Double Hydrolysis Research Articles

Mechanisms of Polyethylene Terephthalate Pellet Fragmentation into Nanoplastics and Assimilable Carbons by Wastewater Comamonas.

Comamonadaceae bacteria are enriched on poly(ethylene terephthalate) (PET) microplastics in wastewaters and urban rivers, but the PET-degrading mechanisms remain unclear. Here, we investigated these mechanisms with Comamonas testosteroniKF-1, a wastewater isolate, by combining microscopy, spectroscopy, proteomics, protein modeling, and genetic engineering. Compared to minor dents on PET films, scanning electron microscopy revealed significant fragmentation of PET pellets, resulting in a 3.5-fold increase in the abundance of small nanoparticles (<100 nm) during 30-day cultivation. Infrared spectroscopy captured primarily hydrolytic cleavage in the fragmented pellet particles. Solution analysis further demonstrated double hydrolysis of a PET oligomer, bis(2-hydroxyethyl) terephthalate, to the bioavailable monomer terephthalate. Supplementation with acetate, a common wastewater co-substrate, promoted cell growth and PET fragmentation. Of the multiple hydrolases encoded in the genome, intracellular proteomics detected only one, which was found in both acetate-only and PET-only conditions. Homology modeling of this hydrolase structure illustrated substrate binding analogous to reported PET hydrolases, despite dissimilar sequences. Mutants lacking this hydrolase gene were incapable of PET oligomer hydrolysis and had a 21% decrease in PET fragmentation; re-insertion of the gene restored both functions. Thus, we have identified constitutive production of a key PET-degrading hydrolase in wastewater Comamonas, which could be exploited for plastic bioconversion.

Comprehensive Mechanistic View of the Hydrolysis of Oxadiazole-Based Inhibitors by Histone Deacetylase 6 (HDAC6).

Histone deacetylase (HDAC) inhibitors used in the clinic typically contain a hydroxamate zinc-binding group (ZBG). However, more recent work has shown that the use of alternative ZBGs, and, in particular, the heterocyclic oxadiazoles, can confer higher isoenzyme selectivity and more favorable ADMET profiles. Herein, we report on the synthesis and biochemical, crystallographic, and computational characterization of a series of oxadiazole-based inhibitors selectively targeting the HDAC6 isoform. Surprisingly, but in line with a very recent finding reported in the literature, a crystal structure of the HDAC6/inhibitor complex revealed that hydrolysis of the oxadiazole ring transforms the parent oxadiazole into an acylhydrazide through a sequence of two hydrolytic steps. An identical cleavage pattern was also observed both in vitro using the purified HDAC6 enzyme as well as in cellular systems. By employing advanced quantum and molecular mechanics (QM/MM) and QM calculations, we elucidated the mechanistic details of the two hydrolytic steps to obtain a comprehensive mechanistic view of the double hydrolysis of the oxadiazole ring. This was achieved by fully characterizing the reaction coordinate, including identification of the structures of all intermediates and transition states, together with calculations of their respective activation (free) energies. In addition, we ruled out several (intuitively) competing pathways. The computed data (ΔG‡ ≈ 21 kcal·mol-1 for the rate-determining step of the overall dual hydrolysis) are in very good agreement with the experimentally determined rate constants, which a posteriori supports the proposed reaction mechanism. We also clearly (and quantitatively) explain the role of the -CF3 or -CHF2 substituent on the oxadiazole ring, which is a prerequisite for hydrolysis to occur. Overall, our data provide compelling evidence that the oxadiazole warheads can be efficiently transformed within the active sites of target metallohydrolases to afford reaction products possessing distinct selectivity and inhibition profiles.

Acidic sites enhanced ultra-deep desulfurization performance of novel NiZnO-based mixed oxides mesoporous adsorbents

A series of novel mixed metal oxides (MOs), such as ZnO-Al2O3, ZnO-Al2O3-SiO2, and ZnO-SiO2, were prepared through the double hydrolysis technique and applied as supports for Ni/MOs. The desulfurization activities of these Ni/MOs-based sorbents were investigated in a fixed bed reactor by model gasoline. Results reveal that the reactive adsorption desulfurization efficiency of sorbents was reduced in the order: 10%Ni/ZnO-Al2O3 ˃ 10%Ni/ZnO-Al2O3-SiO2 ˃ 10%Ni/ZnO-SiO2. Among them, the 10%NiZnO-Al2O3 adsorbent exhibited superior desulfurization performance. It achieved the highest breakthrough (10 ppm) up to 78 mL of model gasoline fuel flow, corresponding to 154 mg S/g accumulated sulfur capacity at a breakthrough point, which is four folds higher than the previously reported studies on NiZnO-based materials. The characterizations indicated that the 10%NiZnO-Al2O3 based mixed oxide adsorbent prepared using the double hydrolysis procedure comprises higher Lewis and Lewis/Brønsted ratio acid sites, higher surface area, greater pore size distribution, and a lesser amount of inactive ZnAl2O4 spinel, resulting in a better ZnO dispersion. Moreover, the well-developed pore volume reduced the diffusion resistance of reactant molecules to highly concentrated acid sites, thus leading to higher thiophene conversion and accumulated sulfur adsorption capacity. Based on our results, a mechanism is planned for the reactive adsorption desulfurization activity.

Design of CDs/SiO2 Composite Phosphors via a Double Hydrolysis Reaction and their Expectable Luminescence Performance

Carbon dots (CDs), as an emerging carbon material, have attracted considerable interest for their promising luminescent properties. However, the inevitable aggregation of CDs in solid-state results in some bottleneck problems such as aggregation-induced quenching and foster resonance energy transfer. Therefore, developing solid-sate CDs with good luminescent performance is still a challenge. Herein, a simple and low-cost approach is presented to prepare the solid-state CDs/SiO2 composite in which the CDs were well dispersed and embedded in inorganic silica gel, hence restraining the natural issues of the solid-state CDs. As expected, the CDs/SiO2 composite phosphors showed higher fluorescence intensity about twice than the CDs aqueous solution, and a high photoluminescence quantum yield of 21%. This work would be of significance for the preparation of CDs and even their practical applications.

Interactions of Ni/ZnO with alumina support and their influence on deep reactive adsorption desulfurization

Double hydrolysis mesoporous alumina (DHA) synthesized via hydrothermal technique and used as support for the loading of ZnO and Ni. The desulfurization activities and their interactions of Ni/ZnO/DHA adsorbents were compared with Ni/ZnO supported on commercially prepared alumina (Com). The higher breakthrough desulfurization activity and sulfur adsorption capability of these catalysts are influenced by the binding extant of Zn/Ni atoms with Al2O3 support, more free ZnO/Ni species and the formation of inactive ZnAl2O4 phases. The catalysts were characterized using nuclear magnetic resonance (NMR) spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, H2-temperature programmed reduction (H2-TPR) and N2 adsorption-desorption. Desulfurization activity shows that Ni/ZnO/DHA-80 °C catalyst achieved an excellent breakthrough sulfur removal (10 mg/L) up to 30.26 mL responsible for 110.4 mg S/g sulphur adsorption capability. This desulfurization performance is one fourth fold higher as compared to commercial Ni/ZnO/Com catalyst, achieving a compromised desulfurization activity of 1300 mg/L at set 30.26 mL model fuel flow with 38 mg S/g accumulative sulfur capacity. Detailed characterization results show that, the superior desulfurization activity shown by Ni/ZnO/DHA catalyst is due to the presence of meagre amount of unsaturated pentacoordinate Al3+ centers on Ni/ZnO/DHA surface which are responsible for lesser interaction of Ni/ZnO with Al2O4 and reduce the formation of inactive spinal ZnAl2O4 and NiAl2O4 phase even after many regeneration cycles which increases the active ZnO molar concentration as compared to Ni/ZnO/Com catalyst.

Synthesis of Micron-Sized NiAl/NiCoAl-Layered Double Hydroxides via a Facile Double Hydrolysis Dropping Method for Supercapacitor Applications

The transition metal-based layered double hydroxides (LDHs) for high-performance supercapacitor applications were synthesized by the double hydrolysis dropping method. We found that the dropping sequence of the cation and anion solutions has a strong influence on the microstructural and electrochemical properties of LDHs. The NiAl LDHs obtained by dropping the Ni2+ solution into the AlO2- solution have obvious layered structures with a particle size of the order of micrometers. They are different from those LDHs prepared by the conventional double hydrolysis method and hydrothermal method. The specific capacity of the NiAl LDHs is about 615 C g−1 at 0.5 A g−1, which is almost twice that of the sample synthesized by the traditional double hydrolysis method (339 C g−1). It is indicated that the performance of the NiAl LDHs is improved by the dropping method. Moreover, an excellent cyclic stability of 83.3% capacitance retention after 1000 cycles at 3 A g−1 was achieved. In addition, the trimetallic NiCoAl LDHs have been synthesized successfully by the dropping method. The results showed that the addition of Co effectively enhanced the electrochemical properties of LDHs. The optimal NiCoAl LDHs display an excellent specific capacity of 990 C g−1 at 0.5 A g−1. This work offers an efficient and facile route, without hydrothermal treatment or adscititious alkali sources, to fabricating LDHs for boosting energy storage capabilities.

Facile one-pot synthesis of Ni-based catalysts by cation-anion double hydrolysis method as highly active Ru-free catalysts for green H2 production via NH3 decomposition

A series of Ni/Al1CeaOx composites prepared by various synthetic methods, including one-pot anion-cation double hydrolysis (CADH), co-precipitation (CP), CADH followed by wet impregnation (CADH-WI), and CP followed by wet impregnation (CP-WI) were employed as catalysts for ammonia (NH3) decomposition to generate hydrogen. The results revealed that the catalyst prepared by the one-pot CADH method exhibited outstanding catalytic performance (complete NH3 decomposition at around 550 °C) mainly because of significant enhancement in Ni dispersion, Ni reducibility, the quantity of surface oxygen vacancy, and NH3 adsorption affinity. The superior catalytic performance of Ce-containing catalysts over Ni/Al2O3 catalyst was ascribed to the synergistic effects of NiO reducibility, surface oxygen vacancies, basicity, and Ni-support interaction. The selected catalysts demonstrated excellent stability during 100 h continuous operation, without any obvious decrease in NH3 conversion. Overall, the proposed one-pot CADH method offers great advantages in preparing highly active and stable Ni-based catalysts for NH3 decomposition.

From coating to doping: Effect of post-annealing temperature on the alumina coating of LiNi0.5Mn1.5O4 cathode material

Spinel LiNi0.5Mn1.5O4 is considered as one of the most promising cathode materials due to high working voltage and high energy density. However, the fast capacity degradation, mainly induced by the instability of electrode/electrolyte interface and bulk structure, heavily prevents its commercial application. To alleviate above two issues, LiNi0.5Mn1.5O4 material was first coated with Al(OH)3 via double hydrolysis reactions between NaAlO2 and AlCl3·6H2O, where the corrosion of LiNi0.5Mn1.5O4 material is avoided by controlling the feeding sequence, and the uniform coating of Al(OH)3 on particle surface is achieved by controlling the feeding rate. The Al(OH)3-coated LiNi0.5Mn1.5O4 material was post-annealed at different temperatures, and the effects of different post-annealing temperatures on the structure, morphology and electrochemical performance of LiNi0.5Mn1.5O4 material were systematically investigated. It is found that the LiNi0.5Mn1.5O4 material after post-annealing treatment at 600 ​°C exhibits the optimal rate and cycling performances, which can be mainly attributed to the synergistic effect of Al2O3 surface coating and doping. The uniform and thin Al2O3 coating layer can avoid the direct contact of electrode with electrolyte, capture corrosive HF and increase oxygen vacancy on particle surface, while Al3+ doping can eliminate LixNi1-xO impurity phase, reduce Mn3+ content, strengthen the spinel structure and make Li+ ions diffusion easier, thus leading to the simultaneous improvement of interfacial and structural stability of LiNi0.5Mn1.5O4 material.

Reaction characteristics and compressive strength of magnesia-phosphate cement at negative temperatures

Magnesia-phosphate cement (MPC) is considered the most promising inorganic cementing material for the rush-repair construction of concrete structures, pavements, and airport runways in negative-temperature environments. To prepare MPC repair materials that are suitable for negative temperatures, we studied and quantitatively analyzed the influences of dead-burned magnesia/phosphate (M/P), borax/dead-burned magnesia (B/M), and water/MPC (W/C) ratios on the reaction rate, early strength, and long-term strength of MPC prepared and cured at negative temperatures. The ice point of the mixed water decreased to −10 °C because of the double hydrolysis role of monoammonium phosphate and borax; therefore, MPC could set and harden at temperatures higher than −10 °C, and its 2 h compressive strength was > 15 MPa. The setting and reaction rate of MPC decreased steeply with decreasing temperature, and the 2 h compressive strength was as low as 3.0 MPa at − 20 ± 2 °C. The early strength of MPC enhanced on increasing the magnesium ion concentration in the MPC slurry, and the 2 h compressive strength of MPC at − 10 ± 2 °C increased by approximately 50% when the M/P ratio increased from 3 to 5. The early strength of MPC at negative temperatures was more sensitive to changes in the B/M and W/C ratios than at room temperature (20 ± 2 °C). When the temperature of the frozen MPC specimens that were maintained at − 10 ± 2 °C and − 20 ± 2 °C was increased to room temperature, the long-term strength of the MPC increased to approximately 80.9% and 67.6%, respectively, than that of the MPC maintained at room temperature, owing to the secondary reaction in the MPC.

In-situ synthesis of amorphous FeO(OH) coated ultrafine SnO2 on the surface of CNT as anode for lithium ion batteries

Robust SnO2-based anode materials for lithium ion batteries (LIBs) are currently suffering from extremely large volume changes which may lead to quick capacity decay in the cycling process. Recent researches indicate that amorphous materials can improve the cycling performances of LIBs, inspiring us to create amorphous coatings as accommodations for the stress caused by volume expansion. Here, a hydrothermal amorphous FeO(OH) coated ultrafine SnO2 nanocrystals on carbon nanotubes (CNTs) anode materials for LIBs are prepared from the precursor of H2SnO3@Fe(OH)3 fabricated by a double hydrolysis reaction. Due to the disorder of the atomic arrangement of amorphous state, the FeO(OH) coatings have excellent elasticity, which can buffer the volume expansion of SnO2 nanoparticles as well as themselves. Moreover, the amorphous coatings together with CNTs conductive networks can also suppress the agglomeration of SnO2 nanoparticles during the cycling process. The flexible amorphous coatings, well dispersed and ultrafine active particles, as well as highly conductive networks in the constructed architecture endows this novel anode materials a good long-cycle stability and rate performance, so that a high specific capacity of 400 mA h g−1 can be retained at 2 C (1.44 A g−1) after 500 cycles.

The influence mechanism of HCO3− on fluoride removal by different types of aluminum salts

In order to study the influence mechanism of HCO3− on the fluoride removal by AlCl3 and Al13, the residual fluoride concentration, residual aluminum concentration and pH value in coagulation effluent were measured at different HCO3− concentrations. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was used to analyze the aluminum species in the supernatant after coagulation, and the flocs collected were analyzed by nuclear magnetic resonance (NMR) and X-ray photoelectron spectra (XPS). The results show that AlCl3 is used as a coagulant, when the concentration of HCO3− increases from 100 mg/L to 300 mg/L, Al3+ and HCO3− are double hydrolyzed to form Al(OH)3 alum flower after adding AlCl3, and the removal rate of fluoride rapidly increases from 9.55 % to 78.0 %. When the concentration of HCO3− increases from 300 mg/L to 1000 mg/L, the precipitation of Al(OH)3 will gradually dissolve to form Al(OH)4− and the removal rate of fluoride drops from 78.0 % to 56.2 %. When Al13 is used as a coagulant, with the increase of HCO3− from 100 mg/L to 1000 mg/L, its double hydrolysis with Al-F complexes is enhanced, resulting in the formed Al6F2, Al7F2 and Al9F3 gradually dissociate, and the removal rate of fluorine decreases from 78.8 % to 59.4 %.

Carbon Nanotube Reinforced Natural Fibers for Biodegradable Nanocomposites

Natural fiber-reinforced nanocomposites (NFRCs) are proved as the best alternative for synthetic composites in view of cost and environmental effects. NFRCs have been produced from agro-waste such as banana tree fiber (BFs), because of BF are strong, light-weight, have smaller elongation. To improve the quality of BF, multiwall carbon nanotubes (MWCNTs) are used as reinforcing filler, which are functionalized by an ecofriendly radio frequency oxygen plasma processing method. cellulose nano-crystals (CNC) is extracted from BFs by double hydrolysis process and a simple dip-drying technique has been used to produce NFRCs. Field emission scanning electron micrographs and transmission electron microscopy conform the well dispersion of MWCNTs in the BF matrix. Thermal stability and mechanical strength of the NFRCs are improved owing to the incorporation of MWCNTs. Functional groups in the BFs, CNC and NFRCs are investigated by Fourier transform infrared spectroscopy. The current density of the sample is increased 1000 times and conductivity increases up to 17 Sm−1, which increases with temperature. Therefore, these light-weight biodegradable NFRCs encourage its ability as cost effective industrial conductive composite as usable in electronic devices.

Carbon Nanotube Reinforced Natural Fibers for Biodegradable Nanocomposites

Natural fiber-reinforced nanocomposites (NFRCs) are proved as the best alternative for synthetic composites in view of cost and environmental effects. NFRCs have been produced from agro-waste such as banana tree fiber (BFs), because BF are strong, light-weight, and have smaller elongation. To improve the quality of BF, multiwall carbon nanotubes (MWCNTs) are used as reinforcing filler. MWCNTs are functionalized by an ecofriendly radio frequency oxygen plasma processing method. Cellulose nano-crystals (CNC) are extracted from BFs by double hydrolysis process and a simple dip-drying technique has been used to produce NFRCs. Field emission scanning electron micrographs and transmission electron microscopy conform the well functionalization of MWCNTs and also ensure homogeneous incorporation in the BF matrix. The composites continue thermally stable corresponding to BFs. Mechanical strength of the NFRCs are improved owing to the incorporation of MWCNTs. Functional groups in the BFs, CNC and NFRCs are investigated by Fourier transform infrared spectroscopy. The current density of the sample is increased 1000 times than the raw fibers and conductivity increases up to 17 Sm^-1, which increases with temperature under the applied voltage 100 V and shows the linier characterization. Therefore, these light-weight biodegradable NFRCs encourage its ability as cost effective industrial conductive composite as usable in electronic devices.

CO2 Reforming of Methane over a Highly Dispersed Ni/Mg–Al–O Catalyst Prepared by a Facile and Green Method

A novel Ni/Mg–Al–O catalyst has been successfully synthesized by the cation–anion double hydrolysis (CADH) method for carbon dioxide (CO2) reforming of methane. Compared with the Ni/MgO–Al2O3 catal...

Cu/Al2O3 catalyst prepared by a double hydrolysis method for a green, continuous and controlled N-methylation reaction of nitroarenes with methanol

Cu/Al2O3 catalyst was developed by a double hydrolysis precipitation. Over the Cu/Al2O3 catalyst, a continuous mode of N-methylations of nitroarenes with methanol was successfully achieved under the exogenous base- and H2- free condition. Methylation process of nitroarenes could be controlled just by adjusting reaction conditions, affording the desired N-monomethylanilines or N, N-dimethylanilines, respectively. The characterization displayed that the double hydrolysis precipitation method made active metal Cu surface enrichment and high dispersion, meanwhile endow Cu/Al2O3 with more developed pore system, which were responsible for the higher performance of our catalyst relative to Cu/Al2O3-CP. Compared with the reported batch mode, our procedure possessed the merits of low cost, environment-friendliness, better controllability and wide universality.

Low Li ion diffusion barrier on low-crystalline FeOOH nanosheets and high performance of energy storage

To obtain symmetric supercapacitors (SCs) with high energy density, it is critical to fabricate an electrode with wide potential window and excellent capacitive performance. Herein, by using the strong double hydrolysis reaction between anions and cations, the FeOOH nanosheets on the surface of activated carbon cloth (FeOOH@AC) are prepared through a simple hydrothermal process. The FeOOH@AC electrode exhibits maximum capacitance of 4,090 mF·cm−2 at wider potential window -1–0 V and 3,250 mF·cm−2 at 0–1 V versus SCE in 2 M LiNO3 electrolyte. With two pieces of FeOOH@AC electrodes the obtained symmetric SC can operate at the voltage window of 2 V. This FeOOH symmetric SC shows high energy density of 13.261 mWh·cm−3 at a power density of 14.824 mW·cm−3 and maintains 4.175 mWh·cm−3 at a maximum power density of 118.564 mW·cm−3, as well as excellent charge storage capacity and cyclic stability. Li ion adsorption and diffusion mechanism on the (200) facets of FeOOH are explained by the density functional theory (DFT) calculations. The simple synthesis process and excellent capacitance performance of the FeOOH@AC composite make it a very promising candidate for high performance symmetric SC electrodes.

Rapid preparation of ultra-fine and well-dispersed SnO2 nanoparticles via a double hydrolysis reaction for lithium storage.

An efficient and rapid method is reported for preparing ultra-fine and well-dispersed SnO2 nanoparticles in a large scale. A simple double hydrolysis reaction between SnO32- and Fe3+ ions was masterly used to form a stable colloid system, in which colloidal particles of H2SnO3 with negative charges and Fe(OH)3 with positive charges electrostatically interact with each other and form honeycomb-like "core-shell" units. Through the hydrothermal reaction, the units are easily transformed into SnO2@FeO(OH) structures. Ultra-fine and well-dispersed SnO2 particles with less than 6 nm diameter were finally obtained with a high yield by further etching using hydrochloric acid. When used as anode materials for lithium ion batteries, the ultra-fine SnO2 particles can be easily dispersed into the carbon networks originating from the carbon source of glucose during the hydrothermal reaction. Electrochemical tests confirmed that these ultra-fine SnO2/C materials were endowed with excellent cyclic stability and C-rate performance. Even at a 1.56 A g-1 (2C) high current density, the reversible capacity could be maintained at 710 mA h g-1 after 100 cycles owing to the ultra-fine particle size of SnO2 and the rich carbon networks.

Surfactant-free preparation of mesoporous solid/hollow boehmite and bayerite microspheres via double hydrolysis of NaAlO2 and formamide from room temperature to 180 °C

The transformation from solid boehmite microspheres to hollow bayerite microspheres at room temperature (25 °C) was successfully realized via the double hydrolysis of NaAlO2 and formamide (FA) solution. Effects of reaction time, temperature and FA dos on the transformation process were studied in detail. The results show that hollow boehmite microspheres were obtained via increasing the temperature above 120 °C and the FA dos above 12 mL; amorphous alumina hydrate, solid boehmite and hollow bayerite microspheres were also obtained at 25 °C for 1 h, 2 h and 24 h reactions, respectively; solid bayerite microspheres were obtained by decreasing the FA dos below 4 mL at 25 °C. Because of the slow change of pH from 12.9 to 8.7, simultaneous dissolution and regeneration for different aluminum hydroxide were the key factors for forming hollow boehmite/bayerite microspheres. The Al yield for boehmite microspheres reached 41.4% at 25 °C for a 2 h reaction; when increasing the temperature to 180 °C, the Al yield for hollow boehmite microspheres with higher crystallinity increased to 82.7%. Moreover, the solid/hollow boehmite microspheres with high surface areas showed outstanding adsorption capacities of 751.9 mg/g and 694.4 mg/g, respectively, for Congo red. This significant transformation of structure and morphology provides an effective strategy for preparing mono-phase hydrated alumina with excellent adsorption performance.

Ion exchange for ZnAl‐LDHs using ammonium‐salt method in aqueous medium

The intercalated anion species of layered double hydroxides (LDHs) largely determine their application performance. This work investigated the ion exchange process from CO 3 2- - to NO 3 - -type LDHs in aqueous medium using the ammonium salt method, and found that a complete ion exchange reaction can be performed by heat treatment. The weak acidity of aqueous NH 4 NO 3 solutions can protonate the interlayered CO 3 2- to HCO 3 - and then NO 3 - intercalates for the charge compensation; heating at temperatures above 80° C enables the double hydrolysis of HCO 3 - and NH 4 + to CO 2 and NH 3 gases, which is proposed to be a kinetically indispensable factor to complete the NO 3 - /CO 3 2- ion exchange. The heating treatment could reduce the salt dosage and greatly shorten the reaction time to 1 h. In the ion exchange process, mass losses of ZnAl-LDHs take place due to the dissolution of hydroxide layers, and the dissolution rate of Zn increases with an increase in the heating time, but Al is hardly dissolved. The present work also demonstrated that the proposed method can be appropriate for a complete ion exchange of SO 4 2- or I - for CO 3 2- .

Synthesis of 2-(12-aryldodecanoyl)cyclohexane-1,3-diones

Synthesis was developed of 2-(10-undecenoyl)cyclohexane-1,3-diones containing in the side chain keto and hydroxy groups and a phenyl substituent. The synthesis is underlain by a nitrile oxide approach. The scheme included isoxazole synthesis for the protection of the β,β′-tricarbonyl fragment, building up of a heterocycle by 1,3-dipolar cycloaddition of nitrile oxide in situ to the terminal double bond, cycle opening (of isoxazole and isoxazoline), and alkaline hydrolysis.