Reactions of free aluminum atoms. Direct syntheses of organoaluminum compounds

Abstract

aluminum atoms in the substrate and the fact that there is no change of products during warm-up (vide infra) suggest that only one aluminum atom is involved. Work in progress may indicate this feature of the product structure. However, the total number of attachments per aluminum atom is 2.7. Thus the main course of the reaction is addition of aluminum(s) to the double bond to make 1,2-dialuminoalkanes. The C6 products are 1,4-dialuminoalkanes formed, formally, by coupling of 1-alumino-2-propyl radicals, mainly, and 2-alumino-1-propyl radicals to a minor extent.The major reactions of aluminum atoms with olefins have been described as direct addition, rather than primary formation of AI-H linkages. The final product contains little AI-H (low yield of HD). Had AI-H's been a primary product which then added to propene, a propylaluminum would have been the product, which on deuterolysis would have given a substantial yield of C3H7D. The 4% yield of C3H7D is attributed to protium inclusion from the glass surfaces, etc.The process of product formation has been demonstrated to occur prior to warm-up of the cocondensate. The cocondensate on a cesium bromide window cooled to liquid nitrogen temperature shows the same products are present (infrared spectra) prior to warm-up as after warm-upa6 Thus the reactions go to completion at the low temperature. Further, there is no absorption in the 1900-1 7 0 0 -~m -~ region (characteristic of AI-H linkages), but strong absorptions in the 700-600-cm-1 region, characteristic of aluminum-alkyl bonds. The absence of AI-H absorption accords with the absence of significant amounts of H D on deuterolysis (3% yield).A blank reaction was carried out to learn if cleansurface condensed forms of aluminum would also react with propene. Aluminum atoms (2.0 mmol) were cocondensed with propane, a hydrocarbon with essentially the same melting point as propene. After shutting off the supply of aluminum vapor, propene was condensed on the matrix. In contrast to the work described above, the matrix was black as a result of self-condensation of aluminum. The residue left after pumping off unreacted hydrocarbon was deuterolyzed with D,O. The major product is DP, 25% yield. Propane and propene are obtained in 5 and 4% yields, respectively, the latter being 100% do, the propane 35% dl and 13% dz. Hexanes, if present, were formed in yields less than 0.05%, the detection limit. It is clear that the reactions of free aluminum atoms are not those of the bulk metal, regardless of the state of subdivision.The 1-and 2-butenes show analogous behavior from which one learns the additional ambiguous feature that either of the 2-butenes gives nearly the same mixture of mesoand d,l-2,3-dideuteriobutanes.Addition of aluminum atoms to 1,3-butadiene produces 3,4-dideuterio-l-butene as the major product on deuteriolysis.The reactions of platinum' or nickel8 with propene (6) Work done in cooperation with Professor I. C. Hisatsune, The (7) P. S. Skell and J.

Gas‐phase rate coefficients for the reactions of O(3P), S(3P), Se(3P), and Te(3P) with alkenes: Application of perturbation frontier molecular orbital theory, correlations, and structure–activity relations (SARs)

“…The decompo‐ sition of these intermediates is dominated by an H‐atom loss to form the propargyl radical as well as 1‐, 3‐methylpropargyl, and 1,3‐butadienyl‐2 radicals. It has also been shown that reactions of Al atoms with unsaturated organic molecules are not restricted to adduct formation processes involving π‐interactions 21, and both σ‐ and π‐bonded species are found to be formed in reactions of Al atoms with unsaturated hydrocarbons 22,23. There is thus evidence that is suggestive of the existence of a different mechanism for these reactions.…”

Boron, Aluminum, Gallium, Indium, and Thallium (Group IIIA)

“…There seems little doubt that aluminum alkyls and dialuminoalkanes are formed in this process, and matrix-isolation studies at -196°C support this claim. 58 Thus, σ-C-Al bonds are formed at -196°C and above. Also, some C-C coupling is induced.…”

“…Skell and co-workers [56][57][58] codeposited Al atoms with propene, and the resultant organoaluminum mixture was hydrolyzed with D 2 0 to yield deuterated propane, 2,3-dimethybutane, 2-methylpentane, and traces of rc-hexane. Aluminacyclopropane radicals have been proposed…”

Electron spin resonance studies of the reactions of aluminium atoms with some alkenes in a rotating cryostat

“…6. It was possible by simulation methods to assign transitions to a P-substituted t-butyl [a,(6) = 22.5 G and a&) = 11.3 GI, labelled with open circles, and 2-methylallyl [a, ( 1,3, endo) = 13.8 G, a,( 1,3, exo) = 14.7 G, a,(CH,) = 3.2 GI. There were additional features in the spectrum which have, as yet, eluded assignment.…”