Description of the structure-chemoselectivity relationship in the transfer hydrogenation of α,β-unsaturated aldehydes and ketones with alcohols in the presence of magnesium oxide

Gliński, Marek; Ulkowska, Urszula

doi:10.1016/j.apcata.2018.02.001

Cited by 6 publications

(11 citation statements)

References 23 publications

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“…In the case of the highest temperature, the SOL: UOL ratio was 1 with ethanol and 4 for 2-propanol. This was probably caused by the fact that 2propanol is a better hydrogen donor than ethanol, as was previously observed for crystalline MgO [20]. In the case of 2-n-propylacrolein, the reverse order was observed [20].…”

Section: Resultsmentioning

confidence: 54%

“…It can be seen that, as in the case of crystalline MgO, the amorphous MgO, higher conversion of acrolein was attained when ethanol was used as the hydrogen donor. A discussion regarding these two hydrogen donors in THR to acrolein was conducted by us in a previous study [20]. In the case of this reaction, the potential products were the saturated aldehyde, saturated alcohol, and unsaturated alcohol, which was the desired product due to the fact it is more valuable than the other two products [20].…”

Section: Resultsmentioning

confidence: 99%

“…A discussion regarding these two hydrogen donors in THR to acrolein was conducted by us in a previous study [20]. In the case of this reaction, the potential products were the saturated aldehyde, saturated alcohol, and unsaturated alcohol, which was the desired product due to the fact it is more valuable than the other two products [20]. It was favorable that under the reaction conditions, the unsaturated alcohol was the main product with yields of over 60% at 573 and 623 K. The conversion increased with temperature throughout the entire studied range.…”

Section: Resultsmentioning

confidence: 99%

“…It is noteworthy that the contribution of the saturated alcohol was higher when 2-propanol was used as the hydrogen donor than in the tests with ethanol in the entire temperature range (Figure 8a,b). Our previous studies showed that with crystalline MgO as the catalyst, the presence of a substituent in the number 2 position in an acrolein derivative enhances its chemoselective reduction to the unsaturated alcohol [20]. Therefore, hydrogen transfer in the presence of the obtained high-surface, amorphous MgO between ethanol or 2-propanol and 2-n-propylacrolein was also studied.…”

Section: Resultsmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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The first aim of the research was to synthesize a pure Upsalite, which is an amorphous form of MgCO3, by modifying a procedure described in the literature, so that it would be the precursor of a high-surface, amorphous magnesium oxide. The results indicate that within the studied reaction conditions, the type of alcohol used as the reactant has the most pronounced effect on the yield of reaction. From the two alcohols that led to the highest yield of Upsalite, methanol gave a substantially larger surface area (794 vs. 191 m2 g−1). The optimized synthesis conditions of Upsalite were used to obtain MgO via thermolysis, whose activity in the transfer hydrogenation reaction (THR) from ethanol, 2-propanol and 2-pentanol to various carbonyl compounds was determined. The optimal conditions for the thermolysis were as follows: vacuum, T = 673 K as the final temperature, and a heating rate of 2 deg min−1. The high-surface, amorphous magnesia (SBET = 488 m2 g−1) was found to be a very selective catalyst to 4-t-butylcyclohexanone in THR, which led to a diastereoselectivity of over 94% to the E-isomer of 4-t-butylcyclohexanol for more than 3 h, with conversions of up to 97% with either 2-propanol or 2-pentanol as the hydrogen donor. In the case of acrolein and 2-n-propylacrolein being used as the hydrogen acceptors, the unsaturated alcohol (UOL) was the main product of the reaction, with higher UOL yields noted for ethanol than 2-propanol.

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Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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Theoretical Study on the Selective 1,2‐Reduction of α,β‐Unsaturated Ketones by Hydrogen Transfer Reaction on MgO(100)

2022

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Catalytic reduction of α,β‐unsaturated ketones with MgO has been found to improve selectivity to the desired unsaturated alcohol product. Using density functional calculations, we have studied the competitive hydrogenation of C=O and C=C bonds on Mg(100) employing two α,β‐unsaturated ketones: mesityl oxide (MO) and 2‐cyclohexenone (CH), with isopropanol (IPA) as hydrogen source. For both ketones, MgO promotes the formation of a six‐membered cyclic transition state for selective C=O reductions via a Meerwein‐Ponndorf‐Verley mechanism. Similar concerted mechanism is also possible for the C=C hydrogenation following an Eley‐Rideal mechanism, in which the IPA interacts directly with the adsorbed ketone. The activation barriers are smaller for C=O reduction because this bond is activated on MgO(100). The selective C=O reduction is more favorable for CH than for MO due to the tendency of CH to be perpendicularly oriented. The desorption energies of the unsaturated alcohol are lower than the subsequent C=C reductions.

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