Condensations by Sodium. XXX. The Metalation of Olefins and the Preparation of β,γ-Unsaturated Acids

Abstract

Olefins can be converted by amylsodium to alkenylsodium reagents. This reaction, just observed, is important in a preparative way because the products, when carbonated, yield j3,y-unsaturated acids which, in most cases, have not been prepared hitherto. The work furnishes also a basis for a comparison of the relative hydrocarbo acidities' of the olefins and of the relative acidities a t various positions in an olefin, and shows that an alkyl group reduces this acidity even as it does in aromatic compounds. Finally, this acidity appears to be closely related to the general reactivity of the olefins in reactions where a labile hydrogen atom is involved, because the compounds primarily produced by polymerization of olefins in acid solution can be predicted from the data of relative acidities, as determined by the alkaline reagents.Metalation of Olefins.-The formation of alkeriylsodium compounds takes place so easily that its non-observance in our previous studies now appears surprising. Any interchange that did occur in the past has, however, been extremely slight, since the quantity of olefin present has been very low, the effectiveness of stirring has been much less than a t present and the reaction time has been short. Attention was first directed to this new reaction by a preparation of amylpotassium, analogous to that of amylsodium. The product, after carbonation, contained a trace of unsaturated acids which boiled within the same range as caproic acid. The new products were derived from the reaction shown below between CH?=CHCH (IC) ClHo and KCH=CHCjH7 amylpotassium and 1-pentene, an olefin which happened to be present in the reaction mixture because of a disproportionation in the reaction of amyl chloride with amylpotassium which occurred during the preparation of the latter by addition of aniyl chloride to metallic potassium. Amylsodium was then found to react with the olefin as did amylpotassium provided a sufficient quantity of the hydrocarbon was present and the reaction was given time for completion.Isobutene is readily attacked by amylsodium. The product, after carbonation, is the hitherto unreported P-methylvinylacetic acid, as shown by analysis of the p-bromophenacyl ester derivative, and by isomerization of the acid under the influence of alkali to the known @,@-dimethylacrylic acid. Evidence that a dicarboxylic acid, @-CjE€iiI( + GHie + (1) Morton, Chem. Rm., 35, 1 (1944) H2C=C(-CHoCOzNamcthyleneglutaric acid, H2C=C (CK2COOH)a, the result of dimetalation, is present in a higher boiling fraction, is given by ozone cleavage to formaldehyde stid acetonedicarboxylic acid. By a similar series of reactions propene gives vinylacetic acid, though in smaller yield than the niethylvinylacetic acid. This metalation occurs readily also but a cornparison of. the relative activities of propene and isobutene is difficult to make because propene is so volatile. Propene shows a smaller amount of interchange with benzylsodium than with amylsodium, and this fact accords with the view that the latter is a salt of a weak...

Synthesis and Structures of [(Trimethylsilyl)methyl]sodium and ‐potassium with Bi‐ and Tridentate N‐Donor Ligands

“…However, the preparation and characterisation of these highly polar (more so than lithium or magnesium) compounds is complicated by several possible side reactions, including most notably metalation of the organic solvent,5 β‐elimination6 or self‐metalation 7. Their preparations could be achieved in aliphatic hydrocarbons through halogen/metal exchange8 (direct synthesis), reaction of alkylmercury compounds with alkali metals (transmetalation)9 or reaction of alkyllithium compounds with alkali metal tert ‐butoxides (metal/metal exchange) 10. Because of their low stability and low solubility in hydrocarbons, few alkylsodium and ‐potassium compounds have been structurally characterised.…”

Inter-polymerization of Isobutene and 2-Methyl-2-butene Using an Alumina-Silica Catalyst. Composition of the Hydrogenated Nonenes

“…In all of our considerations of acid catalyzed polymerizations we have found the mechanism suggested by Whitmore to be more generally valid than the mechanisms or schemes suggested by others. [29][30][31][32][33][34]…”

Alkyl and Aryl Derivatives of the Alkali Metals: Useful Synthetic Reagents as Strong Bases and Potent Nucleophiles. 1. Conversion of Organic Halides to Organoalkali-Metal Compounds

“…This procedure was reported to work well in the preparation of amylpotassium by reaction of amyl chloride with potassium sand, but the yield, as indicated by the yield of caproic acid after reaction with dry ice, was considerably lower. 75 Others have reported the utility of this alkylpotassium synthesis. 76 However, later work by R. A. Finnegan 77 claimed that the preparation of alkylpotassium compounds (n-C 3 H 7 K, n-C 4 H 9 K, n-C 5 H 11 K) by the standard n-C 5 H 11 Na procedure was much more complex.…”

“…This procedure was reported to work well in the preparation of amylpotassium by reaction of amyl chloride with potassium sand, but the yield, as indicated by the yield of caproic acid after reaction with dry ice, was considerably lower . Others have reported the utility of this alkylpotassium synthesis …”