Isotope Effects in Deuterium Oxide Solution. I. Acid-Base Equilibria

Bunton, C. A.; Shiner, V. J.

doi:10.1021/ja01462a008

Cited by 91 publications

(42 citation statements)

References 1 publication

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“…We find that the addition of an A4ln T term in eq (11) leads, in some cases, to almost the same values of tmin and pKmin as those recorded in table 8. Thus, for acetic acid in deuterium oxide, tmin = .~2.6 °C, pKmin = 5.309; for deuterioacetic acid in deuterium oxide, trnin = 32.3, pKmin = 5.323; for the second step in the dissociation of phosphoric acid in deuterium oxide, tmin = 49.1 °C, pKmin = 7.743.…”

Section: Influence Of Temperature On the Isotope Effectsupporting

confidence: 71%

“…From this study and the work of LaMer and hi s colleagues [3,4,5] and of Martin and Butler [6], it appears that the differenc e in pK value, 6.pK= pK (in D2 0)-pK (in H20), increases approximately linearly with an increase in pK (in H20). Thi s r elation has been ascribed [7] to a difference in zero-point energy between the isotopes in the acid molec ules or perhaps [8] to a differe nce in zero-point e nergy between th e hydrogen-bonded molecules and th e solvent. Th us, 6.pK = 0.43 for c hloroac etic acid, 0.50 for benzoic acid [5], and 0.56 for p-nitrophenol [6].…”

Section: Introductionmentioning

confidence: 99%

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Deuterium isotope effect on the dissociation of weak acids in water and deuterium oxide

Robinson¹,

Paabo²,

Bates³

1969

J. RES. NATL. BUR. STAN. SECT. A.

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Th e di ssoc iation co ns tants of o-n itroan ilinium ion, m-nitroan ili nium ion , a nd 4-c hl oro-2,6-d init ropheno l in d e ute rium ox ide at 25°C have bee n det e rmin e d b y a spectro photom etric meth od , a nd a n e mf m e thod has bee n used to obtain (pK, + pK2 )/2 for citri c acid in deuterium ox id e . In addit ion , d a ta fur th e di ssoc iation co ns tant s of other wea k ac id s in ordinary and heavy wa te r have bee n c riti c ally exa mine d with a vi e w to c larifyin g th e relatio ns hip be twee n th e deute rium isotope e ffec t and th e intrins ic s tre ngth o f th e acid. Th e differe nce t:J.pK b et wee n th e pK va lu e in de ute rium ox id e and that in wat e r vari es lin early with pK above pK = 7_ Two s tron ge r in o rganic ac id s (su lfuri c and phosphoric) a lso a ppea r to lie on an e xte ns ion of thi s sa me lin e. On th e co ntra ry, a co ns id e rabl e group of o rga ni c ac id s with pK less than 7 have va lu es of t:J.pK th a t are more or less co ns tant nea r t:J.pK = 0. 55. It appears, th e re fo re, that th e isotope e ffec t is more co mpl e x th a n has he re tofore been ass um ed. Ke y word s: Ac idi c di ssoc iat ion; ac idity ; deut e rium isotope e ffec t; dis sociation co nstants; he avy wat er ; isotope e ffec t ; pK value s .

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Section: Influence Of Temperature On the Isotope Effectsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Deuterium isotope effect on the dissociation of weak acids in water and deuterium oxide

Robinson¹,

Paabo²,

Bates³

1969

J. RES. NATL. BUR. STAN. SECT. A.

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“…Tile ratio of the rates in 1320 and D 2 0 is close to unity (7) for the hyclration of 2-metlz) 1-2-butenc and 1-metll) 1-1-cyclopentcne, ~v l~e r c a s it is 2.2 (11) for the adclition of concentratecl sulphuric acid t o ethylene ancl 2.8 for hydration of propylene (12) in 90% aqueous fornlic acid. Willi (13) has argued t h a t an isotope effect of near unity is collsistcllt with a 4-centered trallsitioll state whereas Bunton and Shiner (14) have suggested t h a t a n isotope effect of near unity favors either of the following transition states Can. J. Chem.…”

mentioning

confidence: 99%

Pressure Effect and Mechanism in the Acid-Catalyzed Hydration of Propylene and Isobutylene

Baliga¹,

Whalley²

1964

Can. J. Chem.

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The effect of pressure LIP to 3 lcbar on the rate of the acicl-catalyzecl hydration of propylene and isobutylene has been measured. 'The volumes of activation are: for propylene a t 100' C -9.6 A -1.0 cm3 mole-', and for isobutylene a t 35" C -11.5 A -1.0 cm3 mole-'. The effect of temperature in the range 90-120" C 011 the rate of hydration of propylene a t 100 bar was measured. At 100" C the Arrhenius energy is 27

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“…Thus the primary and secondary esters give s.i.e. ratios in the range 3.4-3.8, which have predicted to be characteristic of spontaneous BAc2 processes (32). On the other hand, the tertiary ester gives a s.i.e.…”

Section: Solvent Isotope Effectmentioning

confidence: 93%

Studies in solvolysis. Part I. The neutral hydrolysis of some alkyl trifluoroacetates in water and deuterium oxide

Winter¹,

Scott²

1968

Can. J. Chem.

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The temperature dependence of the rates of neutral hydrolysis of a series of alkyl trifluoroacetates (CF3COOR; R = methyl, ethyl, s-propyl, t-butyl) has been determined in both light and heavy water. From these studies the thermodynamic parameters (AH*, AS*) which characterize the activation process have been calculated. Sufficient rate data have been obtained in the case of the ethyl ester to calculate the heat capacity of activation (AC,*) for the hydrolysis of this compound in light water. Both the entropies and enthalpies of activation as well as the solvent isotope effects are consistent with the proposal that the primary and secondary esters react by an acyl-oxygen B,,2 mechanism, in contrast to the tertiary ester, which appears to react either by a carbonium ion (SN1) process or by a route which combines both the B,,2 and SN1 paths.

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Isotope Effects in Deuterium Oxide Solution. I. Acid-Base Equilibria

Cited by 91 publications

References 1 publication

Deuterium isotope effect on the dissociation of weak acids in water and deuterium oxide

Deuterium isotope effect on the dissociation of weak acids in water and deuterium oxide

Pressure Effect and Mechanism in the Acid-Catalyzed Hydration of Propylene and Isobutylene

Studies in solvolysis. Part I. The neutral hydrolysis of some alkyl trifluoroacetates in water and deuterium oxide

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