578. Alicyclic compounds. Part III. Ultra-violet absorption, acidity, and ring fission of cyclohexane-1: 3-diones

Meek, Eric G.; Turnbull, J. H.; Wilson, Walter

doi:10.1039/jr9530002891

Cited by 10 publications

(3 citation statements)

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“…(Unfortunately, the experimental data for this point are for 5,5‐dimethyl‐1,3‐cyclohexanedione, but the effect of the remote methyls is likely to be small; the equilibrium constant in water is 19, favoring enol. In support of the assumption that the effect of a remote methyl is negligible, we point out that the pK a values for 1,3‐cyclohexandione and 5,5‐dimethyl‐1,3‐cyclohexandione are essentially identical …”

Section: Resultssupporting

confidence: 68%

Equilibrium constants for enolization in solution by computation alone

Guthrie

Povar

2013

J of Physical Organic Chem

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Equilibrium free energy changes for enolization in aqueous solution can be calculated with useful accuracy (rmse = 1.3 kcal/mol for 37 reactions). These calculations involve gas phase free energy changes calculated using the G3MP2B3 method and solvation energies calculated using the IPCM method corrected by a parameterization scheme which we have reported. For chloroacetones, we find a small preference for enolization to the halogenated side and a preference for forming an enol with Cl Z to the OH. This may be partly due to weak hydrogen bonding but must be partly due to a relief of crowding; 2-butanone also shows a preference for the Z-enol. There are serious disagreements between calculated and experimental values for some of the enolization equilibria of 1,3,5-cyclohexanetrione (phloroglucinol); we argue that the problems are with the experimental values. Reasonable values are obtained for the enolization of Meldrum's acid, diethyl malonate, and 1,3-cyclohexanedione. Computational equilibrium constants in aqueous solution are now viable as supplements to and checks on experiment.

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Section: Resultssupporting

confidence: 68%

Equilibrium constants for enolization in solution by computation alone

Guthrie

Povar

2013

J of Physical Organic Chem

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“…Jamieson et al (1970) stated that the resorcinol was formed from the undetected fragmentation of H 2 0 from DHPG (M + 128). In accordance with these results, synthesized product F (4 mg/L) and cyclohexane-l:3-dione (8.29 mg/L) (Meek et al 1953) exhibited similar uv spectral pH shifts, suggestive of a keto-en01 tautomerization. Product F and cyclohexane-l:3-dione shifted from 278 nm (pH 8.0) to 255 nm (pH 2.0), and from 280 nm (pH 8.0) to 255 nm (pH 2.0), respectively.…”

supporting

confidence: 81%

Abiotic conversion of dihydrophloroglucinol to resorcinol

Armstrong¹,

Patel²

1993

Can. J. Microbiol.

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Chemical conversion of a dihydrophloroglucinol preparation (a mixture of the tautomers 1,3,5-trihydroxy-1,3-cyclohexadiene, 1,3-dioxo-5-hydroxycyclohexane, and 3,5-dihydroxy-3-cyclohexene-1-one) to resorcinol occurred during a 24-h extraction of an acidic (pH 2.0) aqueous dihydrophloroglucinol preparation into ethyl acetate. This conversion did not occur at neutral pH, nor did phloroglucinol (1,3,5-trihydroxybenzene)-induced or succinate-induced Penicillium simplicissimum enzyme extracts convert the dihydrophloroglucinol preparation to resorcinol at pH values of 5.5–8.0. The chemical structure of the dihydrophloroglucinol preparation was determined by gas chromatography - mass spectrometry, high resolution 13C and 1H nuclear magnetic resonance, Fourier-transformed infrared spectrometry, and ultraviolet spectrophotometry. Resorcinol (1,2-dihydroxybenzene) was detected by gas chromatography - mass spectrometry or thin-layer chromatography and ultraviolet spectrophotometry. A chemical mechanism for the conversion of the dihydrophloroglucinol preparation to resorcinol is proposed.Key words: dihydrophloroglucinol, chemical conversion, resorcinol.

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“…Present address: The Upjohn Company, Kalamazoo, Michigan.3 It is interesting to compare the bathochromic shift caused by the -hydroxy substituent in a monocyclic a,|3-unsaturated ketone system. Thus, it is shown(8,9) that A8-2-hydroxy-3-methylcyclohexenone absorbs at Xmal 268.5 µ as compared to Xmax 235 ra;i for 2-3methylcyclohexenone(10).…”

mentioning

confidence: 97%

The Reaction of 2-Methyldihydroresorcinol With the Mannich Base From Methoxypropanone-2

Szmuszkovicz¹

1954

J. Org. Chem.

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578. Alicyclic compounds. Part III. Ultra-violet absorption, acidity, and ring fission of cyclohexane-1: 3-diones

Cited by 10 publications

References 0 publications

Equilibrium constants for enolization in solution by computation alone

Equilibrium constants for enolization in solution by computation alone

Abiotic conversion of dihydrophloroglucinol to resorcinol

The Reaction of 2-Methyldihydroresorcinol With the Mannich Base From Methoxypropanone-2

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