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81971-99-5 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 81971-99-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,9,7 and 1 respectively; the second part has 2 digits, 9 and 9 respectively.
Calculate Digit Verification of CAS Registry Number 81971-99:
165 % 10 = 5
So 81971-99-5 is a valid CAS Registry Number.

81971-99-5Relevant articles and documents

Protonation-deprotonation equilibria in tetrapyrroles Part 4: Mono- and diprotonations of deutero-, hemato-, meso-, and protoporphyrin IX dimethyl esters in methanolic hydrochloric acid

Hynninen, Paavo H.

, p. 385 - 395 (2015/05/20)

The N-protonations in the deutero, hemato, meso and protoporphyrin IX dimethyl esters (DME) were investigated by spectrophotometric titrations using HCl as the acid and methanol as the solvent. Two spectroscopically different protonated species were observed for each porphyrin DME in addition to the neutral form. These were assigned to the N-protonated monocation and dication. There were no difficulties encountered in observing the monocation formation in the HCl-MeOH system. Very sharp isosbestic points were characteristic of each protonation stage. The pK3 values for the porphyrins in the above order were 3.23, 4.70, 2.93 and 3.37; the pK4 values were 2.48, 2.62, 2.41 and 2.64, respectively. For all porphyrins studied, no further spectral changes were observed after the dication was completely formed. This was interpreted as indicating that the formation of more highly protonated species is not possible in fullydelocalized porphyrins possessing the 18 π-electron [18]diazaannulene delocalization pathway. When the titration was performed on the free dicarboxylic acid porphyrins, aggregation obscured the first protonation step and no clear monocation spectrum could be distinguished. However, also in that case the titration ended up to a UVvis spectrum typical of the dication and the effect of aggregation on the pK4 values was negligible. The UVvis spectrometric parameters are given for the neutral forms and for the protonated species of the porphyrin DMEs. The results are discussed in terms of the NH tautomerization connected to the π-electron delocalization pathway (aromaticity), which tends to hinder outofplane distortions in the porphyrin plane, and in terms of solvation and counterion stabilization of the protonated forms.

A facile synthesis of deuteroporphyrins derivatives under ultrasound irradiation

Hu, Bingcheng,Zhou, Weiyou,Tang, Ying,Huang, Chengmei,Liu, Zuliang

experimental part, p. 288 - 291 (2010/12/25)

A facile, efficient and general method for preparing deuteroporphyrin derivatives by using concentrated H2SO4 and alcohol under ultrasound irradiation has been developed. A series of new deuteroporphyrin derivatives bearing different propionic ester groups have been synthesized in good yields starting from readily accessible deuterohemin. The characterization of these compounds confirms the synthetic methodology. Compared with conventional methods, the main advantages of the present procedure are shorter reaction time and higher yields.

Synthesis and Reactivity of 131,132,171,172-Tetradehydrodeuteroporphin

Fuhrhop, Juergen-Hinrich,Lehmann, Thomas

, p. 1386 - 1389 (2007/10/02)

Die 13,17-Propionsaeure-methylester-Seitenketten des Deuteroporphyrin-dimethylesters (1a) wurden mit Phenylselenobromid zu 1b dehydriert.Die 12,18-Methylgruppen tauschten in Deuteriomethanol mit Natriummethoxid Wasserstoff gegen Deuterium aus.

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