Usage as an Adsorbent

A pyrogallol (PG) and formaldehyde condensation reaction was carried out under alkaline conditions to prepare the pyrogallol–formaldehyde resol resin (PGNR). Polymerization was performed to establish the nano resin formation. Obtained nano resin was used as an adsorbent for recovery of rhodium(III) ions from chloride-containing solutions. This kind of recovery was very simple and useful for generating little secondary wastes. The interaction of adsorption also was investigated: The proposed adsorption of the aquachlororhodium(III) species mostly takes place via a ligand exchange mechanism. PGNR and Rh-adsorbed PGNR were characterized by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction spectroscopy, and Fourier transform infrared–attenuated total reflection spectroscopy. By utilizing such characteristics of polyphenol resin, PGNR can be applied to recover Rh(III) efficiently and simply with low cost.

Synthesis and Characterization of Gallic Acid Resin and Its Interaction with Palladium(II), Rhodium(III) Chloro Complexes

Gallic acid (GA) and formaldehyde condensation reaction was carried out under alkaline condition to prepare the gallic acid–formaldehyde resol resin (GAR). Obtained resin was used as adsorbent for recovery of palladium(II) and rhodium(III) ions from chloride-containing solutions. This kind of recovery was very simple and useful for generating little secondary wastes. Interaction of adsorption also was investigated: Chloropalladium(II) species were reduced to Pd(0), while hydroxyl groups of GAR were oxidized during the adsorption. Proposed adsorption of the aquachlororhodium(III) species mostly takes place via ligand exchange mechanism. GAR, Rh-adsorbed GAR, and Pd-adsorbed GAR were characterized by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction spectroscopy, and Fourier transform infrared–attenuated total reflection spectroscopy.

Carbazole modified ketonic resins

PurposeThe purpose of this paper is to report the synthesis of resins having conducting and fluorescence properties, with carbazole and oligocarbazole with a one step method of in situ modification of ketonic resin. Cyclohexanone‐formaldehyde (CFR), and acetophenone‐formaldehyde (AFR) resins were in situ modified with carbazole in the presence of sodium hydroxide.Design/methodology/approachCarbazole modified ketonic resins were synthesised by the condensation reaction of Cz, formaldehyde and ketone. Oligo carbazole was synthesised by redox reaction of carbazole and ceric ammonium nitrate (CAN). Then, for the in situ modification of oligo carbazole modified ketonic resin, reaction mixture of oligocarbazole carbazole was added to the cyclohexanone/formaldehyde solution.FindingsThe carbazole modified cyclohexanone‐formaldehyde and acetophenone formaldehyde resins have conductivity values of 10−5‐10−6 S/cm and may be considered as semi‐conductive ketonic resins. These new carbazole modified ketonic resins (CCzFR, ACzFR) have fluorescence properties.Research limitations/implicationsThis study focused on obtaining a conductive and fluorescence resin using a carbazole monomer which is an insulator.Practical implicationsThis study provides technical information for the synthesis of fluorescence comonomer.Originality/valueNew CCzFR, ACzFR comonomers were synthesised. These comonomers have higher Tm values than CFR and AFR alone and also have fluorescence property.

Monofunctional benzoxazine from cardanol for bio-composite applications

In this study, a monofunctional benzoxazine monomer was synthesized by condensation reaction of aniline and formaldehyde with cardanol, a by product of cashew nut shell liquid (CNSL). The monomer was characterized by FTIR and 1H NMR spectral analysis. Curing characteristics were studied by differential scanning calorimeter. The exothermic peak associated with curing was observed from 230 °C to 291 °C with a peak maximum of 272 °C. Adding a small percentage of cardanol as phenolic initiator reduced the onset of cure as well as peak maximum temperature due to accelerated curing. Thermo gravimetric analysis indicated a peak decomposition temperature of 432 °C and a char yield of 24% at 800 °C. The viscoelastic properties of the neat cardanol benzoxazine, its jute fiber composite and the acrylonitrile modified jute fiber composites were studied with dynamic mechanical thermal analyzer (DMTA). The storage modulus ( E′) value increased with fiber loading and showed a higher value for treated composite indicating an increase in interaction between fiber and resin matrix. On the other hand, the tan δ which is associated with glass transition, shifted to lower value compared to neat resin with incorporation of jute fibers.

Synthesis of Novel Chiral Thioether Ligands Containing Imidazole Rings Based on Natural Amino Acids

Using commercially available natural amino acids (L-Val, L-Leu, L-Phe) as chiral precursors, a series of N-substituted imidazole derivatives containing chiral groups was synthesized from the condensation reaction of amino acids, formaldehyde, glyoxal, and ammonia. Through esterification, reduction, chlorination, and subsequent substitution by thiols, chiral thioethers containing imidazole rings were synthesized, and the synthetic conditions were optimized. All the intermediates and the final products were characterized by NMR, ESI MS, HR MS, and IR.

A study on the kinetics of condensation reaction of cardanol and formaldehyde, part I

AbstractNovolac resins having cardanol‐to‐formaldehyde mole ratios of 1:0.4, 1:0.5, and 1:0.6 were prepared by using aromatic sulphonic acid as the catalyst at four different temperatures ranging between 90°C and 120°C, with an interval of 10°C. Free formaldehyde and free phenol contents were determined at regular time intervals to check the completion of the reaction. The synthesized novolacs were characterized by Fourier‐transform infrared spectroscopic analysis, nuclear magnetic resonance, and gel permeation chromatography. The reaction between cardanol and formaldehyde was found to follow second‐order kinetics. The overall rate constant (k) increased with the increase of temperature. On the basis of the value of k, various other activation parameters such as activation energy (Ea), change in enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) of the reaction were also evaluated. It was found that the condensation reaction of cardanol and formaldehyde with aromatic sulphonic acid was nonspontaneous and irreversible. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 559–572, 2009

Studies on the process variables of the condensation reaction of cardanol and formaldehyde by response surface methodology

Different types of cardanol-based novolac-type phenolic resins are produced under a wide range of operating conditions for the application in the resin producing industries. Different operating conditions employed for the production of such resins result in different extent of conversion. In order to understand the system behavior, mathematical relationship between the process variables and the extent of conversion was established by employing the ‘Response surface methodology’. Geometrical representation of the mathematical models in three-dimensional surface plots served as a good aid in understanding the behaviour of reaction under different operating conditions. The maximum extent of conversion of the condensation reaction of cardanol and formaldehyde was found to be 93.0 percent at optimum sets of condition of reaction temperature, time, catalyst concentration and pH of the reaction mixture. All the predicted values for optimum process conditions were in good agreement with experimental data.

A study on sisal fiber-reinforced benzoxazine/epoxy copolymer based on diamine-based benzoxazine

A diamine-based benzoxazine monomer has been synthesized via the Mannich condensation reaction of ethylenediamine, phenol and formaldehyde. The effect of solvent was investigated. The chemical structure and thermal properties of the diamine-based benzoxazine were characterized by FT-IR, NMR, DSC and TGA. Sisal fibers are incorporated in a mixture of benzoxazine and bisphenol-A type epoxy resins to form a unidirectionally reinforced composite. The effects of varying fiber contents and matrix composition on the mechanical properties of the composites are studied.