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Impurities

SynThink is a trusted producer and supplier of Pharmaceutical Reference Standards, including Impurity Standards. These materials are essential for pharmaceutical companies conducting research into the quality, stability, and biological safety of drug products. We maintain a robust inventory of API impurities, ready to support your development and regulatory needs.

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Allopurinol, Impurities

4-Chloro-2,6-dimethoxypyrimidine-5-carbaldehyde

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CAS No.

: 134221-52-6

Mol F.

: C7H7ClN2O3

Mol W.

: 202.59

Cat No.

: SA28913

Dapagliflozin, Impurities

4-Chloro-3-(4-ethoxybenzyl)phenol

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CAS No.

: 1408077-50-8

Mol F.

: C15H15ClO2

Mol W.

: 262.73

Cat No.

: SA15051

Building Blocks, Impurities

4-Chloro-3-(trifluoromethyl)aniline

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CAS No.

: 320-51-4

Mol F.

: C7H5ClF3N

Mol W.

: 195.57

Cat No.

: SB10718

Impurities, Nintedanib

4-Chloro-3-nitrobenzoic acid methyl ester

$85.00 25 mg

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CAS No.

: 14719-83-6

Mol F.

: C8H6ClNO4

Mol W.

: 215.59

Cat No.

: SA22516

Erlotinib, Impurities

4-Chloro-6-(2-chloroethoxy)-7-(2-methoxyethoxy)quinazoline

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CAS No.

: 183322-19-2

Mol F.

: C13H14Cl2N2O3

Mol W.

: 317.16

Cat No.

: SA25221

Impurities, Lorcaserin

4-Chloro-N-(2-hydroxypropyl)benzeneacetamide

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CAS No.

: 1030624-36-2

Mol F.

: C11H14ClNO2

Mol W.

: 227.69

Cat No.

: SA18810

Impurities, Sumatriptan

4-Chlorobutyraldehyde Diethyl Acetal

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CAS No.

: 6139-83-9

Mol F.

: C8H17ClO2

Mol W.

: 180.67

Cat No.

: SA34817

Nizatidine

4-Chloromethyl-2-Dimethylamino methyl thiazole

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CAS No.

: 82586-71-8

Mol F.

: C7H11ClN2S

Mol W.

: 190.7

Cat No.

: SA34414

Impurities, Olmesartan Medoxomil

4-Chloromethyl-5-Methyl-1,3-dioxol-2-one

$125.00 25 mg

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CAS No.

: 80841-78-7

Mol F.

: C5H5ClO3

Mol W.

: 148.54

Cat No.

: SA17729

Clotrimazole, Impurities

4-Chlorotrityl chloride

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CAS No.

: 27023-37-6

Mol F.

: C19H14Cl2

Mol W.

: 313.22

Cat No.

: SA11607

Impurities, Raltegravir

4-Defluoro 4-Methoxy Raltegravir

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CAS No.

Mol F.

: C21H24N6O6

Mol W.

: 456.45

Cat No.

: SA25608

Impurities, Trimethoprim

4-Demethyltrimethoprim

$95.00 25 mg

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CAS No.

: 21253-58-7

Mol F.

: C13H16N4O3

Mol W.

: 276.29

Cat No.

: SA27112

Efinaconazole, Impurities

4-desfluoro 4 (1,2,4-triazol) (R,S)-Efinaconazole Epoxide

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CAS No.

: NA

Mol F.

: C14H13FN6O

Mol W.

: 300.29000000000002

Cat No.

: SA23600

Efinaconazole, Impurities

4-Desmethylene-4-hydroxymethyl-efinaconazole

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CAS No.

: NA

Mol F.

: C18H24F2N4O2

Mol W.

: 366.41

Cat No.

: SA23606

Brimonidine, Impurities

4-Dimethylaminopyridine; Brimonidine Dimethyl Amino Pyridine

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CAS No.

: 1122-58-3

Mol F.

: C7H10N2

Mol W.

: 122.17

Cat No.

: SA20727

Impurities, Osimertinib

4-Fluoro-2-methoxy-5-nitroaniline

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CAS No.

: 1075705-01-9

Mol F.

: C7H7FN2O3

Mol W.

: 186.14

Cat No.

: SA44701

Impurities, Paroxetine

4-Fluoro-4’-formylbiphenyl

$100.00 25 mg

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CAS No.

: 60992-98-5

Mol F.

: C₁₃H₉FO

Mol W.

: 200.21

Cat No.

: SA18315

Impurities, Intermediates

4-Formyl Phenylboronic Acid MIDA Ester

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CAS No.

: 1072960-66-7

Mol F.

: C12H12BNO5

Mol W.

: 261.04

Cat No.

: SRC900140

Cariprazine, Impurities

4-Hydroxy 2,3-Dichlorophenyl Cariprazine

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CAS No.

: 1084891-95-1

Mol F.

: C21H32Cl2N4O2

Mol W.

: 443.41

Cat No.

: SA39708

Impurities, Raloxifene

4-Hydroxy benzothiophene Raloxifene

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CAS No.

: 185416-01-7

Mol F.

: C28H27NO4S

Mol W.

: 473.58

Cat No.

: SA24912

Darunavir, Impurities

4-Hydroxy Darunavir

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CAS No.

: 313682-97-2

Mol F.

: C27H37N3O8S

Mol W.

: 563.66

Cat No.

: SA39407

Donepezil, Impurities

4-Hydroxy Donepezil Impurity

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CAS No.

: 197010-22-3

Mol F.

: C24H29NO4

Mol W.

: 395.49

Cat No.

: SA34317

Erlotinib, Impurities

4-Hydroxy Erlotinib

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CAS No.

: 882420-22-6

Mol F.

: C22H23N3O5

Mol W.

: 409.44

Cat No.

: SA25201

Ethinylestradiol, Impurities

4-Hydroxy Ethinylestradiol

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CAS No.

: 50394-90-6

Mol F.

: C20H24O3

Mol W.

: 312.4

Cat No.

: SA13126

Fingolimod, Impurities

4-Hydroxy Fingolimod Impurity

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CAS No.

: 268557-51-3(HCl);162361-49-1(Base)

Mol F.

: C19H34ClNO3

Mol W.

: 359.93

Cat No.

: SA34504

Ibrutinib, Impurities

4-Hydroxy Ibrutinib

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CAS No.

: 1288339-18-3

Mol F.

: C25H24N6O3

Mol W.

: 456.5

Cat No.

: SA47412

Impurities, Intermediates

4-Hydroxy Phenylboronic Acid MIDA ester

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CAS No.

: 1613586-40-5

Mol F.

: C11H12BNO5

Mol W.

: 249.03

Cat No.

: SRC900139

Impurities, Trimetazidine

4-Hydroxy Trimetazidine Impurity

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CAS No.

Mol F.

: C13H20N2O3

Mol W.

: 252.31

Cat No.

: SA35111

Impurities, Trimethoprim

4-Hydroxy Trimethoprim

$495.00 25 mg

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CAS No.

: 112678-48-5

Mol F.

: C14H18N4O4

Mol W.

: 306.32

Cat No.

: SA27114

Impurities, Valsartan

4-Hydroxy Valsartan

$995.00 100 mg

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CAS No.

: 188259-69-0

Mol F.

: C24H29N5O4

Mol W.

: 451.52

Cat No.

: SA33305

Allopurinol, Impurities

4-Hydroxy-1-phenylpyrazolo[3,4-d]pyrimidine

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CAS No.

: 21314-17-0

Mol F.

: C11H8N4O

Mol W.

: 212.21

Cat No.

: SA28915

Impurities, Trimetazidine

4-hydroxy-2,3-dimethoxybenzaldehyde

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CAS No.

: 69471-05-2

Mol F.

: C9H10O4

Mol W.

: 182.17

Cat No.

: SA35110

Impurities, Leflunomide

4-Hydroxy-Teriflunomide

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CAS No.

: 1058722-45-4

Mol F.

: C12H9F3N2O3

Mol W.

: 286.20999999999998

Cat No.

: SA21813

Clomifene, Impurities

4-Hydroxy-α,β-diphenylbenzeneethanol

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CAS No.

: 94549-25-4

Mol F.

: C20H18O2

Mol W.

: 290.35

Cat No.

: SA21711

Efinaconazole, Impurities

4-Hydroxymethyl-1-benzoyl Piperidine

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CAS No.

: 19980-00-8

Mol F.

: C13H17NO2

Mol W.

: 219.58

Cat No.

: SA23613

Impurities, Rilpivirine

4-Iodo-2,6-bis(methoxymethyl)aniline

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CAS No.

: NA

Mol F.

: C10H14INO2

Mol W.

: 307.13

Cat No.

: SA25405

Impurities, Omeprazole

4-Methoxy-2-nitroaniline

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CAS No.

: 96-96-8

Mol F.

: C7H8N2O3

Mol W.

: 168.15

Cat No.

: SA19401

Impurities, Ranolazine

4-Methoxyphenol

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CAS No.

: 150-76-5

Mol F.

: C7H8O2

Mol W.

: 124.14

Cat No.

: SA26810

Apixaban, Impurities

4-Methoxyphenylhydrazine Hydrochloride

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CAS No.

: 19501-58-7

Mol F.

: C7H10N2O·HCl

Mol W.

: 174.63

Cat No.

: SA39927

Apixaban, Impurities

4-Methyl-5-chlorovaleroyl Chloride

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CAS No.

: 813452-05-0

Mol F.

: C6H10Cl2O

Mol W.

: 169.05

Cat No.

: SA39956

Impurities, Pazopanib

4-Methyloxidoamino Pazopanib

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CAS No.

: 1821666-73-2

Mol F.

: C21H23N7O3S

Mol W.

: 453.5

Cat No.

: SA51316

Impurities, Lenalidomide

4-Nitro Lenalidomide Impurity

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CAS No.

: 827026-45-9

Mol F.

: C13H11N3O5

Mol W.

: 289.24

Cat No.

: SA34105

Sulfamethoxazole

4-Nitro Sulfamethoxazole

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CAS No.

: 29699-89-6

Mol F.

: C10H9N3O5S

Mol W.

: 283.26

Cat No.

: SA25508

Impurities, Sulfamethoxazole

4-Nitroso Sulfamethoxazole

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CAS No.

: 131549-85-4

Mol F.

: C10H9N3O4S

Mol W.

: 267.26

Cat No.

: SA25507

Ezetimibe, Impurities

4-O-Methylphenyl Ezetimibe Ketone

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CAS No.

: 190595-65-4

Mol F.

: C31H25F2NO3

Mol W.

: 497.53

Cat No.

: SA14848

Dolutegravir, Impurities

4-Oxo-3-[(phenylmethyl)oxy]-4H-pyran-2-carboxylic Acid

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CAS No.

: 119736-16-2

Mol F.

: C13H10O5

Mol W.

: 246.22

Cat No.

: SA20225

Dolutegravir, Impurities

4-Oxo-4H-pyran-2,5-dicarboxylic Acid 2,5-Diethyl Ester

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CAS No.

: 1246616-74-9

Mol F.

: C11H12O6

Mol W.

: 240.21

Cat No.

: SA20226

Brinzolamide, Impurities

4-Oxobrinzolamide Derivative

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CAS No.

: 154127-41-0

Mol F.

: C10H14N2O6S3

Mol W.

: 354.4

Cat No.

: SA47208

Apixaban, Impurities

4-Pentenoyl chloride

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CAS No.

: 39716-58-0

Mol F.

: C5H7ClO

Mol W.

: 118.56

Cat No.

: SA39957

Bosentan, Impurities

4-tert-Butylbenzenesulfonamide

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CAS No.

: 6292-59-7

Mol F.

: C10H15NO2S

Mol W.

: 213.3

Cat No.

: SA28604