- COMPARISON OF ANALYTICAL PYROLYSIS TECHNIQUES IN THE CHARACTERIZATION OF CHITIN.
-
The results of various analytical pyrolysis techniques with on-line and off-line detection have been examined with respect to characteristicity and contents of information, using chitin as a model polymer. Curie-point pyrolysis-low-energy electron impact mass spectrometry (cPy-EIMS), using normal and preheated telescopic glass tube sample holders, was applied, as well as Curie-point pyrolysis-gas chromatography/mass spectrometry, with electron impact ionization and chemical ionization (cPy-GC/EIMS, cPy-GC/CIMS).
- van der Kaaden,Boon,de Leeuw,de Lange,Schuyl,Schulten,Bahr
-
-
Read Online
- Spectroscopic and Crystallographic Characterization of the R3N+?C?H???X Interaction
-
As appreciation for nonclassical hydrogen bonds has progressively increased, so have efforts to characterize these interesting interactions. Whereas several kinds of C?H hydrogen bonds have been well-studied, much less is known about the R3Nsu
- Capilato, Joseph N.,Harry, Stefan A.,Lectka, Thomas,Siegler, Maxime A.
-
-
- Preparation method of 2,3-dichloropyridine
-
The invention provides a preparation method of 2,3-dichloropyridine. The 2,3-dichloropyridine is prepared by a one-pot method, pyridine alkyl ester serves as a raw material, and synthesis is conductedby a mode of performing chlorination, performing hydrolysis and performing chlorination again; the chlorination is substitution reaction, substitution on a benzene ring is relatively easy, the alkylester group can protect the site of the first-time chlorination reaction to be at 2 position, the hydrolysis reaction is mild in condition and rapid in reaction compared with the prior art, the second-time chlorination is to substitute the hydroxyl, the reaction is easy and the reaction condition is relatively mild. The preparation method provided by the invention is simple in operation, few threewastes are generated in the production process, requirements on equipment are low and the yield is high.
- -
-
Paragraph 0048-0049
(2018/06/15)
-
- Structures, Lewis Acidities, Electrophilicities, and Protecting Group Abilities of Phenylfluorenylium and Tritylium Ions
-
The isolation, characterization, and the first X-ray structures of a fluorenylium ion and its Lewis adducts with nitrogen- and phosphorus-centered Lewis bases are reported. Kinetics of the reactions of a series of fluorenylium ions with reference π-, σ-, and n-nucleophiles of various sizes and nucleophilicities allowed the interplay between electronic and structural parameters on the electrophilicities of these planarized tertiary carbenium ions to be elucidated. Structure–reactivity correlations and extensive comparisons of their reactivities with those of di- and triarylcarbenium ions are described. Quantitative determination of the electrofugalities of fluorenylium ions revealed to which extent they are complementing tritylium ions as protecting groups and how their tuning is possible. Determination of the equilibrium constants of the Lewis adducts formation between pyridines of calibrated Lewis basicities and phenylfluorenylium and tritylium ions allowed the determination of their Lewis acidities and to showcase the potential of these carbon-centered Lewis acids in catalysis.
- Follet, Elsa,Mayer, Peter,Berionni, Guillaume
-
supporting information
p. 623 - 630
(2017/01/18)
-
- Facile esterification of alcohols with 2-Acyl-4,5-dichloropyridazin-3(2 H)-ones under Friedel-Crafts conditions
-
This paper describes the esterification of aromatic and aliphatic alcohols by using 2-acyl-4,5-dichloropyridazin-3(2H)-ones as an acyl source under Friedel-Crafts conditions. Twelve alcohols were reacted with four 2-acyl-4,5-dichloropyridazin-3(2H)-ones in the presence of AlCl3 in tetrahydrofuran at room temperature to give the corresponding esters in moderate to excellent yields. Thus, 2-acylpyridazin-3(2H)-ones serve as good and atom-economic acyl sources for the esterification of aromatic alcohols under Friedel-Crafts conditions, representing a rapid, practical, and efficient method of esterification. Georg Thieme Verlag Stuttgart. New York.
- Kim, Bo Ram,Sung, Gi Hyeon,Ryu, Ki Eun,Yoon, Hyo Jae,Lee, Sang-Gyeong,Yoon, Yong-Jin
-
p. 1909 - 1915
(2014/08/18)
-
- Catalyst-free esterification of alcohols using 2-acyl-4,5- dichloropyridazinones under microwave conditions
-
Efficient and green esterification is of great importance. In this work, we demonstrate the catalyst-free esterification of alcohols by their reaction with 2-acyl-4,5-dichloropyridazin-3(2H)-ones under microwave irradiation. Aliphatic and aromatic alcohols were converted into the corresponding esters in good to excellent yields under microwave irradiation in solvent or solvent-free conditions. It is noteworthy that the reaction is catalyst-free, atom-economic, and rapid and that the process is inexpensive.
- Kim, Bo Ram,Sung, Gi Hyeon,Lee, Sang-Gyeong,Yoon, Yong Jin
-
supporting information
p. 3234 - 3237
(2013/04/24)
-
- Rapid and Ecofriendly Esterification of Alcohols with 2-Acylpyridazinones
-
Atom-economical esterification is of great importance in green chemistry. In this work, we demonstrated the catalyst and additive free esterification of alcohols by their reaction with 2-acyl-4,5-dichloropyridazin-3(2H)- ones without solvent at 100 oC. Aliphatic and aromatic alcohols were converted into the corresponding esters in good to excellent yields. It is noteworthy that the reaction is solvent-free, atom-economic, easy-workup, and rapid and that the process is inexpensive.
- Kim, Bo Ram,Sung, Gi Hyeon,Ryu, Ki Eun,Kim, Jeum-Jong,Yoon, Yong-Jin
-
p. 3410 - 3414
(2014/01/06)
-
- Heterogeneous Baeyer-Villiger oxidation of ketones with H2O2/nitrile, using Mg/Al hydrotalcite as catalyst
-
We synthesized a magnesium-aluminium hydrotalcite and used it as a catalyst in the Baeyer-Villiger (BV) oxidation of cyclohexanone with a mixture of 30% aqueous hydrogen peroxide and benzonitrile as oxidant. The hydrotalcite proved an excellent catalyst for the process. The influence of experimental variables was examined in depth in order to bring the working conditions as close as possible to those usable on an industrial scale. We optimized the cyclohexanone/hydrogen peroxide/benzonitrile proportion and used various nitriles, solvents and amounts of catalyst, benzonitrile and methanol proving the most effective nitrile and solvent, respectively, for the intended purpose. The reaction was found to occur to an acceptable extent with other carbonyl compounds as substrates; by exception, α,β-unsaturated carbonyl compounds provided poor results by effect of their undergoing competitive epoxidation of their double bonds.
- Llamas, Rafael,Jiménez-Sanchidrián, César,Ruiz, José Rafael
-
p. 1435 - 1439
(2007/10/03)
-
- SnCl4-promoted ethenylation reaction of hydroxylated heteroarenes
-
Reaction of hydroxylated heteroarenes and acetylene in the presence of SnCl4 and Bu3N (or Et3N) gives the corresponding ethenylated arenes. The reaction takes place at the neighboring position of the hydroxy group, and is applicable to quinolines, an isoquinoline, pyridines, and N-trifluoromethanesulfonylated indoles provided that the optimized conditions for the ethenylation and workup are employed.
- Akamatsu, Kensuke,Amemiya, Ryo,Yamaguchi, Masahiko
-
p. 1839 - 1847
(2007/10/03)
-
- Synthesis of alkyl heteryl ethers from acetates under interphase catalysis conditions in a liquid/solid system
-
The reaction of acetates of heterocyclic alcohols with alkyl halides in the two-phase catalytic system of solid KOH/C6H6/18-crown-6 at room temperature leads selectively to the formation of the corresponding heterocyclic ethers in 32-93% yield. 1998 Plenum Publishing Corporation.
- Abele,Abele,Gaukhman,Lukevics
-
-