3875-51-2Relevant academic research and scientific papers
Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
Biermann, Ursula,Metzger, Juergen O.
, p. 10319 - 10330 (2007/10/03)
A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
Energy Well of Diradicals, VII. - Conjugative-Stabilized Trimethylenemethane Derivatives. Geometry Dependance of the Singlet-Triplet Splitting
Roth, Wolfgang R.,Winzer, Markus,Korell, Michael,Wildt, Holger
, p. 897 - 920 (2007/10/02)
For the three 2,1'-bis-allyl diradicals 3-5 the singlet-triplet splitting has been determined by the oxygen-trapping technique.In agreement with theory the value for the planar diradical is large (>14 kcal*mol-1) whereas for the orthogonal geometry the energy gap is small (6.3 kcal*mol-1).In all cases a triplet groundstate is observed.From the rotational barrier of the exo methylene groups in 6 it is shown that the interconversion of the planar and orthogonal singlet states have activation barriers (6-9 kcal mol-1) which are responsible for their kinetic stability.In contrast to 6, where the formation of the orthogonal diradical proceeds by way of the planar diradical 3, the formation of the analogous orthogonal diradical 29 from homofulvene 17 is a concerted process.This difference is an important observation with respect to the fundamental understanding of concerted and non-concerted reactions. - Key Words: Diradicals / Gas-phase kinetics / Oxygen trapping / Dynamic gas chromatography / Rotational barrier, two-step
REACTIONS OF 1-HALO-5-HEXENES WITH ALKYLLITHIUMS. EVIDENCE FOR A PRONOUNCED HALOGEN EFFECT ON THE MECHANISM OF THE METAL-HALOGEN INTERCHANGE REACTION OF PRIMARY ALKYL HALIDES
Bailey, William F.,Patricia, Jeffrey J.,Nurmi, Timo T.
, p. 1865 - 1868 (2007/10/02)
Reaction of t-BuLi with 1-halo-5-hexenes and 1-halo-6-methyl-5-heptenes at -78 gradC has revealed that, whereas 1 deg alkyl iodides are cleanly converted to alkyllithiums in a non-radical process, the corresponding 1 deg alkyl bromides undergo interchange at least partially via a radical-mediated, SET pathway.
Hydrogenolysis of Small Cycloalkanes, X. - Catalytic Hydrogenation of Bicycloalkanes
Stahl, Karl-Johannes,Hertzsch, Winfried,Musso, Hans
, p. 1474 - 1484 (2007/10/02)
Dependent on n different products are obtained from bicycloalkanes by hydrogenation on Pt and Pd/C catalysts: from n = 5 onward only methylcycloalkanes of the same ring size; with n = 4 additionally 2-7 percent of cycloheptane is formed; with n = 3 ring enlargement increases to 5-20 percent and with n = 2 cyclopentane is the only product.Mainly butane is formed from bicyclobutane and no intermediate could be detected.Explanations are attempted.The expected products are produced on hydrogenation of methyl-substituted derivatives and spiroalkanes.
