Pyrolysis Studies. XV. Thermal Retrograde Aldol Condensation of β-Hydroxy Ketones<sup>1a</sup>

Smith, Grant Gill; Yates, Brian L.

doi:10.1021/jo01017a515

Cited by 25 publications

(11 citation statements)

References 1 publication

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“…β‐Hydroxy ketones decompose thermally to give mixtures of aldehydes and/or ketones in a reaction, which is the reverse of the aldol condensation (Fig. ).…”

Section: Introductionsupporting

confidence: 81%

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

Henao

Murillo²,

Ruíz

et al. 2012

J of Physical Organic Chem

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Theoretical calculations at the M05‐2X/6‐31+G(d) level of theory have been carried out in order to explore the nature of the mechanism of the thermal decomposition reactions of the β‐hydroxy ketones, 4‐hydroxy‐2‐butanone, 4‐hydroxy‐2‐pentanone, and 4‐hydroxy‐2‐methyl‐2‐pentanone in gas phase and in m‐xylene solution. The mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state. A reasonable agreement between experimental and calculated activation parameters and rate constants has been obtained, the tertiary : secondary : primary alcohol rate constant ratio being calculated, at T = 503.15 K, as 5.9:4.7:1.0 in m‐xylene solution and 44.1:5.0:1.0 in the gas phase, compared with the experimental values, 3.7:1.3:1.0 and 13.5:3.2:1.0, respectively. The progress of the thermal decomposition reactions of β‐hydroxy ketones has been followed by means of the Wiberg bond indices. The lengthening of the O1–C2 bond with the initial migration of the H6 atom from O5 to O1 can be seen as the driving force for the studied reactions. Calculated synchronicity values indicate that the mechanisms correspond to concerted and highly synchronous processes. The transition states are “advanced”, nearer to the products than to the reactants. Copyright © 2012 John Wiley & Sons, Ltd.

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“…β‐Hydroxy ketones decompose thermally to give mixtures of aldehydes and/or ketones in a reaction, which is the reverse of the aldol condensation (Fig. ).…”

Section: Introductionsupporting

confidence: 81%

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

Henao

Murillo²,

Ruíz

et al. 2012

J of Physical Organic Chem

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“…4) with hydrogen bonds between Cαand Cγ-hydroxyl groups. Cyclic transition state mechanism is proposed for pyrolysis of β-hydroxy ketones, 22,23 β-hydroxy olefins 24 and β,γ-unsaturated acids. 25,26 For example, thermal retrograde aldol condensation of some β-hydroxy ketone is reported to proceed much faster in the structure which can form a cyclic transition state than other similar β-hydroxy ketones.…”

Section: Resultsmentioning

confidence: 99%

Effects of side-chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic lignin model dimer

2007

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Effects of side-chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic model dimers were studied with various deoxygenated dimers under the pyrolysis conditions of N2 / 400 o C / 1min. Although phenolic dimer with hydroxyl groups at Cα-and Cγ-positions was much more reactive than the corresponding non-phenolic type, deoxygenation at the Cγ-position substantially reduced the reactivity up to the level of the non-phenolic type. These results are discussed with the cleavage mechanism via quinone methide intermediate formation, which is activated through intramolecular hydrogen bonds between Cα-and Cγ-hydroxyl groups.

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“…The mechanism of thermal decomposition of β‐hydroxy ketones has been studied in many previous works both in the gas phase and in solution 1–3. These decompose thermally to give a mixture of aldehydes and/or ketones in a reaction, which is the reverse of the aldol condensation 1. 4‐Hydroxy‐4‐methyl‐2‐pentanone was determined in the true homogeneous gas‐phase state by Smith and Yates 1.…”

Section: Introductionmentioning

confidence: 99%

“…These decompose thermally to give a mixture of aldehydes and/or ketones in a reaction, which is the reverse of the aldol condensation 1. 4‐Hydroxy‐4‐methyl‐2‐pentanone was determined in the true homogeneous gas‐phase state by Smith and Yates 1. Additional kinetic studies of two other β‐hydroxy ketones, i.e., 4‐hydroxy‐3‐methyl‐2‐pentanone and 4‐hydroxy‐2‐pentanone, were studied in a xylene solution to examine the influence of the substituted methyl group on the mechanism and velocity 2.…”

Section: Introductionmentioning

confidence: 99%

Thermal decomposition of 4‐hydroxy‐2‐butanone in m‐xylene solution: Experimental and computational study

Murillo

Henao

Vélez

et al. 2012

Int J of Chemical Kinetics

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The mechanism of thermal decomposition of 4-hydroxy-2-butanone in m-xylene solution was studied experimentally and theoretically at the M05-2X/6-31G(d , p) level of theory. It follows first-order kinetics and appears to be homogeneous and unimolecular. The proposed mechanism is via a six-membered cyclic transition state to give a mixture of formaldehyde and acetone. Rate constant values were experimentally determined at three temperatures: 483.15, 493.15, and 503.15 K. Calculated rate constants are of the same order of magnitude than the experimental ones. Calculated Gibbs energies of activation agree very well with the experimental values. Computationally, the progress of the reactions was followed by means of the Wiberg bond index. The results indicate that the transition state has an intermediate character between reactants and products, and the calculated synchronicity shows that the reaction is slightly asynchronous. The bond-breaking processes are more advanced than the bond-forming ones, indicating a bond deficiency in the transition state.

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Pyrolysis Studies. XV. Thermal Retrograde Aldol Condensation of β-Hydroxy Ketones^1a

Cited by 25 publications

References 1 publication

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

Effects of side-chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic lignin model dimer

Thermal decomposition of 4‐hydroxy‐2‐butanone in m‐xylene solution: Experimental and computational study

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Pyrolysis Studies. XV. Thermal Retrograde Aldol Condensation of β-Hydroxy Ketones1a

Cited by 25 publications

References 1 publication

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

A computational study of the thermolysis of β‐hydroxy ketones in gas phase and in m‐xylene solution

Effects of side-chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic lignin model dimer

Thermal decomposition of 4‐hydroxy‐2‐butanone in m‐xylene solution: Experimental and computational study

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Pyrolysis Studies. XV. Thermal Retrograde Aldol Condensation of β-Hydroxy Ketones^1a