Novel Xanthate Complexes for the Size Controlled Synthesis of Copper Sulfide Nanorods

We present a simple, easily scalable route to monodisperse copper sulfide nanocrystals by the hot injection of a series of novel copper­(I) xanthate single-source precursors [(PPh₃)₂Cu­(S₂COR)] (R = isobutyl, 2-methoxyethyl, 2-ethoxyethyl, 1-methoxy-2-propyl, 3-methoxy-1-butyl, and 3-methoxy-3-methyl-1-butyl), whose crystal structures are also reported. We show that the width of the obtained rods is dependent on the length of the xanthate chain, which we rationalize through a computational study, where we show that there is a relationship between the ground-state energy of the precursor and the copper sulfide rod width

Synthesis of amine functionalized mesoporous silicas templated by castor oil for transesterification

Mesoporous silicas were synthesized via a surfactant-templated sol-gel route using castor oil as the templating agent under acidic medium. The resulting silicas were subsequently amine functionalized with 3-aminopropyltriethoxysilane (NH2-MTS), [3-(2-aminoethylamino)-propyl]trimethoxysilane (NN-MTS), and [3-(diethylamino)propyl]trimethoxysilane(DN-MTS) to introduce surface basicity. Surface physicochemical properties were characterized by field emission gun scanning electron microscopy (FEGSEM), nitrogen porosimetry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). As-synthesised materials exhibit type IV adsorption-desorption isotherms characteristic of mesoporous structures. Clusters of spherical shaped materials were observed by FEGSEM, suggesting growth of silica occurs within colloidal dispersions. High-resolution N 1s XP spectra and DRIFT spectra confirmed the presence of amine groups in the organo-amine functionalised mesoporous silicas. The amine functionalised mesoporous silicas were active for the transesterification of tributyrin with methanol, with conversion found to increase from NH2-MTS< NN-MTS< DN-MTS

Synthesis of bifunctional monomers by the palladium-catalyzed carbonylation of cardanol and its derivatives

The authors thank the Royal Society Leverhulme Africa Program for funding this project.A 1,2-bis(di-tert-butylphosphinomethyl)benzene-modified palladium catalyst has been used to synthesize bifunctional monomers of different chain lengths from cardanol. Short-chain derivatives of cardanol, such as (E)-3-(dodec-8-enyl)phenol; HOPhC12-ene, (E)-3-(undec-8-enyl)phenol; HOPhC11-ene, (E)-3-(dec-8-enyl)phenol; HOPhC10-ene, and 3-(non-8-enyl)phenol; HOPhC9-ene, were synthesized by the metathesis of cardanol with symmetrical internal alkenes. These derivatives were methoxycarbonylated to produce monomers with different chain lengths such as methyl-16-(3-hydroxyphenyl)hexadecanoate; HOPhC15COOMe, methyl-13-(3-hydroxyphenyl)tridecanoate; HOPhC12COOMe, methyl-12-(3-hydroxyphenyl)dodecanoate; HOPhC11COOMe, methyl-11-(3-hydroxyphenyl)undecanoate; HOPhC10COOMe, and methyl-10-(3-hydroxyphenyl)decanoate; HOPhC9COOMe, respectively. Polymerization of the synthesized monomers produced oligomers that consist of up to seven monomer units as confirmed by MALDI-TOF-MS. Lactone formation was also observed in some cases under polymerization conditions.PostprintPostprintPeer reviewe

Valorization of rice husk silica waste:Organo-amine functionalized castor oil templated mesoporous silicas for biofuels synthesis

Rice husk is a rich source of waste silica which has potential for application in the preparation of porous materials for use as catalyst supports or sorbents. Here we report on the synthesis of rice husk silica (RHS) and mesoporous templated rice husk silica (MT-RHS) using sodium silicate, obtained from rice husk ash, and castor oil as a pore directing agent. The resulting silicas were functionalized with 3-aminopropyltriethoxysilane (APTS) or 3-diethylaminopropyltrimethoxysilane (DEPA), and their catalytic activity evaluated in the transesterification of model C4–C12 triglycerides (TAG) to their corresponding fatty acid methyl esters, of relevance to biodiesel synthesis. Castor oil templating enhances the surface area of rice husk silica, and introduces uniform 4 nm mesopores, albeit as a disordered pore network. Post-synthetic grafting of silica by APTS or DEPA resulted in base site loadings of 0.5 and 0.8 mmolg−1 respectively on RHS and MT-RHS. Turnover frequencies of amine-functionalized MT-RHS were 45–65% greater than those of their amine-functionalized RHS counterparts for tributyrin transesterification. Switching from a primary (APTS) to tertiary (DEPA) amine increased activity three-fold, delivering 80% tributyrin conversion to methyl butyrate in 6 h. DEPA-MT-RHS was effective for the transesterification of C8 and C12 triglycerides, with methyl caproate and methyl laurate selectivities of 93% and 71% respectively in 24 h

Potential Biological Applications of Bio-Based Anacardic Acids and Their Derivatives

Cashew nut shells (CNS), which are agro wastes from cashew nut processing factories, have proven to be among the most versatile bio-based renewable materials in the search for functional materials and chemicals from renewable resources. CNS are produced in the cashew nut processing process as waste, but they contain cashew nut shell liquid (CNSL) up to about 30–35 wt. % of the nut shell weight depending on the method of extraction. CNSL is a mixture of anacardic acid, cardanol, cardol, and methyl cardol, and the structures of these phenols offer opportunities for the development of diverse products. For anacardic acid, the combination of phenolic, carboxylic, and a 15-carbon alkyl side chain functional group makes it attractive in biological applications or as a synthon for the synthesis of a multitude of bioactive compounds. Anacardic acid, which is about 65% of a CNSL mixture, can be extracted from the agro waste. This shows that CNS waste can be used to extract useful chemicals and thus provide alternative green sources of chemicals, apart from relying only on the otherwise declining petroleum based sources. This paper reviews the potential of anacardic acids and their semi-synthetic derivatives for antibacterial, antitumor, and antioxidant activities. The review focuses on natural anacardic acids from CNS and other plants and their semi-synthetic derivatives as possible lead compounds in medicine. In addition, the use of anacardic acid as a starting material for the synthesis of various biologically active compounds and complexes is reported

Specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions in aqueous media

A comparative study of specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas hydrochloric acid was employed for specific acid catalysis. At equimolar amounts of copper(II) nitrate and hydrochloric acid (0.01 M, for example) and under the same reaction conditions, the reaction rate for 1a with 2 is about 40 times faster with copper catalysis than with specific acid catalysis. Moreover, at 32 °Cand 0.01 M HCl, the reaction of 1b with 2 is about 21 times faster than the same uncatalyzed reaction in pure water under the same reaction conditions. The inverse solvent kinetic isotope effect shows that these Diels–Alder reactions undergo specific acid catalysis.

Surfactant-assisted specific-acid catalysis of Diels–Alder reactions in aqueous media

Surfactant-assisted specific-acid catalysis (SASAC) for Diels–Alder reactions of two dienophiles with a cyclopentadiene in aqueous media at 32 °C was studied. This study showed that acidified anionic surfactants (pH 2) such as sodium dodecyl sulfate (SDS) and linear alkylbenzene sulfonic acid (LAS) accelerate Diels–Alder reactions. Conversely, under similar reaction conditions (pH 2) these reactions are inhibited by (acidified) cationic surfactants such as dodecyltrimethylammonium bromide (DTAB), dodecyldimethylammonium bromide (DDAB), and dodecylmethylammonium bromide (DMAB). A modest rate acceleration resulting from the surfactant hydrogen-bonding capacity is also recorded for the Diels–Alder reaction of naphthoquinones with the cyclopentadiene in aqueous media at 32 °C.

Isomerization of anacardic acid:a possible route to the synthesis of an unsaturated benzolactone and a kairomone

Crystalline unsaturated lactone, 8-hydroxy-3-tridecyl-1H-isochromen-1-one (6) has been synthesized by isomerization of anacardic acid having heterogeneous alkyl side chains (a mixture of mono-, di-, and tri-unsaturated anacardic acid) (1). Hydrogenation of 8-hydroxy-3-tridecyl-1H-isochromen-1-one produced a saturated lactone, 8-hydroxy-3-tridecyl-3,4-dihydroisochromen-1-one (7). Isomerization of monoene anacardic acid resulted in a crystalline isoanacardic acid, (E)-2-hydroxy-6-(pentadec-1-enyl)benzoic acid (8) as a major product. This was then metathesized with 2-butene to give 3-prop-1-enylphenol (10). Both isomerization reactions used a 1,2-bis(ditertiarybutylphosphinomethyl)benzene modified palladium catalyst. The two products, 8-hydroxy-3-tridecyl-1H-isochromen-1-one and (E)-2-hydroxy-6-(pentadec-1-enyl)benzoic acid have been crystallographically characterized. Practical applications: Unsaturated lactones are structural elements often found in natural products, which have medicinal value. Benzolactones derived from anacardic acid reported in this work have some structural similarity with lactones such as massoia lactone having medicinal value. Therefore with this idea in mind, the unsaturated benzolactones reported in this work will be tested for their anti pathogenic activity. 3-Propylphenol is used in combination with racemic 1-octen-3-ol and p-cresol to prepare a kairomone for tsetse fly traps. Results from this work describe the suitability of anacardic acid for synthesizing 3-propylphenol. The fact that 3-propylphenol can be synthesized from anacardic acid, a component of cashew nut shell liquid is of particular interest since most of the areas affected with tsetse flies are suitable for growing cashew plants. This means the raw materials (CNSL) for synthesis of 3-propylphenol will be obtained from within the same region where the kairomone is to be applied, although we appreciate that specialized facilities would be required for the types of transformation described.</p