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748159-01-5

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748159-01-5 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 748159-01-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 7,4,8,1,5 and 9 respectively; the second part has 2 digits, 0 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 748159-01:
(8*7)+(7*4)+(6*8)+(5*1)+(4*5)+(3*9)+(2*0)+(1*1)=185
185 % 10 = 5
So 748159-01-5 is a valid CAS Registry Number.

748159-01-5Downstream Products

748159-01-5Relevant articles and documents

On the tautomerism of pyrazolones: The geminal 2J[pyrazole C-4,H-3(5)] spin coupling constant as a diagnostic tool

Holzer, Wolfgang,Kautsch, Constanze,Laggner, Christian,Claramunt, Rosa M.,Pérez-Torralba, Marta,Alkorta, Ibon,Elguero, José

, p. 6791 - 6805 (2007/10/03)

The tautomerism of pyrazolones unsubstituted at position 3(5) has been investigated by 13C- and 1H NMR spectroscopic methods. Apart from chemical shift considerations and NOE effects the magnitude of the geminal 2J[pyrazole C-4,H3(5)] spin coupling constant permits the unambiguous differentiation between 1H-pyrazol-5-ol (OH) and 1,2-dihydro-3H-pyrazol-3-one (NH) forms. Whereas 1H-pyrazol-5-ols and 2,4-dihydro-3H-pyrazol-3-ones (CH-form) exhibit 2J values of approximately 9-11 Hz, in 1,2-dihydro-3H-pyrazol-3-ones this coupling constant is considerably reduced to 4-5 Hz. This can be mainly attributed to the removal of the lone-pair at pyrazole N-1 in the latter due to protonation or alkylation. According to the data obtained, 2-substituted 4-acyl-1,2-dihydro-3H-pyrazol-3- ones exist predominantly as pyrazol-5-ols in CDCl3 or benzene-d 6 solution, whereas in DMSO-d6 also minor amounts of NH tautomer may contribute to the tautomeric composition. 2,4-Dihydro-2-phenyl-3H- pyrazol-3-one (1-phenyl-2-pyrazolin-5-one) exists in benzene-d6 solely in the CH-form, in CDCl3 as a mixture of CH and OH-form, whereas in DMSO-d6 a fast equilibrium between OH and NH isomer (with the former far predominating) is probable. For 11 compounds, including neutral and protonated molecules, we have calculated at the B3LYP/6-311++G** level, the 2J(1H,13C) coupling constants which are in good agreement with those measured experimentally.

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