2402-78-0Relevant articles and documents
Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 2876 - 2894 (2021/02/01)
Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
Catalyst-Free N-Deoxygenation by Photoexcitation of Hantzsch Ester
Cardinale, Luana,Jacobi Von Wangelin, Axel,Konev, Mikhail O.
supporting information, (2020/02/15)
A mild and operationally simple protocol for the deoxygenation of a variety of heteroaryl N-oxides and nitroarenes has been developed. A mixture of substrate and Hantzsch ester is proposed to result in an electron donor-acceptor complex, which upon blue-light irradiation undergoes photoinduced electron transfer between the two reactants to afford the products. N-oxide deoxygenation is demonstrated with 22 examples of functionally diverse substrates, and the chemoselective reduction of nitroarenes to the corresponding hydroxylamines is also shown.
Production method of 2, 6-dichloropyridine
-
Paragraph 0027-0060, (2020/05/01)
The invention discloses a production method of 2,6-dichloropyridine, which comprises the following steps: introducing pyridine, inert gas and chlorine into a photochlorination reaction device, and carrying out a photochlorination reaction at 150-195 DEG C under an ultraviolet light source which only emits light with the wavelength of 300-460nm.
Pyridine liquid phase light chlorinated preparation 2, 6 - dichloro pyridine method
-
Paragraph 0012-0035, (2019/07/05)
The invention relates to a kind of the trifluoromethyl chlorobenzene as the solvent, 2 - chloro pyridine and chlorine as the raw material, process for preparing the product purity ≥ 99.0% of 2, 6 - dichloro pyridine production method, in order to 2 - chloro pyridine, chlorine as the starting material, trifluoromethyl chlorobenzene as the solvent, in the 150 °C -200 °C temperature, ultraviolet light irradiation under the continuous feed of the liquid phase chlorination reaction, to obtain the chloride, wherein the chloride in pyridine 2, 6 - dichloro pyridine content ≥ 97%, chlorinated rough steaming, crystallization separation or distillation purification process, get the purity ≥ 99.0% of 2, 6 - chlorinate, yield is greater than 90%. Advantages: produced by the reaction of 2, 6 - dichloro pyridine high selectivity, adding solvent to the reaction device overcomes the problem of exhaust gas easy blockage of the pipe, reaction process is easy to control, help to realize commercial process.
Method for preparing 2,6-dichloropyridine by pyridine liquid-phase photochlorination
-
Paragraph 0016-0027; 0028; 0029; 0031, (2019/01/23)
The invention relates to a method for preparing 2,6-dichloropyridine with product purity greater than or equal to 99.0% by using chlorotrifluoromethylbenzene as a solvent for a reaction between pyridine and chlorine. The preparing process comprises the steps as follows: by using the pyridine and the chlorine as initial raw materials and using the chlorotrifluoromethylbenzene as the solvent, continuously performing a chlorination reaction on the pyridine and the chlorine under the irradiation of ultraviolet light; and cooling a chlorination reaction product and the solvent to obtain pyridine chloride solution. The method has the advantages that 1, a precedent of directly preparing the 2,6-dichloropyridine in a high selectivity mode by a liquid-phase photochlorination reaction is set, and not only is the 2,6-dichloropyridine product with purity greater than or equal to 99.0% obtained, but also the method is easy for industrial production; and 2, not only is recycling of the separation solvent in the preparing process of the 2,6-dichloropyridine product with purity greater than or equal to 99.0% implemented, but also the aims of low pollution, low energy consumption and low cost in the preparing process are fulfilled.
Method and production line for preparing 2,6-dichloropyridine through gas phase photochlorination of pyridine
-
Page/Page column 5-7, (2019/10/29)
The present invention relates to a method for preparing 2,6-dichloropyridine with product purity greater than or equal to 99.0% through gas phase photochlorination of pyridine by using trifluoromethyl chlorobenzene as a solvent for reaction between pyridine and chlorine gas. Gasified pyridine and heated chlorine gas are enabled to continuously experience chlorination reaction under irradiation of ultraviolet light by using gasified pyridine and heated chlorine gas as starting materials and using heated trifluoromethyl chlorobenzene as a solvent, and a gas phase reaction product and the solvent are cooled to obtain pyridine chlorination solution. Advantages: firstly, it pioneers the precedent of direct and high-selectivity preparation of 2,6-dichloropyridine through gas phase photochlorination, and not only can the 2,6-dichloropyridine product with purity greater than or equal to 99.0% be obtained, but also industrial production is facilitated; and secondly, the selectivity of pyridine chlorination is high, the chlorination solution is subjected to crude distillation to separate high-boiling-point substances, the crude distillate is subjected to cooling crystallization or rectification to separate the solvent, the solvent is reused, and not only can the 2,6-dichloropyridine product with purity greater than or equal to 99.0% be obtained, but also the purposes of no pollution, low energy consumption and low cost can be realized.
An Improved Rapid and Mild Deoxygenation of Amine N-oxides
Rajesh
, p. 486 - 491 (2017/12/29)
An improved mild and selective method for the deoxygenation of a variety of amine N-oxides has been carried out in the presence of silica gel under mild conditions at room temperature to afford corresponding amines in relatively good yields without purification. The reaction is tolerant of a variety of functional groups such as hydroxyl, ester, acid, carbonyl, and cyano groups, as well as halogens. This method would be of great utility to synthesize various pyridines and amines easily.
The radical reaction from a fluorine-containing compound
-
Paragraph 0033-0034, (2017/01/05)
PROBLEM TO BE SOLVED: To provide a radical reaction substitute solvent for carbon tetrachloride which has been used heretofore as a radical reaction solvent. SOLUTION: A chain fluorine-containing hydrocarbon represented by formula (1): CmH2m+2-nFn(wherein m is an integer of 3-10 and n is an integer of 1 to 2m+1) or a cyclic fluorine-containing hydrocarbon represented by formula (2): CpH2p-qFq(wherein p is an integer of 3-10 and q is an integer of 1 to 2p-1) is used as a solvent for various radical reactions. COPYRIGHT: (C)2011,JPO&INPIT
Copper-catalyzed conversion of aryl and heteroaryl bromides into the corresponding chlorides
Feng, Xiujuan,Qu, Yiping,Han, Yanlei,Yu, Xiaoqiang,Bao, Ming,Yamamoto, Yoshinori
supporting information, p. 9468 - 9470 (2012/10/29)
An efficient method for the synthesis of aryl and heteroaryl chlorides is described. The reactions of aryl and heteroaryl bromides with tetramethylammonium chloride proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding chlorides in satisfactory to excellent yields.
Reduction of amine N-oxides by diboron reagents
Kokatla, Hari Prasad,Thomson, Paul F.,Bae, Suyeal,Doddi, Venkata Ramana,Lakshman, Mahesh K.
experimental part, p. 7842 - 7848 (2011/12/01)
Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis- (pinacolato)- and in some cases bis(catecholato)diboron [(pinB)2 and (catB)2, respectively]. Reductions occur upon simply mixing the amine N oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)2 was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)2, triethylborane reduced alkylamino-N oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)2 has been probed by 1H and 11B NMR. (Figure presented) ; 2011 American Chemical Society.
