70547-85-2

Upstream product

• 103-63-9 1-phenyl-2-bromoethane 
• 106020-40-0 1,3,6-triphenyl-3-hexanol 
• 106020-32-0 tris(benzothieno)<3,2-b:2',3'-d:2'',3''-f>oxepin 
• 100-42-5 styrene 
• 637-59-2 1-Bromo-3-phenylpropane 
• 1083-30-3 dihydrochalcone 
• 614-47-1 1,3-diphenyl-propen-3-one 

Relevant academic research and scientific papers

Comparison of the regiochemical behavior of zirconium and hafnium in the polyinsertion of styrenes

The hafnocene-based catalyst ethylenebis(1-indenyl)hafnium dichloride/methylalumoxane, as well as its zirconium analogue, is able to oligomerize styrene, p-methylstyrene, and p-tert-butylstyrene in the presence of hydrogen to produce hydrooligomers. The c

Regiochemistry of the styrene insertion with CH2-bridged ansa-zirconocene-based catalysts

Methylenebis(indenyl)zirconium dichloride substituted in C(3), activated by methylalumoxane, is able to give polystyrene and ethylene-styrene copolymers. In this study hydrooligomers, whose structure, determined by 13C NMR and GC-MS techniques, gives information about the regiochemistry and the stereochemistry of styrene insertion, have been purposefully prepared. The regiochemistry of the styrene insertion is related to the encumbrance of substituents in C(3). rac-[Methylene-(3-R-1-indenyl)2]ZrCl2 with R = H, CH3, or CH2CH3 induces a prevailingly secondary styrene insertion into the zirconium-carbon bond. With increasing the substituent's steric hindrance (R = CH(CH3)2), regiochemistry inversion occurs and the primary insertion becomes prevailing. The analysis of ethylene-styrene copolymers obtained in the presence of the different catalysts allows confirming the correlation between regiochemistry and comonomers' reactivity. Besides, also the stereospecificity can be evaluated from the structure of the hydrotrimers, when the insertion is primary. Whereas the isospecificity in the absence of substituents (secondary insertion) and in the presence of the tert-butyl substituent (primary insertion) is well-known, a surprising syndiospecificity is observed when the indenyl ligand bears the isopropyl substituent in C(3).

CYCLOCONDENSATION OF 3(2H)-BENZOTHIOPHENONE AND OXIDATION PRODUCTS OBTAINED DURING THESE REACTIONS

The cyclocondensation of 3(2H)-benzothiophenone under acidic conditions has been studied.The symmetrical cyclotrimer tris(benzothieno)benzene was formed and under certain conditions also a rearranged cyclotrimer, tris(benzothieno)benzene.The formation of cyclotrimers was accompanied by oxidative coupling products involving the initially formed dimeric compound, 3-hydroxy-2,3-bibenzothienyl.During several of these reactions, a novel heterocycle, tris(benzothieno)oxepin, was formed.The products were studied by mass spectrometry and fragmentation pathways were determined by a linked scanning technique.

Carbanion Rearrangements by Intramolecular 1,ω Proton Shifts, III. The Reaction of 2-, 3-, 4-, and 5-Phenylalkyllithium Compounds

Upon addition of THF to a solution of 4-phenylbutyllithium (2) in diethyl ether a rapid intramolecular 1,4 proton shift takes place with the formation of 1-phenylbutyllithium (5).Similarly, although somewhat more slowly, 5-phenylpentyllithium (82) rearranges to 1-phenylpentyllithium (83) via 1,5 proton transfer.The corresponding rearrangements by 1,2 or 1,3 hydrogen shifts, however, starting with 2-phenylethyllithium (1) and 3-phenylpropyllithium (54), respectively, were not detected.With 3-phenylpropyllithium (54) a slow intramolecular 1,5 transfer an ortho proton is observed instead, yielding o-propylphenyllithium (100).The corresponding 1,6 shift with 4-phenylbutyllithium (2) was also detected in a minor amount in addition to the 1,4 proton shift already mentioned.There is no indication, however, for a 1,4 transfer of an ortho proton in 2-phenylethyllithium (1).The reaction products in this case can be exclusively explained by intermolecular transmetallation reactions.All ω-phenylalkyllithium compounds under investigation show interesting side and secondary reactions being rather different in deuterated solvents and in deuteriumfree solvents, respectively, due to the isotope effects.The analysis of the products is accomplished by 1H-NMR spectroscopy and, after derivatization, with the help of a GC-MS-combination.Stereoelectronic reasons are made responsible for the failure of the intramolecular 1,2 and 1,3 proton shift in these systems.