Alkyl‐Branched Fatty Compounds: Hydro‐Alkylation of Non‐Activated Alkenes With Haloalkanes Mediated by Ethylaluminum Sesquichloride

Abstract

The general method for the cationic hydro-alkyl addition to the nonactivated C5 5C double bond of alkenes mediated by ethylaluminum sesquichloride (Et 3 Al 2 Cl 3 ) has been importantly improved and simplified by using haloalkanes (primary, secondary, tertiary) instead of alkyl chloroformates as alkylating agent and performing the reaction without any additional solvent. The protocol is especially suited to perform the hydro-alkylation of internal double bonds. Reaction of the haloalkane with Et 3 Al 2 Cl 3 gives an alkyl cation which is added to the alkene; hydride transfer from Et 3 Al 2 Cl 3 to the adduct carbenium ion gives the saturated addition product. Primary halo alkanes give the same addition product as the respective secondary halo alkane because of 1,2-H shift yielding the secondary carbenium ions. In the case of 1-alkenes triethylsilane has to be used as additional hydride donor to avoid di-and oligomerization. Special interest has been focused on alkylation of unsaturated fatty compounds, which are important renewable feedstocks, mostly (Z)-configured such as methyl oleate, high oleic sunflower oil, neopentyl glycol dioleate, but also (E)-configured, that is, dimethyl (E)-icos-10-enedioate, and with terminal double bond such as methyl 10-undecenoate. The respective alkyl branched fatty compounds were obtained after simple work-up with excellent to good yields. The protocol was scaled up without problems to >0.5 mol.

Fatty Acids and their Derivatives as Renewable Platform Molecules for the Chemical Industry

“… [59] The protocol for the synthesis of well‐defined alkyl‐branched oleochemicals was considerably improved by using haloalkanes instead of chlorocarbonates [4] to give the hydroalkylation products in excellent to good yields (Scheme 11 ). [60] Importantly, the reaction protocol was scalable (>500 g 2 b ) and was also applied to substrates with two or more double bonds as well as to triglycerides.…”

“…Et 3 Al 2 Cl 3 -mediated hydroisopropylation of 2b. [60] Scheme 12. Rh-catalyzed cycloaddition of 4a and maleic anhydride.…”

Fettsäuren und Fettsäurederivate als nachwachsende Plattformmoleküle für die chemische Industrie

“…[59] Die Vorschrift für die Synthese von klar definierten alkylverzweigten Oleochemikalien wurde durch die Verwendung von Halogenalkanen statt von Chlorformiaten wesentlich verbessert [4] und erlaubt die Isolierung der Hydroalkylierungs-Produkte in ausgezeichneten bis guten Ausbeuten (Schema 11). [60] Es ist von Bedeutung, dass sich die Vorschrift als skalierbar erwies (> 500 g 2 b) und auch auf Substrate mit zwei oder mehr Doppelbindungen wie auch auf Triglyceride angewendet werden konnte.…”

“…Et 3 Al 2 Cl 3 -vermittelte Hydroisopropylierung von 2b. [60] Schema 12. Rh-katalysierte Cycloaddition von 4a und Maleinsäureanhydrid.…”

Synthesis of novel chemicals from cardanol as a product of cashew nutshell processing

“…Examples for such transformations are the epoxidation, dihydroxylation, oxidative cleavage, metathesis, hydroformylation, isomerizing hydroformylation, hydroaminomethylation, and isomerizing alkoxycarbonylation of the olefin moiety in the hydrocarbon chain (Seidensticker, Vorholt, & Behr, ). Recent contributions to this chemistry report the hydroalkylation (Biermann & Metzger, ) and the Wacker oxidation (von Czapiewski & Meier, ) of methyl oleate.…”