Reactions Of Vanillin Research Articles

Synthesis and characterization of 4-hydroxy-3-((2-hydroxy-3-methoxybenzylidene)amino)benzene-sulfonic acid and its metal complexes and their antimicrobial activity

Schiff base was obtained from the reaction of vanillin with 3-amino-4-hydroxybenzenesulfonic acid. Metal complexes were synthesized using (Ni(NO3)2, Co(NO3)2, Mn(NO3)2, Cu(NO3)2, Zn(NO3)2) metal salts and the structures of the compounds were elucidated by spectroscopic methods. The structures of the metal complexes were also characterized by elemental analysis, FT-IR, thermogravimetric analysis and magnetic susceptibility analysis and their antimicrobial activities were investigated. The antimicrobial activities of the obtained coordination compounds were investigated against three Gram-positive (Bacillus subtilis ATCC 6633; Staphylococcus aureus ATCC 25923; Enterococcus faecalis ATCC 29212) three Gram-negative bacterial (Escherichia coli ATCC 25922; Klebsiella pneumonia ATCC 70060; Pseudomonas aeruginosa ATCC 27853) strains and two fungal (Aspergillus niger ATCC 16404; Candida albicans ATCC 1023) strains, and the minimum inhibitory concentration (MIC) values were determined. According to the MIC values, the SCNi complex exhibited the highest antimicrobial activity, while the SCCu complex showed the lowest.

Effect of imine-containing phenolic hardeners with different chain lengths and epoxy functionalities on thermal, mechanical, and healing properties of bio-based epoxy vitrimers

Mixtures of polyglycerol polyglycidyl ether (PGPE) and poly(ethylene glycol) diglycidyl ether (PEGDGE) with different molar ratios were cured with imine-containing phenolic hardeners prepared by the reactions of vanillin with ethylene glycol bis(3-aminopropyl) ether, diethylene glycol bis(3-aminopropyl) ether, and a polyetheramine (JEFFAMINE® ED-600) to produce bio-based epoxy cured products. Fourier-transform infrared spectroscopy (FT-IR) of the cured products revealed that the curing reaction of the epoxy and phenolic hydroxy groups was almost complete. The cross-linking density, glass transition temperature, and mechanical strength of the cured products decreased with decreasing the PGPE/PEGDGE ratio and increasing the oligoalkyleneoxy chain length of the phenolic hardeners. All cured products were healed three times at 100 °C under 2 MPa for 2 h. The healing efficiency, in terms of tensile strength, increased with decreasing PGPE/PEGDGE ratio and increasing oligoalkyleneoxy chain length. The polyetheramine-based cured product with the lowest PGPE/PEGDGE ratio exhibited the highest healing efficiency (94–97%), which only slightly decreased following repeated healing treatments.

Colorimetric surface lipid quantification in Drosophila.

Insects are covered with free neutral cuticular hydrocarbons (CHC) that may be linear, branched, and unsaturated and vary in their chain length. The CHC composition is species-specific and contributes to the adaptation of the animal to its ecological niche. Commonly, CHCs contribute substantially to the inward and outward barrier function of the cuticle and serve pheromonal communication. They are generally determined by gas-chromatography, a time-consuming method requiring detailed expertize, but it is not available in many laboratories. Here, we report on the establishment of a colorimetric method allowing semi-quantitative determination of unsaturated CHCs in Drosophila flies. This method is based on the in vitro reaction of vanillin with double bounds in lipid molecules in an acidic solution to generate a reddish color. We found a robust correlation between gas chromatographic and vanillin-colorimetric data on unsaturated CHCs amounts in single flies. As the role of unsaturated CHCs in the performance of insects in their environment is only partly understood, we think that this novel method would allow fast and broad analyses of this type of CHCs in insects both in the field and in laboratories and thereby contribute to a substantial improvement in the investigation of this matter.

Synthesis, characterization, and electronic structure of bioactive vanillin based fluorescent Schiff bases

This manuscript presents a comprehensive investigation into the Synthesis, characterization, and molecular properties of a novel compound, (E)-2-methoxy-4-((phenylimino)methyl)phenol, referred to as ANVA. The synthesis procedure involved the reaction of vanillin and aniline, which resulted in the formation of ANVA. Various analytical techniques, including FTIR, fluorescence, UV–Vis, 1HNMR, and 13CNMR, were employed to characterize the compound's structural and spectral properties. We conducted theoretical investigations using DFT/B3LYP/cc-pVDZ techniques to gain insights into the compound's electronic structure, stability, and reactivity. Molecular Electrostatic Potential (MEP) analysis elucidated the molecule's polarity and revealed potential nucleophilic attack sites. Mulliken population analysis showed the distribution of electrical charges among atoms, influencing various chemical properties. Quantum Theory of Atoms in Molecules (QTAIM) analysis, including ELF and LOL, provided a deeper understanding of electron localization and delocalization, shedding light on covalent bonds and molecular stability. The study also explored non-covalent interactions through Reduced Density Gradient (RDG) analysis, indicating weak and strong interactions within the compound. Molecular docking studies were performed to assess the potential biological activity of ANVA, yielding significant insights into its interaction with specific protein targets.

Design of advanced and highly effective partially bio-energetic polybenzoxazines as the next generation of reactive structure materials

ABSTRACT In this study, a new class of energetic green benzoxazine polymers is introduced based on vanillin, as a renewable reactant. The newly developed monomers were afforded by the reaction of vanillin with exploshores groups bearing compounds, namely the 2,4 dinitrophenylhydrazine and the para-nitroaniline, respectively, following the typical Mannich reaction. The chemical structure and the formation of the oxazine ring of both monomers were confirmed by 1H and 13C NMR, FTIR, and elemental analysis. The ring opening polymerization mechanism was investigated by FTIR and DSC-TGA analyses. The energetic performances, as well as the physicochemical properties, were studied by a bomb calorimeter, deflagration tester, and electronic densimeter. Overall, both polymers showed promising energetic performances with deflagration temperatures of about 275 and 261°C for the 2,4 dinitrophenylhydrazine and para-nitroaniline-based polybenzoxazines, respectively. The thermal analysis results highlighted that these polymers can be effectively used as reactive structure materials (RSMs) owing to their combination of high thermal stability above operational temperatures and remarkable energetic performances.

Walatimine (Vanillyl Butyl Imine): A New Ketimine from Schiff Base Synthesis and Evaluation of its Antioxidant, Antibacterial and Antifungal Properties

Background of study: Vanillin is a white crystalline compound which is a phenolic aldehyde with a balsamic flavour. It is widely obtained from vanilla bean-pods amongst very many other sources. This compound and some of its derivatives possess diverse activities including anticancer, anti- inflammatory, antioxidant, antibacterial and antifungal amongst others. Hence, the import of this study. Objectives: The growing concerns about the deleterious actions of free radical oxygenated species (FROS) in the human body have become a huge concern to the scientific world. These chemical species continually devastate the human cells, tissues and organs leading to different pathophysiological conditions and neurodegenerative disorders. Also, the noticeable microbial resistance to antibiotics and antifungal drugs have prompted the search for lead compound(s) with the aim of chemically modifying its/their molecular structure(s) or synthesizing other compounds from reactions involving them such as Schiff base synthesis. The search for novel pharmaceutically active compounds with the aim of ameliorating these conditions led to the choice of vanillin. Methodology: Vanillin was subjected to the Schiff base synthesis. It was reacted separately with amines (aromatic and aliphatic amine) leading to the bases in the presence of acid. The melting points, refractive indices and optical rotations of the vanillin and the Schiff bases were obtained. The antioxidant activity (IC50) of the lead compound and bases was determined employing the DPPH (2, 2-diphenyl-1-picrylhydrazyl hydrate) bench-top assay test. Comparison of the obtained antioxidant activities was done to determine if any improvements could be noticed in the synthesized bases. Also, the agar-in-hole diffusion method was adopted for screening vanillin and the synthesized bases against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeriginosa and Candida albicans for antibacterial and antifungal activities respectively. Results: The identities of the synthesized Schiff bases have been revealed to be vanillyl butyl imine (W) a new ketimine referred to by the trivial name- Walatimine and vanillin-2,4-dinitrophenyl hydrazone (Vdnp) respectivelyusing a combination of physico-chemical determinations and IR spectral technique. Vanillin and (W) demonstrated marginal antioxidant activity of IC50 of 0.52 and 0.50 μg/mL respectively while Vdnp gave a remarkably significant IC50 of 0.48 and which compare favourably with 0.46 μg/mL elicited by Vitamin C (a standard antioxidant drug). The antibacterial and antifungal activities elicited by both W and Vdnp were concentration dependent. Furthermore, Vdnp was comparably more bacteriostatic than W against the test bacteria though it was inactive against Ps. aeriginosa. However, vanillyl butyl imine (W) was slightly more anti-candidal against C. albicans than vanillin-2,4-dinitrophenyl hydrazone (Vdnp). Conclusion: The results from this study indicate that vanillin-2,4- dinitrophenyl hydrazone (Vdnp) obtained from the condensation reaction of vanillin and an aromatic amine affords a comparably better antioxidant activity than W obtained from vanillin reacting with an aliphatic amine. Both W and Vdnp demonstrated remarkable antibacterial and antifungal activities hence, these two synthesized Schiff bases can be lead candidate compounds in the search for newer and more efficacious antioxidant and antimicrobial agents and in further structural activity relationship studies (SARS) and as well as in formulation studies in drug development.

Fabrication of a transparent, flame retardant, and antimicrobial epoxy resin by a novel phosphorus-containing Schiff base molecule

A flame retardant DPPVA was synthesized through a Schiff-base reaction of vanillin, 3,5-diamino-1,2,4-triazole, and diphenylphosphinyl chloride, which was used to improve the thermal stability, flame retardancy, and antibacterial activity of the cured epoxy resin (EP). The EP/4% DPPVA sample looked yellow, but it was still transparent, and it passed the V-0 rating with a limit oxygen index (LOI) of 34.5%. The presence of 4wt% DPPVA in EP decreased the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) by 32.5%, 25.2%, and 29.3%, respectively. Compared with that of the control EP, the char residue was increased to 14.9wt% from 9.6wt%. In TGA the max mass loss rate of the EP/4% DPPVA sample was reduced to 0.86%/ °C from 1.75%/ °C of the control sample, which means the pyrolysis of EP was slowed down by DPPVA. The EP/4% DPPVA sample exhibited effective repellence to E. coli and S. aureus. The addition of 4% DPPVA to EP decreased the impact strength to 8.5 kJ/m2 from 9.9 kJ/m2, which was acceptable for many industrial scenarios. This work provided a potential strategy with an easy process for manufacturing flame retardant, antibacterial and transparent EP composites.

Reduced Graphene Oxide and Poly (phenylalanine) Composite Modified Electrode for the Electrochemical Determination of Vanillin

In this study, a simple, low cost and stable electrochemical sensor for vanillin is reported based on glassy carbon electrode (GCE) modified with poly (phenylalanine) and electrochemically reduced graphene oxide (ERGO) composite (poly (phenylalanine)/ERGO/GCE). The surface structure of the bare and modified electrodes was characterized by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The electrochemical behavior of vanillin at phenylalanine)/ERGO/GCE) was also studied by CV. Poly (phenylalanine)/ERGO/GCE) exhibited high electrocatalytic activity for the electrochemical oxidation of vanillin due to the synergetic effects of poly (phenylalanine) and ERGO. From linear sweep voltammetry (LSV) study, the electrode reaction of vanillin is adsorption-controlled process. Furthermore, several electrochemical parameters such as number of electrons transferred (n = 2), number of protons transferred (H+ = 2), electron transfer coefficient (α = 0.66) and surface concentration of vanillin (Ґ = 0.32 nmol cm−2) were calculated. SWV was used for quantitative determination of vanillin at phenylalanine)/ERGO/GCE). Under the optimum conditions, the oxidation peak current of vanillin increased linearly with its concentration in the range 0.25–120 μM with a low detection limit of 0.025 μM. The developed sensor was successfully applied for the determination of vanillin in food and soft drink samples.

Synthesis and characterization of novel acyl hydrazones derived from vanillin as potential aldose reductase inhibitors.

In the polyol pathway, aldose reductase (AR) catalyzes the formation of sorbitol from glucose. In order to detoxify some dangerous aldehydes, AR is essential. However, due to the effects of the active polyol pathway, AR overexpression in the hyperglycemic state leads to microvascular and macrovascular diabetic problems. As a result, AR inhibition has been recognized as a potential treatment for issues linked to diabetes and has been studied by numerous researchers worldwide. In the present study, a series of acyl hydrazones were obtained from the reaction of vanillin derivatized with acyl groups and phenolic Mannich bases with hydrazides containing pharmacological groups such as morpholine, piperazine, and tetrahydroisoquinoline. The resulting 21 novel acyl hydrazone compounds were investigated as an inhibitor of the AR enzyme. All the novel acyl hydrazones derived from vanillin demonstrated activity in nanomolar levels as AR inhibitors with IC50 and KI values in the range of 94.21 ± 2.33 to 430.00 ± 2.33nM and 49.22 ± 3.64 to 897.20 ± 43.63nM, respectively. Compounds 11c and 10b against AR enzyme activity were identified as highly potent inhibitors and showed 17.38 and 10.78-fold more effectiveness than standard drug epalrestat. The synthesized molecules' absorption, distribution, metabolism, and excretion (ADME) effects were also assessed. The probable-binding mechanisms of these inhibitors against AR were investigated using molecular-docking simulations.

Photocurable extended vanillin-based resin for mechanically and chemically recyclable, self-healable and digital light processing 3D printable thermosets

A vanillin-based photocurable resin was designed for circularity by incorporation of imine functionalities through a Schiff-base reaction between the aldehyde function of vanillin and amino group of ethylene diamine. Sufficient flexibility was provided by a short aliphatic segment introduced by reaction of vanillin with ethylene carbonate, while photocurability was obtained by subsequent methacrylation. The cured thermoset had good solvent resistance, relatively high glass transition temperature (∼75 °C) and good thermal stability with an onset of degradation above 300 °C. Due to the crosslinked structure and imine linkages, the thermoset expressed malleability, self-healing and thermal reprocessability. Furthermore, it could be chemically recycled by immersing in ethylene diamine, which activated transimination. The obtained oligomeric product with amine-terminal groups could be utilized for production of new thermoset films. Tensile testing illustrated similar elastic modulus for mechanically and chemically recycled thermosets, while a slight increase was observed for the self-healed samples, ascribable to a completion of the curing during the post-processing. At the same time elongation and stress at break slightly decreased. Finally, the suitability of the resin for the production of 3D objects by means of digital light processing (DLP) 3D printing was demonstrated.

Mechanistic Kinetic Analysis of Fast Pyrolysis of Vanillin to Primary Phenols

Vanillin is a major fine chemical in the flavoring industry and one of the pyrolysates from lignin. In order to understand the primary decomposition pathways of vanillin, analytical fast pyrolysis experiments were performed in the temperature range of 500°C–650°C, and the primary pyrolysates were quantified. The proposed pyrolysis chemistry involves 31 elementary reactions of 23 species. Thermodynamic and kinetic analyses were performed using quantum chemical density functional theory calculations. Reaction pathways for the formation of three major phenolics, viz., guaiacol, 5-formylsalicyaldehyde and 4-hydroxybenzaldehyde, that accounted for ∼80 wt% yield at 650°C, were proposed. Based on the bond dissociation energies (BDEs) of homolytic cleavage of the various bonds in vanillin, the primary reaction is shown to involve the cleavage of O–CH3 bond whose BDE is 61.4 kcal mol−1. New bimolecular reactions such as ipso-addition involving the reaction of vanillin with hydrogen and methyl radicals were proposed. The generation of 4-hydroxy methoxybenzyl radical was found to be vital for the formation of guaiacol, while 4-hydroxy-3-(λ3-methoxyl) benzaldehyde radical was the key intermediate for the formation of 5-formylsalicyaldehyde. Multiple pathways for the formation of guaiacol, 5-formylsalicyaldehyde, catechol and 4-hydroxybenzaldehyde were evaluated. In order to track the time evolution of vanillin and its major pyrolysates, a detailed kinetic model was developed using the elementary reactions and their Arrhenius rate parameters. Based on the kinetic model, it is inferred that the timescale of fast pyrolysis is captured well by the model.

Synthesis and properties of a novel autocatalytic phthalonitrile monomer and its copolymerization with multi‐functional fluorene‐based benzoxazine monomers

AbstractA novel autocatalytic phthalonitrile monomer [4,4′‐(((((oxy‐bis [4,1‐phenylene]) bis (azanediyl)) bis (methylene)) bis (2‐methoxy‐4,1‐phenylene)) bis (oxy)) diphthalonitrile, OPD] is obtained by nucleophilic substitution of 4‐nitro‐phthalonitrile and bisphenol compound [4,4′‐(((oxy bis [4,1‐phenylene]) bis (azanylylidene)) bis (methanylylidene)) bis (2‐methoxyphenol)]. Bisphenol compound is a reductant with secondary amine groups of Schiff base derived from the reaction of vanillin and 4,4′‐diaminodiphenylether. The OPD monomer has a self‐catalytic polymerizing reaction. OPD monomer has good processability, and the processing window was 130°C. Moreover, OPD polymer [poly(OPD)] shows higher glass‐transition temperature (345°C). The 5% and 10% thermal decomposition temperatures of poly(OPD) and char yield at 800°C are 407, 451°C, and 69%, respectively. To further improve the properties of poly(OPD), the OPD monomer was modified by multi‐functional fluorene‐based benzoxazine monomers (MFFB) due to their excellent reaction activities. The results showed that OPD/MFFB systems had high reaction activities. The similar thermal stabilities between OPD and MFFB can give stable and excellent thermal stability to the poly(OPD/MFFB). Compared with poly(OPD), the Tg values of poly(OPD/MFFB) were significantly increased, and their stiffness values were reduced. The tensile, flexural, and impact properties for poly(OPD/MFFB) were improved significantly.

Synthesis and properties of novel self-catalytic phthalonitrile monomers with aliphatic chain and their copolymerization with multi-functional fluorene-based benzoxazine monomers

A novel series of self-catalytic phthalonitrile monomers with aliphatic segments (BPAA) were synthesized via nitro nucleophilic substitution reaction of bisphenol compound and 4-nitrophthalonitrile. Bisphenol compound was reductant with secondary amine groups of Schiff base derived from the reaction of vanillin and one of the aliphatic diamine such as 1,2-ethylenediamine, 1,3-propane diamine, and 1,6-hexamethylenediamine. The curing reaction of BPAA monomers can be carried out without any catalyst. BPAA monomers showed excellent processing properties. Moreover, BPAA polymers (poly(BAPP)) showed superior thermal stabilities and higher glass-transition temperatures (Tg) (302–317 °C). The 5% thermal decomposition temperatures (T5) of poly(BAPP) and char yield (Yc) at 800 °C under nitrogen atmosphere were 352.5–410.5 °C and 61.3–66.8%, respectively. To further improve the thermal stability of poly(BAPP), BPAA monomers were modified by multi-functional fluorene-based benzoxazine monomers (MFFB) due to their excellent reaction activities. The results showed that BAPP/MFFB systems had high reaction activities and good processing behaviors. The similar thermal stabilities between BAPP and MFFB can give stable and excellent thermal stability (T5 ≥ 378 °C) to the poly(BAPP/MFFB) systems.

Theoretical investigation on the mechanisms and kinetics of OH/NO3-initiated atmospheric oxidation of vanillin and vanillic acid

Vanillin and vanillic acid are two kinds of lignin pyrolysis products that are generated by biomass combustion. The gas-phase oxidation mechanisms of vanillin and vanillic acid initiated by OH/NO3 radicals were investigated by using density functional theory (DFT) at M06–2X/6-311+G(3df,2p)//M06–2X/6-311+G(d,p) level. The initial reactions of vanillin and vanillic acid with OH/NO3 radicals can be divided into two patterns: OH/NO3 addition and H-atom abstraction. For vanillin reacted with OH radical, the OH addition mainly occurs at C2-position to produce highly chemically activated intermediate (IM2). The oxidation products 3,4-dihydroxy benzaldehyde, malealdehyde, methyl hydrogen oxalate, methylenemalonaldehyde, carbonyl and carbonyl compounds are formed by the subsequent reactions of IM2. H-atom abstracting from aldehyde group occurs more easily than from the other positions. In addition, vanillin reacting with NO3 radicals principally proceeds via NO3-addition at C1 sites and H-atom abstracting from OH group (C1) to generate HNO3. The primary reaction mechanisms of vanillic acid with OH/NO3 radicals were similar to vanillin. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory was performed to calculate the rate constants of the significant elementary reactions. The total rate constants for OH-initiated oxidation of vanillin and vanillic acid are 5.72 × 10−12 and 5.40 × 10−12 cm3 molecule−1 s−1 at 298 K and 1 atm. The atmospheric lifetimes were predicted to be 48.56 h and 51.44 h, respectively. As a supplement, the kinetic calculations of NO3 radicals with two reactants were also discussed. This work investigates the atmospheric oxidation processes of vanillin and vanillic acid, and hopes to provide useful information for further experimental research.

Colorimetric Amine Detection by Vanillin-Hydrazone Derivatives during Chicken Meat Spoilage

Two vanillin-hydrazone compounds as the colorimetric amine detection during chicken meat spoilage are described. Two hydrazone compounds (1 and 2) have been synthesized from the condensation reaction of vanillin with phenylhydrazine and 2,4-dinitrophenylhydrazine. Their properties for colorimetric recognition of amine were determined by the naked eye and UV-vis spectra. Their properties as amine indicators were investigated toward primary amine: butylamine (BA); secondary amine: dimethylamine (DMA), diethylamine (DEA); tertiary amine: triethylamine (TEA), and also ammonia (Amm). The hydrazone 1 in DMSO showed no significant color changes (colorless) after the addition of amines solution. Hydrazone 2 (5×10-5 M in DMSO) showed color changes from yellow to violet in the presence of ammonia, DEA and BA, to reddish-violet for DMA, and light brown after addition of TEA solutions. The colorimetric amine detection by vanillin-hydrazone 2 could recognize the real amine during chicken meat spoilage from yellow to light brown after 24 h storage at room temperature.

Vanillin conversion by aldol condensation using hydrotalcite Mg-Al and modified-Y zeolite as heterogeneous catalysts

Mg-Alhydrotalcite, MgO-Al2O3 mixed oxides and modified-Y zeolite (sulfated Y zeolite and copper ion-exchanged Y zeolite) were prepared and characterized by XRD, EDX and XRF techniques. These materials were used as heterogeneous catalysts in aldol condensation of vanillin and acetone.The obtained results showed that the heterogeneous acid catalysts as modified-Y zeolites were more effective than the heterogeneous base catalysts as hydrotalcite Mg-Al and MgO-Al2O3 mixed oxides in aldol condensation reaction of vanillin. The highest conversion of vanillin was 95.5% when the reaction was carried out at 120oC in 5 hours, using sulfated Y zeolite.

Selective Vanillin Hydrodeoxygenation on Synthetic Takovite Derived NiAlOx Mixed Oxide

A mixed metal-oxide (NiAlOx) obtained from the annealing of a synthetic takovite clay, [(Ni6Al2(OH)16]CO3·4H2O, was used as a catalyst in the hydrodeoxygenation reaction of vanillin, as a model molecule, to simulate deoxygenation of lignin's moieties. The catalysts were characterized by XRD, TPR, XPS and textural analyses and were tested at between 413 and 573 K and 1.2 MPa H2, using a 300 ml batch reactor. The reaction products were analyzed using a gas-chromatograph coupled to a mass detector (GC–MS). The active site is visualized as a Niδ+–O–Al3+ moieties able to dissociate molecular H2 into highly reactive species (H− and H+) for hydrogenation reactions. Depending on the reaction temperature, decarbonylation, hydrogenation, demethoxylation and dehydroxylation reactions occurred in three stages as clearly indicated by Van-Krevelen O/C* vs. H/C* plots. Our study points out that total deoxygenation can be attained at 553 K with a 100% selectivity to products like methyl-cyclohexane and cyclohexane.

Unprecedented Formation of 2,5‐Diaminoquinones from the Reaction of Vanillin with Secondary Amines in Aerobic Conditions

Vanillin is widely used as a flavoring agent in foods, perfumes and in several other applications. Even if huge amounts of vanillin are annually employed in these manufacturing processes, its reactivity is underexplored, especially for the formation of potentially toxic substances. In this context, we observed the formation of orange to red crystalline compounds in the reaction of vanillin with secondary amines in aerobic conditions. NMR and HRMS allowed identifying the products as 2,5‐diamino‐1,4‐benzoquinones. Preliminary investigations of this reaction led to a proposed mechanism involving an oxidative fragmentation of vanillin as the key step. MTT tests did not show any toxic effect up to 0.1 mm.

Comparative Study on the Reaction of Organophosphorus Reagents with Vanillin from Moringa Oleifera Plant. Synthesis of Phosphoranylidenepyranone, Dioxaphospholane and Butenethione Derivatives of Anticipated Antitumor Agents

Vanillin which can be isolated from Moringa oleifera plant was allowed to react with different nucleophilic organophosphorus reagents. Treatment of 4-hydroxy-3-methoxybenzaldehyde (vanillin) with the active phosphacumulene ylides (N-phenyliminovinylidene)- and (2-oxovinylidene)-triphenylphosphorane afforded the homocyclic phosphoranylidene-cyclobutylidenes. On the other hand, its reaction with the satabilized phosphoniumylide, acetylmethylenetriphenylphosphorane gave the corresponding butenone, which reacted with the active phosphacumulene to give finally the pyran derivative. Next, the phenyliminophenol derivative was obtained from the reaction of vanillin with the iminophosphorane. Moreover, dioxaphospholane oxide was isolated from the reaction of vanillin with hexamethylphosphorus triamide. Finally, the butenethione was generated from the reaction of Japanese reagent with vanillin.

Synthesis, Characterization and the Corrosion Inhibition Study of Two Schiff Base Ligands Derived From Urea and Thiourea and Their Complexes with Cu(II) and Hg(II) Ions

The research includes synthesis of [L1] and [L2] Schiff base ligands by the reaction of vanillin with urea and thiourea respectively in 2:1 mol ratio. The two ligands were reacted with CuII ion in 1:2 mol ratio and HgII ion in 1:1 mol ratio. The prepared compounds have been identified by FTIR, U.V-Vis, 1H-NMR (L1, L2 and HgII complex) spectroscopies, microelemental analysis (C.H.N.S), magnetic susceptibility measurements, atomic absorption, chloride content along with conductivity and melting point measurements. According to applied characterization methods, the proposed general formulas of CuII and HgII complexes were [Cu2LnCl4] and [HgLnCl]Cl, respectively, (where n = 1, 2). The ability of corrosion inhibition with two ligands and their cupper complexes has been studied in diluted hydrochloric acid media.