A Study of the Esterification of Benzoic Acid with Methyl Alcohol Using Isotopic Oxygen

Roberts, Irving; Urey, Harold C.

doi:10.1021/ja01277a028

Cited by 52 publications

(11 citation statements)

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“…Obviously, the mechanism is consistent with Urey and Robert's experimental result. 2 This mechanism is also in agreement with the results of ester carbonyl-O 18 exchange experiments. [13][14][15][16] Conclusion DFT calculations and ESI-MS data have proved that the acidcatalyzed carboxylic acid esterification and ester hydrolysis mechanism proposed by Watson 5,6 80 years ago is incorrect.…”

Section: Proposed Acid-catalyzed Carboxylic Acid Esterification and E...supporting

confidence: 87%

“…However, the reaction can usually reach equilibrium quickly with a small amount of concentrated sulfuric acid or hydrogen chloride as catalyst. During the 1920's and 1930's, chemists [2][3][4][5][6][7][8] conducted a large number of experimental and theoretical studies with regards to the acid-catalyzed carboxylic acid esterification mechanism. At that time, an important question regarding the mechanism was the origin of the alkyl-oxygen in the formation of the ester.…”

Section: Introductionmentioning

confidence: 99%

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Acid-catalyzed carboxylic acid esterification and ester hydrolysis mechanism: acylium ion as a sharing active intermediate via a spontaneous trimolecular reaction based on density functional theory calculation and supported by electrospray ionization-mass spectrometry

Shi

Wang

Hua

2015

Phys. Chem. Chem. Phys.

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By DFT calculation, we found that acid-catalyzed carboxylic acid esterification and ester hydrolysis are brief two-step reactions. First, the carboxylic acid hydroxyl-oxygen or ester alkyl-oxygen is protonated, which generates a highly active acylium ion. The protonation requires an activation energy (Ea) of 4-10 kcal mol(-1), and is the rate-controlling step of the esterification or hydrolysis. Sequentially, the acylium ion spontaneously reacts with two alcohol or two water molecules to form a neutral product molecule; this is a trimolecular reaction. The acylium ion is the highly active intermediate shared by esterification and hydrolysis. ESI-MS data for several typical carboxylic acids confirmed that their acylium ions are easily generated. For 2,4,6-trialkylbenzoic acid and its ester, the two unsubstituted carbons in the benzene ring are very easily protonated, and we have thus revealed the root of the success of Newman's method. Based on these results, the popular esterification and hydrolysis mechanism in organic chemistry textbooks is incorrect.

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Section: Proposed Acid-catalyzed Carboxylic Acid Esterification and E...supporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Acid-catalyzed carboxylic acid esterification and ester hydrolysis mechanism: acylium ion as a sharing active intermediate via a spontaneous trimolecular reaction based on density functional theory calculation and supported by electrospray ionization-mass spectrometry

Shi

Wang

Hua

2015

Phys. Chem. Chem. Phys.

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“…This is analogous to the Fischer− Speier mechanism described for esterification reactions involving carboxylic acids and alcohols. 42 Urey and Roberts 43 demonstrated that reacting 18 O-labeled methyl alcohol with benzoic acid results in a 18 O-labeled methyl benzoate ester. Thus, the condensed water molecule produced in this reaction contained the oxygen from benzoic acid.…”

Section: ■ Computational Methodsmentioning

confidence: 99%

Mechanism and Reaction Energy Landscape for Apiose Cross-Linking by Boric Acid in Rhamnogalacturonan II

et al. 2020

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Rhamnogalacturonan II (RG-II)the most complex polysaccharide known in natureexists as a borate cross-linked dimer in the plant primary cell wall. Boric acid facilitates the formation of this cross-link on the apiosyl residues of RG-II's side chain A. Here, we detail the reaction mechanism for the cross-linking process with ab initio calculations coupled with transition state theory. We determine the formation of the first ester linkage to be the rate-limiting step of the mechanism. Our findings demonstrate that the regio-and stereospecific nature of subsequent steps in the reaction itinerary presents four distinct energetically plausible reaction pathways. This has significant implications for the overall structure of the cross-linked RG-II dimer assembly. Our transition state and reaction path analyses reveal key geometric insights that corroborate previous experimental hypotheses on borate ester formation reactions.

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“…These pioneer workers showed that in the alkaline hydrolysis of amyl acetate, substitution takes place at the carbonyl rather than alkyl carbon. Roberts & Urey (106) showed that in the esterification of benzoic acid by CHaOH in acid, again the alkyl oxygen bond is preserved. Datta, Day & Ingold (42) showed that the methyl-oxygen bond remains intact in the alkaline hydrolysis of methyl succinate.…”

Section: Miscellaneous Exchange Reactionsmentioning

confidence: 99%

Applications of Oxygen Isotopes in Chemical Studies

Taube¹

1956

Annu. Rev. Nucl. Sci.

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The choice of the general subject of this article requires no apology, but the choice of the specific material to fit to the space allotted does. The limita tions and research interests of the reviewer were a governing factor in mak ing the selection, but also the consideration entered that the effects of the major omissions are tempered by other recent reviews in which much of the material omitted is discussed. Thus the important work in geochemistry involving oxygen isotopes is discussed in excellent reviews by Dole (I), and more recently by Craig & Boata (2). The work on heterogenous systems is discussed more completely in the article by Dole. It is hoped in this connec tion that a general article on the application of isotopes in the study of heterogeneous catalysis, induding work with oxygen isotopes, will be forth coming. In the subjects chosen for review, an effort has been made to be com plete ; and earlier literature as well as the more recent has been referred to. When work which is within the scope of the subject matter is not cited, it is because of oversight or because the work is dealt with in a more general article by the same author.The present article stresses the application of oxygen isotopes to the study of chemical phenomena in homogeneous solution. Much of the work exploiting oxygen isotope effects has been done for such systems. For reac tions of oxygen-containing substances in an oxide-labile solvent such as water, isotope studies can answer important questions which no other method can answer as directly; and they have been of great help in defining the nature of the solvent and of the substances dissolved in it, and in exposing the mechanisms of reactions in solution. TECHNIQUESIn the work reviewed, mainly the oxygen isotopes of mass 18 and 16 come into question. The mass spectrometric method of measuring isotope ratios has almost completely supplanted that depending on the determination of density differences in water. With care, commercial instruments can measure differences to a precision of 1 part in 1000 in O2 or CO2 of normal oxygen isotopic composition. With specially designed instruments (3), a precision of one part in approximately 10,000 on CO2 can be attained.When the oxygen is available as water, an accurate method (4) of isotopic assay is equilibration of CO2 with the H20, followed by measurement of the isotopic ratio in the CO2• Dostrovsky & Klein (5) have described the high temperature equilibration of CO2 and H20, and have derived an equation 1 The survey of literature pertaining to this review was completed in January, 1956.

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A Study of the Esterification of Benzoic Acid with Methyl Alcohol Using Isotopic Oxygen

Cited by 52 publications

References 0 publications

Acid-catalyzed carboxylic acid esterification and ester hydrolysis mechanism: acylium ion as a sharing active intermediate via a spontaneous trimolecular reaction based on density functional theory calculation and supported by electrospray ionization-mass spectrometry

Acid-catalyzed carboxylic acid esterification and ester hydrolysis mechanism: acylium ion as a sharing active intermediate via a spontaneous trimolecular reaction based on density functional theory calculation and supported by electrospray ionization-mass spectrometry

Mechanism and Reaction Energy Landscape for Apiose Cross-Linking by Boric Acid in Rhamnogalacturonan II

Applications of Oxygen Isotopes in Chemical Studies

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