Catalytic fluorination of dichloromethylbenzene by HF in liquid phase. Preparation of fluorinated building blocks
The selective fluorination by successive Cl/F exchanges of the dichloromethylbenzene, was studied in the presence of HF as the fluorinating agent. The influence of the presence of a catalyst or a basic solvent (such as dioxane, pyridine, tributylphosphate
Microwave-assisted aliphatic fluorine-chlorine exchange using triethylamine trihydrofluoride (TREAT-HF)
Aliphatic fluorine-chlorine exchange reactions can be performed under microwave conditions using TREAT-HF as a mild and selective fluorination reagent. The highly polar TREAT-HF couples efficiently with microwave irradiation and reaction temperatures of 250 °C can be reached within 30 s. Under these conditions dichloromethyl- and trichloromethyl substrates can be converted into the corresponding fluoro analogs within 5 min. In order to prevent corrosion of borosilicate reaction vessel at high temperatures the use of sintered silicon carbide microwave vials is introduced.
Kremsner, Jennifer M.,Rack, Michael,Pilger, Christian,Oliver Kappe
supporting information; experimental part
p. 3665 - 3668
(2009/10/04)
Nitrogen-based halogenating agents and process for preparing halogen-containing compounds
Disclosed are a fluorinating agent represented by the general formula (1): wherein R1to R4are a substituted or unsubstituted, saturated or unsaturated alkyl group or a substituted or unsubstituted aryl group, and can be the same or different; R1and R2or R3and R4can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms; or R1and R3can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms, for example: a preparation process of the fluorinating agent and a process for preparing fluorine compounds by reacting various compounds with the fluorinating agent. The invention has also disclosed that the fluorinating agent is very effective for fluorinating oxygen containing functional compounds.
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(2008/06/13)
MECHANISMS OF FREE-RADICAL REACTIONS. XX. REACTIVITY IN THE FREE-RADICAL HALOGENATION REACTIONS OF ARYLFLUOROALKANES
The free-radical chlorination and bromination of meta- and para-substituted benzyl fluorides and 1,1-difluoro-2-phenylethane and also the chlorination of 1-fluoro-2-arylethanes by phenylchloroiodonium chloride and the bromination of meta- and para-substituted benzyl bromides were studied by the method of competing reactions.In all cases a good correlation is observed between log krel and the Brown ?+ constants.In cases where change in the reactivity in the transition from one reaction series to another is due mainly to the polar effect of the substituent whilethe selectivity is measured in relation to the polar effect direct relationships are observed between the reactivity and the selectivity.
Dneprovskii, A. S.,Eliseenkov, E. V.
p. 711 - 719
(2007/10/02)
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