Iranian Journal of Catalysis
Volume:5 Issue: 3, Summer 2015

Amidoalkyl-2-naphthols as synthetic intermediates play an important role in medicinal chemistry due to their remarkable biological and many pharmacological properties. Owing to the versatile biological activities, industrial and synthetic applications of these compounds, introduction of an alternative methodology is urgent in synthetic organic chemistry. Low yield and harsh reaction conditions promoted the researchers for the development of novel green catalysts for the synthesis of amidoalkyl-naphthols. Therefore in the present review, we deal with green catalytic synthesis of amidoalkyl-naphthols. The main purpose of this review is to present a survey of the literature on various heterogenous and homogenous catalysts used for the synthesis of amidoalkyl-naphthols alongwith mechanism of reaction since synthesis of such compounds have not been previously reviewed.

The catalytic cracking of a fuel oil over fluid catalytic cracking (FCC) catalyst has been investigated applying different additives. Catalyst mixtures consisting of a equilibrium FCC catalyst (E-Cat) blended with ZSM-5, MCM-41 and Mordenite additives were examined at the additive levels of 25 wt.%. The catalytic performance of the matrix was studied in a fixed bed micro-activity test unit (MAT) at 600 ˚C and catalyst/oil ratio of 3.6. Two types of ZSM-5 with different Si/Al ratios were utilized. Results indicate that the yield of light olefins significantly increased by operating hybrid catalysts in comparison with the base E-Cat. The highest olefin yield of 61.46 wt.% in the gas phase products was achieved over E-Cat/ZSM-5 of low Si/Al ratio. The maximum propylene production was observed over MCM-41, besides applying mordenite as additive showed more propylene to ethylene ratio in products. Butenes were also increased by use of all additives, whereas iso-butene shows the maximum yield over all E-Cat/additives.

A series of transition metal complexes with two thiosemicarbazide Schiff bases, 1-(4-dimethylaminobenzyl- idene)thiosemicarbazide (ABTSC) and 1-(2-pyridincarboxyl-idene) thiosemicarbazide (TCTS) were synthesized with Co(II), Ni(II), Zn(II), Cd(II) and Ag(I) salts (chloride and acetate). These complexes were characterized by different methods including proton nuclear magnetic resonance (1HNMR), Fourier transform infrared (FT-IR), ultra violet visible (UV-Vis), molar conductance (λm), atomic absorption spectroscopy (AAS) and elemental analysis (CHNS). All complexes were applied as a catalyst for oxidation of aromatic alcohols. The effects of reaction time, temperature, catalyst amount, oxidant and solvents were investigated in detail. The oxidation of alcohols occurs effectively and selectively with H2O2 as the oxidant. For instance, 4-Methoxybenzyl alcohol is oxidized to the corresponding aldehyde with 95% conversion and 100 % benzaldehyde selectivity under the optimum conditions.

A mild, efficient and fast method for the oxidation of alcohols and trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using CrO3 in the presence of rice husk ash (RHA) is reported. All reactions were performed at room temperature in high to excellent yields. A new, efficient and green catalyst, heterogeneous reaction conditions, easy work-up of the products and high reaction rates are the main advantages of this method.

A mild and efficient method has been developed for the preparation of substituted coumarins from reaction of various phenols with different β-ketoesters via Pechmann condensation in the presence of Brønsted acidic ionic liquid (N-(4-sulfonic acid) butyl triethylammonium hydrogen sulfate) as an effective catalyst under solvent-free conditions. Different phenols reacted with ethyl acetoacetate to produce the corresponding substituted coumarins in high to excellent yields and short reaction times. Moreover, [TEBSA][HSO4] has been used as an effective green catalyst for the synthesis of coumarin derivatives under solvent-free conditions. Using the relatively non-toxic (halogen-free) and reusable Brønsted acidic ionic liquid, high catalytic efficiency, high yields, short reaction times and straightforward work-up are advantages of this protocol.

A simple, green and efficient method for synthesis of 2,4,5-trisubstituted imidazoles is described via three-component cyclocondensation of benzil or benzoin, aldehyde and ammonium acetate by using the nano SiO2-supported ferric hydrogen sulfate (FHS/SiO2), as a catalyst, under solvent-free conditions. The nano SiO2 support and catalyst were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and IR spectroscopy. In this project, the optimum conditions such as: reaction temperature, reaction time and amount of catalyst were investigated. The major advantages of the present method are high yields, shorter reaction times, easy work-up, purification of products by non-chromatographic method and the reusability of the catalyst.

Facile and versatile procedures have been explored for the synthesis of tetrahydropyridines and 2,3-dihydroquinazolin-4(1H)-ones. These protocols employ the one-pot multi-component condensation of arylaldehydes and aromatic amines with β-keto esters and isatoic anhydride in chloroacetic acid, respectively. The reactions proceeded smoothly to generate the corresponding products in high yield. We have found that the use of chloroacetic acid as catalyst results in a remarkable beneficial effect on the reaction, allowing it to be performed without the need of any co-catalyst, which is the case in other similar reported methodologies. In addition, the preparation of 2,3-dihydro-4(1H)-quinazolinones derivatives from the reaction of arylaldehydes and anthranilamide in the presence of mentioned catalyst is reported.

The utilization of hydroxy sodalite (H-SOD) as catalyst under solvent-free condition is described for the efficient preparation of tetrahydrobenzo[b]pyrans. These compounds are synthesized by three-component reactions of aldehydes, alkylnitriles and dimedone. H-SOD that is the waste-product of zeolite manufacturing process is used as an efficient and a very inexpensive catalyst. Furthermore, it can be reused for several rounds without significant loss of activity. The key features of this reported protocol are neutral conditions, excellent yields, short reaction time, simple work-up and recovery and reusability of catalyst. Small E-factor and large percent of reaction mass efficiency, which are very useful metrics for industry, are advantages of this environmentally benign process.

An organosuperbase (N,N-dimethylbiguanide) immobilized on mesoporous and magnetically separable silica supports, was found for the first time, to act as a highly-stable, scalable and efficient heterogeneous catalyst for the Henry reaction under mild and neutral condition. Several factors such as catalyst amount, solvent and reaction time concerning the reactivity were also discussed. The procedure constitutes the first immobilized biguanide promotion of selective synthesis of β-nitroalcohols without addition of stoichiometric amount of any base and showed a broad substrate scope. The uniqueness of this catalyst lay in its cleanness, cost-effectiveness, ease in removal at the end of reaction, and chemoselective formation of a wide range of β-nitroalcohols. These materials can be easily converted to other useful synthetic intermediates which many of them have been exemplified in synthetic organic chemistry and pharmaceutical industry.

Friedel–Crafts synthesis of triarylmethanes over 3-methyl-1-sulfonicacid imidazolium tetrachloroaluminate under green conditions:In this work, Friedel–Crafts (FC) alkylation of various arenes with aromatic aldehydes catalyzed by 3-methyl-1-sulfonic acid imidazoliumtetrachloroaluminate {[Msim]AlCl4}, as a green catalyst, to prepare triarylmethanes (TAMs) has been carried out. Some aromatic aldehydes were reacted with arenes containing electron-donor substitutions such as anisole, veratrole, phenols, indole and 2-naphtole under solvent-free conditions. The catalyst was recovered and reused successfully for four times. Simple methodology, easy work up, solvent-free condition and excellent yields are some advantages of this work.The promising points for the presented method are high yield, green reaction profile, easier work up and simplicity which make it a useful process for the preparation of various triarylmethanes

Gas diffusion electrode was used for providing better conditions in fuel cell systems for oxygen reduction reaction (ORR). Because the slow kinetics of the oxygen reduction reaction at the proton exchange membrane fuel cell cathode restricts fuel cell efficiency. To this end, researchers have used platinum-coated carbon. In the present study, due to the reduction of carbon corrosion, Zinc oxide nanoparticles have been employed as a support material for platinum. The Pt/ZnO nanoparticles catalyst was made via a combined process of impregnation and seeding method. The microstructure of coating was characterized using scanning electron microscopy (SEM) which indicates that Pt nanoparticles are uniformly dispersed on the surface of ZnO. In order to investigate the chemical composition and crystalline phases of coating, X-ray analysis was carried out. Electrochemical Impedance Spectroscopy (EIS) was carried out for comparing the charge transfer effect during the ORR. The catalytic performance of the electrodes for ORR is evaluated through linear sweep voltammetry measurement. The O2 reduction current for Pt/ZnO alone is expectedly low due to the low electronic conductivity in ZnO. However, adding single-wall carbon nanotube (SWCNT) to the reaction layer improves the electrode performance. The prepared Pt/ZnO/SWCNT 30 wt. % electrode shows high catalytic activity for the ORR, which is probably attributed to conductivity changes caused by the addition of SWCNT. The electrochemical active surface area (ECSA) and durability investigation was studied by cyclic voltammetry in nitrogen saturated 0.5 M H2SO4. The results calculated from ECSA measurements were indicated that the degradation rate of optimized electrode is smaller than Pt/C electrode.

Zinc ferrite (ZnFe2O4) nanoparticles were synthesized via the auto-combustion assisted sol-gel method of Zn2+ and Fe3+ ions (molar ratio 1:2) in ammonia solution. The prepared nanomagnetic catalyst was characterized by IR, XRD, SEM and ICP. The diameter of the ZnFe2O4 MNPs (63.7 nm) was determined by Debye-Scherre equation via their XRD pattern. Nanomagnetic ZnFe2O4 efficiently catalyzes oxidation of alcohols and gave the corresponding carbonyl-containing products in good yields. The reactions were carried out in an aqueous medium at r.t in the presence of oxone (potassium hydrogen monopersulfate) as an oxidant. In addition, the catalysts could be reused up to 5 runs without significant loss of activities.

Mahmoud Zarei was born in Hamedan, Iran in1986. He received his B.Sc. in Pure Chemistry (2010) from Islamic Azad University Arak and M.Sc. in Organic Chemistry (2013) at Bu-Ali Sina University, Iran. He is currently working towards his Ph.D. under the supervision of Professor Mohammad Ali Zolfigol. His research interest is catalysis, including the application of homogeneous and heterogeneous catalysis in organic synthesis.