Separation and Purification of Acetophenones from Cynanchum bengei Decne Root Bark by Combination of Silica Gel and High-speed Counter-current Chromatography

[Objectives] To develop a method for separation and purification of acetophenones from Cynanchum bengei Decne root bark by combination of silica gel and high-speed counter-current chromatography( HSCCC). [Methods]The crude extract of Cynanchum bengei Decne root bark was separated by silica gel column chromatography,and parts A and B containing acetophenones were obtained. Then,parts A and B were separated by HSCCC with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water( 4∶ 6∶ 4. 5∶ 5. 5 and4∶ 6 ∶ 3 ∶ 7, V/V), respectively. [Results] From 260 mg of part A, four compounds with p-dihydroxybenzene 3. 9 mg(Ⅰ),4-hydroxyacetophenone 17. 1 mg( Ⅱ),2,5-di-hydroxyacetophenone 13. 3 mg(Ⅲ) and 2,4-dihydroxyaceto-phenone 21. 0 mg(Ⅳ) were obtained. And from 300 mg of part B,136 mg of Radix Cynanchi Bungei benzophenone(Ⅴ) was obtained. The purity of compounds determined by HPLC was 97. 0%,96. 6%,99. 2%,99. 7%,99. 5%,respectively. [Conclusions] The established method is simple and efficient. It can be used for separation of acetophenones from Cynanchum bengei Decne root bark and has better practical value,which could provide a reference basis for development and utilization of Cynanchum bengei Decne root bark.

STUDIES ON THE DEMETHYLATION-ALKYLATION REACTION OF ACETOPHENONES VIA 2-(1,3-DITHIAN-2-YLIDENE)-1-ARYLETHENONES

2-(1,3-dithian-2-ylidene)-1-arylethenones 3 Via chemoselective 1,2-addition with methyl,ethyl, phenyl,allyl,and benzyl Grignard reagents afforded the corresponding alcohols(4).Catalyzing by silica gel,the alcohols 4 were converted to the aryl.ketones(5).The entire process represent a demethylation— alkylation reaction of acetophenones.The mechanism of reaction are proposed and the structure requirement for the conversion of the alcohols(4)was discussed.

A Rapid and Efficient Synthesis of 2,4,6-Triarylpyridines under Microwave Irradiation

An rapid and efficient synthesis of 2, 4, 6-triarylpyridines is reported using substituted benzaldehydes, substituted acetophenones and ammonia as starting materials under microwave irradiation in the presence of PEG-400.

New Convenient Synthesis of 8-C-Methylated Homoisoflavones and Analysis of Their Structure by NMR and Tandem Mass Spectrometry

Homoisoflavonoids are in the subclass of the larger family of flavonoids having one more alkyl carbon than flavonoids. Among them, 8-C-Methylated homoisoflavones have not been extensively studied for synthesis and biological evaluation. Author’s current objective is to synthesize 8-C-Methylated homoisoflavones by the reaction of 3-C-methylated dihydrochalcones with N,N’-dimethyl (chloromethylene) ammonium chloride generated in situ from DMF and PCl5 for one carbon extension at about room temperature. The 3-C-methylated dihydrochalcones were synthesized by the reduction of 3-C-methylated chalcones, which were prepared from 3-C-methylated acetophenones and aromatic aldehydes in the presence of base. All the synthesized novel homoisoflavones’s structures were characterized by NMR and Tandem Mass Spectrometry.

Production of Chiral Aromatic Alcohol by Asymmetric Reduction with Vegetable Catalyst

Chiral aromatic alcohols are the key chiral building block for many important enantiopure pharmaceu-ticals. In this work,we studied asymmetric reduction of prochiral aromatic ketone to produce the corresponding chiral alcohol using vegetables as the biocatalyst. Acetophenone was chosen as the model substrate. The results in-dicate that acetophenone can be reduced to the corresponding chiral alcohols with high enantioselectivity by the chosen vegetables,i.e. apple(Malus pumila),carrot(Daucus carota),cucumber(Cucumis sativus),onion(Allium cepa),potato(Soanum tuberosum),radish(Raphanus sativus),and sweet potato(Ipomoea batatas) . In the reaction,R-1-phenylethanol is produced with apple,sweet potato and potato as the catalyst,while S-1-phenylethanol is the product with the other vegetables as the catalyst. In term of the enantioselectivity and reaction yield,carrot(D. ca-rota) is the best catalyst for this reaction. Furthermore,the reaction characteristics were studied in detail using car-rot(D. carota) as the biocatalyst. The effects of various factors on the reaction were investigated and the optimal reaction conditions were determined. Under the optimal reaction conditions(reaction time 50 h,substrate concen-tration 20 mmol·L-1,reaction temperature 35 °C and pH 7),95% of e.e.(to S-1-phenylethanol) and 85% chemical yield can be obtained. This work extends the biocatalyst for the asymmetric reduction reaction of prochiral aromatic ketones,and provides a novel potential route to produce enantiopure aromatic alcohols.

Asymmetric Bioreduction of 3,5-Bis（trifluoromethyl） Acetophenone to Its Corresponding Alcohol by Candida troplcalis

(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed in high enantiomeric excess (e.e.) through asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Candida tropicalis 104 cells. The influence of some key reaction parameters such as substrate concentration, co-substrate and its concentration, biomass and reaction time was examined, respectively. The results showed that these factors obviously influence the yield, but the optical purity of the prepared product remains intact. The opti-mum conditions for the preparation of (S)-3,5-bistrifluoromethylphenyl ethanol were found to be as follows: sub-strate concentration 50 mmol?L?1; 50 g·L-1 of maltose as co-substrate; wet cell concentration 300 g·L-1; reaction for 30 h. Under above optimal conditions, the maximum yield for (S)-3,5-bistrifluoromethylphenyl ethanol reached 70.3% with 100% of product e.e.

Efficient oxidation of ethylbenzene catalyzed by cobalt zeolitic imidazolate framework ZIF-67 and NHPI

Efficient catalytic oxidation of ethylbenzene to acetophenone was realized using the catalytic system of cobalt zeolitic imidazolate framework ZIF-67/N-hydroxyphthalimide （NHPI） under mild conditions. 95.2% conversion of ethylbenzene with 90.3% selectivity to acetophenone could be obtained at 373 K under 0.3 MPa 02 for 9 h. The results show that there exists synergetic effect between ZIF-67 and NHPI. 1-Phenylethyl hydroperoxide （PEHP） was generated via a radical process involving the hydrogen abstraction from ethylbenzene by phthalimide N-oxyl, and subsequently effectively decomposed to acetophenone by ZIF-67.

Enantioselective hydrogenation of acetophenone by(1S,2S)-DPEN-Ru(Ⅱ)Cl_2(PPh_3)_2 encapsulated in Al-MCM-41

A chiral ruthenium complex[（1S,2S）-DPEN]-RuCl_2（PPh_3）_2（DPEN = 1,2-diphenylethylenediamine,PPh_3 = triphenylphosphine） was encapsulated in the channel of Al-MCM-41 by electrostatic adsorption and 1,1-dichlorosilacyclobutane modification.The prepared heterogeneous catalyst showed the same catalytic activity and enantioselectivity as the corresponding homogeneous catalyst in the asymmetric hydrogenation of acetophenone,and could be reused at least seven times without significant loss of catalytic activity and enantioselectivity.

Hartree-Fock and Density Functional Theory Studies on the Molecular Recognition of the Cyclodextrin

This study involves initial Hartree-Fock and Density Functional theory calculations onthe molecular recognition of the cyclodextrins. The α-cyclodextrin-acetophenone complexationsystem was investigated with PM3, HF/3-21G* and B3LYP/3-21G* methods. The results indicatedthat the inclusion orientation in which the acetyl group of the acetophenone points towards thesecondary hydroxyls of the a-cyclodextrin was preferable in energy. The steric effect wassupposed as the physical reason of such a behavior Hence, the simple rule the anti-parallelarrangement of the dipoles of the host and guest molecules in the cyclodextrin complexqtion is notgenerally applicable.

Enantioselective reduction of acetophenone analogues using carrot and celeriac enzymes system

The enantioselective reduction of acetophenone analogues catalyzed by carrot and celeriac was performed in moderate conversions and excellent enantiomeric excesses.The steric factors and electronic effects of the substituents at the aromatic ring were found to significantly affect the efficiency of the enantioselective reduction of acetophenone analogues,while they had a little effect on the enantioselectivity of acetophenone analogues reduction.It was also found that the conversions of acetophenone analogu...

Efficient C_(2)-Symmetric Chiral Schiff Bases for Lanthanide-catalyzed Asymmetric Hydrogenation of Acetophenone

An array of C2-symmetric chiral Schiff bases of substituted salicylaldehyde （1R, 2R）-1, 2-cyclohexanediamine and （R）-（＋）-2, 2＇-diamino-1, 1＇-binaphthalene, incorporated with lanthanide complexes, have been applied as catalysts for asymmetric hydrogenation of acetophenone for the first time. Highly enantioselective product with 90% enantiomeric excess （e.e.） was obtained when the catalyst, hybridized by the bulky electron-donating 3, 5-di-tert-butyl substituted Schiff base （2） and SmCl3.4THF, was employed.

Seed-mediated synthesis of dendritic platinum nanostructures with high catalytic activity for aqueous-phase hydrogenation of acetophenone

This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum （Pt） nanoparticles （NPs） at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent. It is found that the dendritic Pt NPs （10-150 nm） are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3-5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including： （i） acetophenone conversion rate of 〉 90%, with smaller dendritic Pt NPs （10-46 nm） offering a higher conversion efficiency; （ii） high chemoselectivity toward carbonyl group （90.6%-91.5%）, e.g., the selectivity to l-phenylethanol is -90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 rain, under mild reaction conditions （20 ℃, 1.5 bar H2 pressure, and 1.5 tool% catalyst）. The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.

Waste Management in Propylene Epoxidation Process with the Use of Supercritical Fluid Media

Experimental results on solubility of the styrene, phenol, methylphenylcarbinol, acetophenone, ethyl benzene, propylene glycol and molybdenum as a complex with Trilon B in supercritical CO2 obtained using a dynamic (flow) method are presented. The obtained data are described in the framework of Peng-Robinson equation. The results of the experients on the extraction of organic components from waste formed in the olefin epoxidation process at Nizhnekam-skneftekhim Inc., on the analysis of extract composition, and on the testing of the extract as an epoxidation catalyst are presented. The supercritical water oxidation (SCWO) process of epoxidation process waste was conducted in periodical and continuous mode. The analysis results of reaction product are given. Pilot experiments on dry sediment formation were conducted using Radio Frequency (RF) Inductively Coupled Plasma (ICP) of low pressure.

Photopromoted carbonylation of bromobenzene under ambient conditions

The photopromoted carbonylation of bromobenzene with carbon monoxide catalyzed by inexpensive commercially available cobalt salts [Co（OAc）2, COCl2] was carried out under ambient conditions. The results revealed that methyl benzoate was produced in the presence of basic additives （CH3ONa, NaOAc or （n-C4H9）3N）. The catalytic activity of Co（OAc）2 was higher than that of COCl2. Furthermore, the activity of the carbonylation was greatly improved by addition of acetophenone, e.g. both the yield and selectivity of the ester were increased from 47% to 91% with Co（OAc）2 as catalyst and CH3ONa as additive, while the yield of byproduct benzene from hydrodehalogenation of bromobenzene decreased from 32% to 8%.

Efficient Synthesis of 2,6-Diphenyl-4-arylpyrylium Tetrafluoroborate

Four pyrylium salts, (2,6-diphenyl-4-arylpyrylium tetrafluoroborate, aryl = C6H5, 4-MeO C6H4, 4-Me2NC6H4, 4-NO2C6H4) were synthesized efficiently and economically from acetophenone and substituted chalcones in the presence of borontrifluoride.

High Selective Hydrogenation of Acetophenone Catalyzed by Alumina Supported Platinum Nanoclusters

A new preparation and reduction method of ?Al2O3 supported and PVP stabilized platinum nanoclusters was studied. The catalyst exhibited very high activity and selectivity for acetophenone hydrogenation in isopropanol-KOH solution at 25~60C and P H2=1~5 MPa.

A New Catalyst for Hydrogen Transfer Hydrogenation of Acetophenone

A new C-2-symmetric diamine/diphosphine Ruthenium (II) complex, RuCl2P2N2H4, was used as an excellent catalyst to carry out the catalytic hydrogen transfer reduction of acetophenone. The conversion of acetophenone to 2-phenylethanol was up to 99% under the following reaction conditions: substrate:Ru:(CH3)(2)CHOK = 200:1:12; reaction temperature of 65 degrees C; reaction time of 2 h; normal pressure. A hydride transfer mechanism was also discussed.

REACTION OF α-(1H-1,2,4-TRIAZOL-1-YL)ACETOPHENONE WITH PHENYL ISOTHIOCYANATE

Reaction of α-(1H-1,2,4-triazol-1-yl)acetophenone with phenyl isothiocyanate in the presence of a base and subse- quent alkylation leads to the ketene S,N-acetal(2),(4),(7), (8);thiazolidone(3),thiazolidine(5)and 1,3-thiazine(6),