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CAS NO. 119141-89-8

(RS)-5-methoxy-2-((4-methoxy-3,5-dimethylpyridin-2-yl) methylsulfinyl)-1H-benzo[d]imidazole

CAS No.: 119141-89-8
  • LOSEC;
  • ANTRA;
  • H 168/68;
Formula: C17H19N3O3S
Exact Mass: 345.11500

Ome is a chemical substance (C17H19N3O3S), its molecular weight is 345.42g/mol, the color is white, has weak alkaline properties, melts at 156oC

ome 1h nmr






OMEPRAZOLE NMR spectra analysis, Chemical CAS NO. 119141-89-8 NMR spectral analysis, OMEPRAZOLE H-NMR spectrum


OMEPRAZOLE NMR spectra analysis, Chemical CAS NO. 119141-89-8 NMR spectral analysis, OMEPRAZOLE C-NMR spectrum


COSY NMR prediction (7)


HMBC, HSQC NMR prediction (1)



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ARKIVOC 2006 (v) 5-11

The structure of Omeprazole in the solid state: a 13C and 15N NMR/CPMAS study

Rosa M. Claramunt,a Concepción López,a and José Elguerob *

a Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED, Senda del Rey 9, E-28040 Madrid, Spain

b Instituto de Química Médica, CSIC, Juan de la Cierva, 3. E-28006 Madrid, Spain



The 13C and 15N CPMAS spectra of a solid sample of Omeprazole have been recorded and all the signals assigned. The sample consists uniquely of the 6-methoxy tautomer. For analytical purposes, the signals of the other tautomer, the 5-methoxy one, were estimated from the data in solution (Magn. Reson. Chem. 2004, 42, 712).

Keywords: Omeprazole, NMR, 13C, 15N, CPMAS, tautomerism, benzimidazole

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Omeprazole, 5(6)-methoxy-2-{(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl}-1H-benz – imidazole [1(2)], is an important ulcer drug,1 that has been classified amongst the blockbuster drugs.2 This compound presents two sources of structural differentiation. First, Omeprazole is chiral (a vs. b) 3 since it has a stereogenic center on the sulfur atom but the commercial form has been sold, until recently, as a racemate. In 2001, Esomeprazole magnesium, the S enantiomer was approved.4 The second source of diversity is that these compounds present tautomerism (1 vs. 2). We have already devoted a paper to the tautomerism of Omeprazole in solution using 1 H and 13C NMR spectroscopy.5 In this paper a complete assignment of the signals was carried out and the tautomeric equilibrium constant, KT = [2]/[1], was determined in THF at 195 K, to be 0.59 in favor of the 6-methoxy tautomer 2.

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1. Carlsson, E.; Lindberg, P.; von Unge, S. Chem. Brit. 2002, 38, 42 and references therein.

2. Berkowitz, B. A.; Sachs, G. Mol. Interventions 2002, 2, 6.

3. von Unge, S.; Langer, V.; Sjölin, L. Tetrahedron: Asymmetry 1997, 8, 1967.

4. Olbe, L.; Carlsson, E.; Lindberg, P. Nature Reviews Drug Discovery 2003, 2, 132.

5. Claramunt, R. M.; López, C.; Alkorta, I.; Elguero, J.; Yang, R.; Schulman, S. Magn. Reson. Chem. 2004, 42, 712.

6. Elguero, J.; Katritzky, A. R.; Denisko, O. Adv. Heterocycl. Chem. 2000, 76. 1.

7. Allen, F. H. Acta Crystallogr. Sect. B 2002, 58, 380.

8. Braga, S. S.; Ribeiro-Claro, P.; Pillinger, M.; Gonçalves, I. S.; Fernandes, A. C.; Pereira, F.; Romåo, C. C.; Correia, P. B.; Teixeira-Dias, J. J. C. J. Incl. Phenom. Macro. Chem. 2003, 47, 47.

9. Berger, S.; Braun, S. 200 and More NMR Experiments. Wiley-VCH, Weinheim, 2004.

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UV Study: The Ultraviolet spectrum was recorded from 200 nm to 400 nm, with API concentration of 0.0015% in methanol. The spectrum showed two λmax at 207 and 301 nm. As seen below.

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FTIR Study The FTIR of spectrum of Omeprazole was recorded by preparation of pellet with KBr.

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13 C NMR


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The mass spectrum of Omeprazole was recorded on 4000-Q trap LCMSMS system. The sample is introduced into the system through HPLC by bypassing the column. The ESI +ve ionization spectrum of Omeprazole displayed a protonated molecular ion at m/z= 346 which corresponds to the molecular formula C17H17N3O3S. The fragmentation pattern was observed with product ion scan.

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Title: Omeprazole
CAS Registry Number: 73590-58-6
CAS Name: 5-Methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole
Manufacturers’ Codes: H-168/68
Trademarks: Gastrogard (Merial); Losec (AstraZeneca); Mopral (AstraZeneca); OmeLich (Winthrop); Omelind (Lindopharm); Omepral (AstraZeneca); Omeprazen (Malesci); Osiren (Probiomed); Parizac (Lacer); Pepticum (Grñenthal); Prilosec (AstraZeneca); Zegerid (Santarus); Zoltum (AstraZeneca)
Molecular Formula: C17H19N3O3S
Molecular Weight: 345.42
Percent Composition: C 59.11%, H 5.54%, N 12.16%, O 13.90%, S 9.28%
Literature References: Gastric proton-pump inhibitor. Prepn: U. K. Junggren, S. E. Sjostrand, EP 5129; eidem, US 4255431(1979, 1981 both to AB Hässle). Resolution and activity of enantiomers: P. Erlandsson et al., J. Chromatogr. 532, 305 (1990). Manuf process for optically pure salts: S. Von Unge, US 5693818 (1997 to Astra). Pharmacology: P. Muller et al., Arzneim.-Forsch. 33, 1685 (1983). Mechanism of action study: B. Wallmark et al., Biochim. Biophys. Acta 778, 549 (1984). LC determn in plasma and urine: P. Lagerstrom, B. Persson, J. Chromatogr. 309, 347 (1984). Survey of preclinical data: Scand. J. Gastroenterol. 20, Suppl 108, 1-120 (1985). Toxicological studies: L. Ekman et al., ibid. 53. Clinical trial in Zollinger-Ellison syndrome: C. B. H. W. Lamers et al., N. Engl. J. Med. 310, 758 (1984); in duodenal ulcer: K. Lauritsen et al., ibid. 312, 958 (1985). Veterinary trial in race horses: M. J. Murray et al., Equine Vet. J. 29, 425 (1997). Review of pharmacology and clinical efficacy: H. D. Langtry, M. I. Wilde, Drugs 56, 447-486 (1998).
Properties: Crystals from acetonitrile, mp 156°. Freely sol in ethanol, methanol; slightly sol in acetone, isopropanol; very slightly sol in water. LD50 in mice, rats (g/kg): 0.08, >0.05 i.v.; >4, >4 orally (Ekman).
Melting point: mp 156°
Toxicity data: LD50 in mice, rats (g/kg): 0.08, >0.05 i.v.; >4, >4 orally (Ekman)
Derivative Type: Magnesium salt
CAS Registry Number: 95382-33-5
Trademarks: Antra (AstraZeneca); Gastracid (AWD); Gastroloc (AstraZeneca); Omebeta (Betapharm); Omep (Hexal); Ome-Puren (Alpharma)
Molecular Formula: C34H36MgN6O6S2
Molecular Weight: 713.12
Percent Composition: C 57.26%, H 5.09%, Mg 3.41%, N 11.78%, O 13.46%, S 8.99%
Derivative Type: S-Form
CAS Registry Number: 119141-88-7
Additional Names: Esomeprazole; perprazole
Manufacturers’ Codes: H-199/18
Literature References: LC-MS determn in plasma: H. Stenhoff et al., J. Chromatogr. B 734, 191 (1999).
Properties: Colorless syrup. [a]D20 -155° (c = 0.5 in chloroform).
Optical Rotation: [a]D20 -155° (c = 0.5 in chloroform)
Derivative Type: S-Form magnesium salt
CAS Registry Number: 161973-10-0
CAS Name: (T-4)-Bis[5-methoxy-2-[(S)-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazolato]magnesium
Additional Names: esomeprazole magnesium
Trademarks: Nexium (AstraZeneca)
Literature References: Review of clinical experience in acid disorders: D. A. Johnson, Expert Opin. Pharmacother. 4, 253-264 (2003).
Properties: White powder. [a]D20 -128.2° (c = 1 in methanol).
Optical Rotation: [a]D20 -128.2° (c = 1 in methanol)
Therap-Cat: Antiulcerative; in treatment of Zollinger-Ellison syndrome.
Therap-Cat-Vet: Antiulcerative.
Keywords: Antiulcerative; Gastric Proton Pump Inhibitor.
P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.
P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.
P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.


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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK LIFE SCIENCES LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 30 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri, Dr T.V. Radhakrishnan and Dr B. K. Kulkarni, etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him Open superstar worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international, etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 30 PLUS year tenure till date June 2021, Around 35 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 90 Lakh plus views on dozen plus blogs, 233 countries, 7 continents, He makes himself available to all, contact him on +91 9323115463, email, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 33 lakh plus views on New Drug Approvals Blog in 233 countries...... , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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