A kinetic study of the mechanism of esterification of 1-arylethanols in trifluoroacetic acid

Gillen, Ciaran J.; Knipe, A. C.; Watts, William E.

doi:10.1016/s0040-4039(01)90166-2

Cited by 7 publications

(18 citation statements)

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“…Both trifluoro acetyl groups appear in 13 Figure 6b. 1 H and 13 C-NMR spectra in CDCl3 of the compound 8a and that of the esterified compound 8c, formed in 24 h after addition of TFA Corey lactone 9a, with an oxabicyclo[3.3.0]octane fragment, was esterified to both primary and secondary alcohols group, without the observation of the selective trifluoro acetylation of the primary alcohol before begins the trifluoroacetylation of the secondary alcohols (Experimental,9). In 13 C-NMR, both trifluoro acetyl groups appear in NMR spectra, at 157.41 and 114.26 ppm for COCF3 and COCF3 of the primary alcohol ester, respectively 157.10 and 114.61 ppm for COCF3 and COCF3 for the secondary alcohol ester.…”

Section: Resultsmentioning

confidence: 99%

“…It is worth mentioned that the trifluoroacetylation proceeded faster than that in DMSO-d6, where also an additional amount of TFA did not lead to completion of the esterification reaction. The results are to be taken into consideration when TFA is added in NMR tube, because not only the shifting of the couplings of the deuterable protons could help us to simplify the NMR spectrum, but also trifluoro acetylation could help us to more precisely attribute the signals in 1 H-and 13 C-NMR spectra to the protons and carbon atoms in the molecule.…”

Section: Resultsmentioning

confidence: 99%

“…In conclusion, TFA added in NMR tube, not only shifts the deuterable protons and simplify the NMR spectrum, but by trifluoroacetylation of the alcohol groups cloud make easier and more precisely attribution of the signals in 1 H-and 13 C-NMR spectra to the protons and carbon atoms in the molecule.…”

Section: Discussionmentioning

confidence: 95%

“…14.NMR spectra of the compound 12a and of the bis-trifluoroacetylated compound 12c. The un-symmetric triol 12 was esterified with trifluoroacetic anhydride in TFA (in NMR tube) and the complete esterification proceeded in 4 h. The signals of the bis-triflouroacetylated compound 12c are described below: 1 [20]).…”

Section: Methodsmentioning

confidence: 99%

“…A routine NMR characterization of a compound with a primary alcohol group needed to distinguish between two protons and after adding trifluoroacetic acid (TFA) in the tube we observed the appearance of signals which proved to be those of the trifluoro acetylated compound formed quantitatively after a day. Browsing the literature, we found that alcohols are even quantitative esterified with TFA [1,2]. For example, synthesis of ethyl trifluoroacetate from ethyl alcohol and TFA is also mentioned in patents [3][4][5][6] and journals [7].…”

Section: Introductionmentioning

confidence: 99%

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Trifluoroacetylation of Alcohols During NMR Study of Compounds with Bicyclo[2.2.1]heptane, Oxabicyclo[3.3.0]octane and Bicyclo[3.3.0]octane Skeleton

Tănase¹,

Hanganu²,

Drăghici³

2021

Rev. Chim.

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TFA was added to a solution of a bicyclo[2.2.1]heptane azide-alcohol in CDCl3 to correctly characterize the compound, but during 24 h gave the trifluoro acetylated compound in quantitative yield. NMR spectra of the esterified compound helped us also to correctly attribute the NMR signals to the protons, and also confirmed the identification of the carbon atoms. The study was extended to other 14 compounds containing a primary alcohol group alone or with an ethylene ketal, a δ- or -lactone group, a primary and a secondary group, two primary and an alkene group and two primary and a secondary alcohol groups on scaffolds containing bicyclo[2.2.1]heptane, oxabicyclo[3.3.0]octane, bicyclo [2.2.1]heptane constrained with a cyclopropane ring and bicyclo[3.3.0]octane fragments. The esterification of all compounds was also quantitative in 24 to 72 h; this helped us to correct attribute the NMR signals to the protons and carbon atoms of the un-esterified compounds by comparison with those of the trifluoro acetylated compounds. A graphical presentation of 1H- and 13C-NMR spectra of a few un-esterified and esterified compounds are presented in the paper.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Trifluoroacetylation of Alcohols During NMR Study of Compounds with Bicyclo[2.2.1]heptane, Oxabicyclo[3.3.0]octane and Bicyclo[3.3.0]octane Skeleton

Tănase¹,

Hanganu²,

Drăghici³

2021

Rev. Chim.

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Ab initio and density functional theory studies of the catalytic mechanism for ester hydrolysis in serine hydrolases

Brinck

Hult

1998

Int. J. Quant. Chem.

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ABSTRACT:We present results from ab initio and density functional theory studies of the mechanism for serine hydrolase catalyzed ester hydrolysis. A model system containing both the catalytic triad and the oxyanion hole was studied. The catalytic triad was represented by formate anion, imidazole, and methanol. The oxyanion hole was represented by two water molecules. Methyl formate was used as the substrate. In the acylation step, our computations show that the cooperation of the Asp group and oxyanion hydrogen bonds is capable of lowering the activation barrier by about 15 kcalrmol. The transition state leading to the first tetrahedral intermediate in the acylation Ž . step is rate limiting with an activation barrier ⌬ E of 13.4 kcalrmol. The activation 0 barrier in the deacylation step is smaller. The double-proton-transfer mechanism is energetically unfavorable by about 2 kcalrmol. The bonds between the Asp group and the His group, and the hydrogen bonds in the oxyanion hole, increase in strength going from the Michaelis complex toward the transition state and the tetrahedral intermediate. In the acylation step, the tetrahedral intermediate is a very shallow minimum on the energy surface and is not viable when molecular vibrations are included.

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The Effect of Trifluoroacetic Acid on Molecular Weight Determination of Polyesters: An in Situ NMR Investigation

Wan

Huan

et al. 2021

Chin J Polym Sci

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A kinetic study of the mechanism of esterification of 1-arylethanols in trifluoroacetic acid

Cited by 7 publications

References 1 publication

Trifluoroacetylation of Alcohols During NMR Study of Compounds with Bicyclo[2.2.1]heptane, Oxabicyclo[3.3.0]octane and Bicyclo[3.3.0]octane Skeleton

Trifluoroacetylation of Alcohols During NMR Study of Compounds with Bicyclo[2.2.1]heptane, Oxabicyclo[3.3.0]octane and Bicyclo[3.3.0]octane Skeleton

Ab initio and density functional theory studies of the catalytic mechanism for ester hydrolysis in serine hydrolases

The Effect of Trifluoroacetic Acid on Molecular Weight Determination of Polyesters: An in Situ NMR Investigation

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