Catalytic hydrogen transfer over magnesia. Part XXV. Liquid and vapor phase reduction of ketoesters

Abstract

The reactivity of two series of compounds: alkyl x-oxoalkanoates (x = 2, 3, 4 and 6), and alkyl x-phenyl-y-oxoalkanoates (y = 2 and 4) has been studied in the catalytic transfer hydrogenation (CTH) over magnesium oxide as the catalyst. The catalytic tests have been performed either in liquid or vapor phase with secondary alcohols (2-propanol to 2-octanol) as hydrogen donors. A strong diminution of reactivity of the ketoesters in CTH has been observed, in contrast to simple aliphatic or aralkyl ketones. The occurrence of transalcoholysis between ketoesters and alcohols used as hydrogen donors resulted in the formation of new ketoesters as side products. The hydroxoesters, i.e. the products of the CTH reaction, have been obtained with only moderate to good yields (up to 50 %). It has been found that in the CTH of ketoesters with the carbonyl group in a c position, such as alkyl levulinates and benzoylpropionates, the appropriate lactones (c-valerolactone and 5-phenyl-c-valerolactone) have been formed.

Catalytic Activity of High-Surface-Area Amorphous MgO Obtained from Upsalite

“…Therefore, the effect of the discrepancy in the temperatures overlapped with the effect of the donor structure. The separation of the effects led to the conclusion that the alcohol with the longer chain was a poorer donor when tested at the lower temperature, as described by us in [19]. This effect was not tested again in the current study.…”

“…Catalysts 2021, 11, x FOR PEER REVIEW 7 of 14 lower temperature, as described by us in [19]. This effect was not tested again in the current study.…”

“…For quantitative determination of the compositions of post-reaction mixtures, t-butylbenzene was used as an internal standard. The details of measurements are given elsewhere [19,48].…”

“…The high basicity of the MgO surface makes it an attractive catalyst that is used in numerous chemical processes, such as the transesterification of fats with methanol to produce fatty acid methyl esters (FAME) [12][13][14], the alkylation of phenol with methanol to 2,6-dimethylphenol [15,16], or the isomerization of a carbon-carbon double bond in the Shell Higher Olefin Process (SHOP) [17,18]. It is noteworthy that magnesium oxide is one of the most active metal oxides in the transfer hydrogenation reaction to carbonyl compounds using alcohols as hydrogen donors [19,20], although many other transfer hydrogenation catalysts continue to be widely investigated [21][22][23][24][25]. The reaction was shown to occur on supported metal and alloy catalysts, such as Au, Pt, Pd, Ru, Ag-Pd, etc.…”

Highly Efficient Nanosized Mesoporous CuMgAl Ternary Oxide Catalyst for Nitro-Alcohol Synthesis: Ultrasound-Assisted Sustainable Green Perspective for the Henry Reaction

“…Metal oxides synthesized from hydrotalcite-like structures are considered as nanosized mesoporous solid-base catalysts, which have unique features with respect to crystallite size, morphology, and surface area, as well as high catalytic efficiency in various catalytic reactions. , For example, in the last decade, CuO/Al 2 O 3 obtained from hydrotalcites has been considered an efficient catalyst for the synthesis of alcohols . Furthermore, MgO has strong Lewis basic sites due to the presence of O 2– ions and has been used as an efficient catalyst for the hydrogenation of alkyl ketones …”