154035-75-3

Upstream product

• 109-99-9 tetrahydrofuran 
• 1393687-61-0 [(p-tolyl)CaI(tetrahydropyran)₄] 
• 898268-92-3 [(C₆H₅)CaI(tetrahydrofuran)₄] 
• 75-24-1 trimethylaluminum 

Relevant academic research and scientific papers

Arylcalcium iodides in tetrahydropyran: Solution stability in comparison to aryllithium reagents

Reduction of para-substituted iodobenzene in tetrahydropyran (THP) with finely dispersed calcium powder yields arylcalcium iodides of the type [(THP)4Ca(C6H4-4-R)I] with R = CH3 (1), Cl (2), Br (3), I (4), OCH3 (5). A 2-fold insertion of calcium into dihalobenzenes was not observed. The β-naphthylcalcium iodide [(THP)4Ca(β-Naph)I] (6) is also accessible by direct synthesis in THP. The durability of arylcalcium compounds in THP was studied in comparison to that in THF, and a slightly enhanced lifetime in THP at ambient temperature was observed. Furthermore, the relative reactivity and selectivity of 1 and its lithium counterpart [{(THP)2Li}2(μ-Tol)(μ-Br)] (7) in the reaction with THP and THF were studied. α-Metalation and subsequent cycloreversion was the major pathway observed for THF in both cases. In the degradation reaction induced by 7, several byproducts arising from carbolithiation and, surprisingly, from β-metalation reactions were identified, while 1 was found to be more selective. The related [(THP) 2Li(μ-Ph)]2 (9) was prepared and used to unambiguously identify some of the products. In order to verify the formation of benzyllithium as one of the byproducts, an authentic sample of [(dme)Li(μ-CH 2Ph]2 (8) was prepared. In THP, an inversion of the relative reactivity of 1 and 7 was observed and the calcium compound was found to be more reactive than its lithium analogue. The crystal structures of 1-9 were determined by X-ray diffraction studies, and a trans arrangement of the anionic ligands due to electrostatic reasons was observed in case of the hexacoordinated calcium complexes.

Synthesis and properties of calcium tetraorganylalanates with [Me 4-nAlPhn]- anions

Triphenylalane yields in THF or Et2O the corresponding ether complexes [(thf)AlPh3] (1a) and [(Et2O)-AlPh3] (1b). The reaction of these triphenylalanes with phenylcalcium iodide in THF yielded quantitatively [(thf)5CaI][AlPh4] (2), which can be recrystallized from diethyl ether/THF mixtures without ether exchange reactions. The reaction of PhCa(thf)4I with trimethylalane in THF in an equimolar ratio leads to the formation of solvent-separated [(thf) 6Ca][AlMe3Ph]2 (5), which immediately shows ligand redistribution. Therefore, a fractionated crystallization gives [(thf)6Ca][AlMe2Ph2]2 (4) at 4°C, [(thf)4CaI2] at -20°C, and after reduction of the volume of the mother liquor [(thf)6Ca][AlMe3Ph] 2 (5) at -40°C and [(thf)6Ca][AlMe4] 2 (6) at -78°C. The formation of (thf)4Cal2 confirms that a Schlenk equilibrium is operative besides the ligand redistribution reactions. A solution of crystalline [(thf)6Ca] [AlMe2Ph2]2 (4) in THF shows 4 as the major component besides [(thf)6Ca][AlMe3Ph]2 (5) and [(thf)6Ca][AlMePh3]2 (3). With an increasing number of methyl groups the melting points decrease from 210°C for the tetraphenylalanate 2 to 20°C for the tetramethylalanate 6.