13808-64-5

Basic information

• Product Name: 4-Bromo-3-methylpyrazole
• Synonyms: TIMTEC-BB SBB003957;4-BROMO-3-METHYLPYRAZOLE;4-BROMO-3-METHYL-1H-PYRAZOLE;3-Methyl-4-bromopyrazole;4-Bromo-3-methylpyrazole,97%;4-BROMO-3-METHYLPYRAZOLE 97%;1H-Pyrazole, 4-bromo-3-methyl-;3-Methyl-4-bromo-1H-pyrazole
• CAS NO: 13808-64-5
• Molecular Formula: C₄H₅BrN₂
• Molecular Weight: 161
• EINECS: 237-456-7
• Product Categories: Pyrazines;pharmacetical;Building Blocks;Halogenated Heterocycles;Heterocyclic Building Blocks;Pyrazoles;PyrazolesHeterocyclic Building Blocks
• Mol File: 13808-64-5.mol
• Article Data: 2

Chemical Properties

• Melting Point: 77-79°C
• Boiling Point: 259.9 °C at 760 mmHg
• Flash Point: 111 °C
• Appearance: White to cream/Powder
• Density: 1.5638
• Vapor Pressure: 0.0204mmHg at 25°C
• Refractive Index: 1.5182 (estimate)
• Storage Temp.: Keep in dark place,Inert atmosphere,Room temperature
• Solubility: methanol: soluble0.25g/5mL, clear, colorless to yellow
• PKA: 13.27±0.50(Predicted)
• CAS DataBase Reference: 4-Bromo-3-methylpyrazole(CAS DataBase Reference)
• NIST Chemistry Reference: 4-Bromo-3-methylpyrazole(13808-64-5)
• EPA Substance Registry System: 4-Bromo-3-methylpyrazole(13808-64-5)

Safety Data

• Hazard Codes: Xi
• Statements: 36/37/38
• Safety Statements: 37/39-26
• WGK Germany: 3
• HazardClass: IRRITANT
• Hazardous Substances Data: 13808-64-5(Hazardous Substances Data)

Usage

Chemical Properties

white to cream-colored powder

Uses

Different sources of media describe the Uses of 13808-64-5 differently. You can refer to the following data:
1. 4-Bromo-3-methyl-1H-pyrazole may be used in chemical synthesis.
2. 4-Bromo-3-methylpyrazole is an intermdiate used to prepare substituted piperidines as potent, selective, CNS-penetrant α4β2 nicotinic acetylcholine receptor potentiators. It is also used to prepare small molecular B2 receptor antagonists.

InChI:InChI=1/C4H5BrN2/c1-3-4(5)2-6-7-3/h2H,1H3,(H,6,7)

Synthetic route

4-bromo-3-methyl-1-phenylsulphonylpyrazole (130874-31-6) → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
With potassium hydroxide In methanol for 1h; Heating;	83%
With potassium hydroxide In methanol for 1h; Heating; other 4-bromo-1-phenylsulphonylpyrazoles;	83%

3-Methylpyrazole (1453-58-3) → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
Stage #1: 3-Methylpyrazole With N-Bromosuccinimide In N,N-dimethyl-formamide at 60℃; Continuous flow reactor; Stage #2: With water; acetic acid In N,N-dimethyl-formamide	49%

3(resp. 5)-methyl-pyrazole → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
With water; bromine

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + di-tert-butyl dicarbonate (24424-99-5) → tert-butyl 4-bromo-3-methyl-1H-pyrazole-1-carboxylate (1021919-24-3)

Conditions	Yield
With sodium hydroxide In 1,4-dioxane at 20℃;	100%
With sodium carbonate In dichloromethane; water for 2.5h;
With sodium carbonate In dichloromethane at 20℃; for 16h;
With dmap; triethylamine In acetonitrile at 20℃;	0.32 g

3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (58-08-2) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4,5,8-tris(4-bromo-3-methyl-1H-pyrazol-1-yl)-1,3,7-trimethyl-3,4,5,7-tetrahydro-1H-purine-2,6-dione

Conditions	Yield
With tetrabutylammonium tetrafluoroborate In acetonitrile at 45℃; for 10h; Inert atmosphere; Electrochemical reaction; Green chemistry; diastereoselective reaction;	99%

9-borabicyclo[3.3.1]nonane dimer (21205-91-4) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) + potassium hydride → potassium[bis(3-Me-4-Br-pyrazolyl)borate(C8H14)]

Conditions	Yield
In toluene for 3h; Inert atmosphere; Schlenk technique; Reflux;	96%

4-oxanyl methanesulfonate (134419-59-3) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 10h;	88%

triisopropylsilyl chloride (13154-24-0) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-(triisopropylsilyl)-1H-pyrazole

Conditions	Yield
With triethylamine In dichloromethane for 72h; Reflux;	86.1%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + carbon dioxide (124-38-9) + methyl iodide (74-88-4) → methyl 4-bromo-3-methyl-1H-pyrazole-1-carboxylate (1207853-38-0)

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole; carbon dioxide With cesium hydroxide; (hydroxido){N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene}copper(I) In tetrahydrofuran at 40℃; under 1125.11 Torr; for 0.204167h; Inert atmosphere; Stage #2: methyl iodide In tetrahydrofuran Inert atmosphere; regioselective reaction;	85%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + phenylboronic acid (98-80-6) → 3-Methyl-4-phenyl-1H-pyrazole (13788-84-6)

Conditions	Yield
With palladium diacetate; potassium carbonate; catacxium A In 1,4-dioxane; water at 100℃; for 12h; Inert atmosphere;	84%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1,3,5-trimethyl-benzene (108-67-8) → 4-bromo-1-mesityl-3-methyl-1H-pyrazole

Conditions	Yield
With C24H42N3(1+)*ClO4(1-); lithium perchlorate; acetic acid In acetonitrile at 20℃; for 72h; Electrochemical reaction; Sealed tube; Irradiation;	83%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + benzenesulfonyl chloride (98-09-9) → 4-bromo-3-methyl-1-phenylsulphonylpyrazole (130874-31-6)

Conditions	Yield
With pyridine for 2h; Heating;	82%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + phenylboronic acid (98-80-6) → 4-bromo-3-methyl-1-phenyl-1H-pyrazole (50877-45-7)

Conditions	Yield
With pyridine; oxygen; copper diacetate In dichloromethane at 20℃; for 24h;	82%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + dimethylamino sulfonyl chloride (13360-57-1) → 4-bromo-3-methyl-pyrazole-1-sulphonic acid dimethylamide (882689-55-6)

Conditions	Yield
With 1,4-diaza-bicyclo[2.2.2]octane In acetonitrile at 20℃; for 6h;	81%
With 1,4-diaza-bicyclo[2.2.2]octane In acetonitrile at 20℃; for 6h;	81%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 0.5h; Stage #2: dimethylamino sulfonyl chloride In N,N-dimethyl-formamide; mineral oil at 0 - 20℃;	54%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With potassium tert-butylate In tetrahydrofuran at 20℃; for 0.333333h; Stage #2: dimethylamino sulfonyl chloride In tetrahydrofuran
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 0 - 20℃; for 1.25h; Stage #2: dimethylamino sulfonyl chloride In N,N-dimethyl-formamide at 0 - 20℃; for 3.25h;

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + benzyl bromide (100-39-0) → 1-benzyl-4-bromo-3-methyl-1H-pyrazole

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 20℃; for 0.5h; Inert atmosphere; Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 0 - 20℃;	80%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: benzyl bromide In tetrahydrofuran at 0 - 15℃; for 1h;	60%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: benzyl bromide In tetrahydrofuran at 0 - 15℃; for 1h;	60%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 4-methoxy-phenol (150-76-5) → 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol

Conditions	Yield
With dipotassium peroxodisulfate In acetonitrile at 80℃; for 5h; Inert atmosphere; Schlenk technique;	76%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + [Ru(2,2′-bipyridine-6,6′-dicarboxylate)((CH3)2SO)2] (1357927-37-7) → [Ru(2,2′-bipyridine-6,6′-dicarboxylate)(DMSO)(4-bromo-3-methyl-pyrazole)2]

Conditions	Yield
In methanol for 0.333333h; Reflux; Inert atmosphere;	75%

3-bromomethyl-3-methyloxetane (78385-26-9) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-((3-methyloxetan-3-yl)methyl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 1.5h; Microwave irradiation;	74.9%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + trityl chloride (76-83-5) → 4-bromo-3-methyl-1-trityl-1H-pyrazole (474706-49-5)

Conditions	Yield
With triethylamine In chloroform at 20℃; Inert atmosphere;	73%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol → 2,6-bis(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol

Conditions	Yield
With dipotassium peroxodisulfate In acetonitrile at 80℃; for 5h; Inert atmosphere; Schlenk technique;	72%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 2,2,2-trifluoroethyl trifluoromethanesulphonate (6226-25-1) → 4-bromo-3-methyl-1-(2,2,2-trifluoroethyl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 0.5h; Microwave irradiation;	68.4%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + ethyl bromoacetate (105-36-2) → ethyl 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)acetate

Conditions	Yield
With sodium hydride; potassium iodide In N,N-dimethyl-formamide; mineral oil at 80℃; for 12h;	68%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + [Ru(2,2′-bipyridine-6,6′-dicarboxylate)((CH3)2SO)2] (1357927-37-7) → [Ru(2,2′-bipyridine-6,6′-dicarboxylate)(4-bromo-3-methyl-pyrazole)3]

Conditions	Yield
In methanol for 6h; Reflux; Inert atmosphere;	68%

1-methyl-2(1H)-quinoxalinone (6479-18-1) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 3-(4-bromo-3-methyl-1H-pyrazol-1-yl)-1-methylquinoxalin-2(1H)-one

Conditions	Yield
With air In acetonitrile at 20℃; for 20h; Irradiation;	60%

2-iodo-propane (75-30-9) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-1-isopropyl-3-methyl-1H-pyrazole (1215295-87-6)

Conditions	Yield
With caesium carbonate In acetonitrile at 90℃; for 12h;	56%
With caesium carbonate In acetonitrile at 90℃; for 12h;	56%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate (141699-59-4) → tert-butyl 4-(4-bromo-5-methyl-1H-pyrazol-1-yl)piperidine-1-carboxylate (1076223-99-8) + tert-butyl 4-(4-bromo-3-methyl-1H-pyrazol-1-yl)piperidine-1-carboxylate (1092500-89-4)

Conditions	Yield
With sodium hydride In mineral oil at 70℃;	A 27% B 53%
With sodium hydride In N,N-dimethyl acetamide; mineral oil at 70℃;	A 27% B 53%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 0℃; for 1h; Stage #2: 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate In N,N-dimethyl-formamide at 95℃; for 1h;
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 1h; Stage #2: 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate In N,N-dimethyl-formamide; mineral oil at 90℃; for 4h;

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1-Chloro-4-fluorobenzene (352-33-0) → 4-bromo-1-(4-chlorophenyl)-3-methyl-1H-pyrazole

Conditions	Yield
With tetrabutylammonium tetrafluoroborate; acetic acid; 2,3-dicyano-5,6-dichloro-p-benzoquinone In acetonitrile at 20℃; for 36h; Sealed tube; Inert atmosphere; Irradiation; Electrolysis;	52%

2-bromo-5-methyl-1,3-thiazole (41731-23-1) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → C8H8BrN3S

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 20℃; for 0.5h; Stage #2: 2-bromo-5-methyl-1,3-thiazole In N,N-dimethyl-formamide at 20 - 90℃;	50%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 4-bromo-2-(n-propyl)pyridine (98420-99-6) → 4-(4-bromo-3-methyl-1H-pyrazol-1-yl)-2-propylpyridine

Conditions	Yield
With copper(l) iodide; caesium carbonate In N,N-dimethyl acetamide at 1140℃; for 6h; Sealed tube;	49%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + (2-trimethylethylsilylethoxy)methyl chloride (76513-69-4) → 2-[(4-bromo-3-methylpyrazol-1-yl)methoxy]ethyltrimethylsilane

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: (2-trimethylethylsilylethoxy)methyl chloride In tetrahydrofuran at 25℃; for 4h;	44.22%

2-bromo-1,3-thiazole (3034-53-5) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → C7H6BrN3S

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 20℃; for 0.5h; Stage #2: 2-bromo-1,3-thiazole In N,N-dimethyl-formamide at 20 - 90℃;	42%

Upstream product

• 1453-58-3 3-Methylpyrazole 
• 130874-31-6 4-bromo-3-methyl-1-phenylsulphonylpyrazole 

Downstream Products

• 5775-82-6 4-bromo-1,3-dimethyl-1H-pyrazole 
• 5775-86-0 4-bromo-1,5-dimethyl-1H-pyrazole 
• 5932-19-4 3,4-dibromo-5-methylpyrazole 
• 5334-39-4 3-methyl-4-nitro-1H-pyrazole 
• 1453-58-3 3-Methylpyrazole 
• 13788-84-6 3-Methyl-4-phenyl-1H-pyrazole 
• 1092563-68-2 tert-butyl 4-(3-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl)piperidine-1-carboxylate 
• 1092563-67-1 4-[5-methyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyrazol-1-yl]-piperidine-1-carboxylic acid tert-butyl ester 
• 474706-49-5 4-bromo-3-methyl-1-trityl-1H-pyrazole 

Relevant articles and documents

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Chemists working in a pilot plant often face safety issues during scale-up operations. With the help of emerging microfluidic applications and microdevices, running hazardous, highly exothermic or potentially unstable reactions can be easily transposed into a safe continuous flow mode. This paper describes how a potentially hazardous pyrazole nitration and the bromination of a variety of electron-rich heteroaromatic substrates were efficiently performed using a cheap and easily available system for bench chemists. Advantages of the continuous flow mode in organic synthetic chemistry will be exemplified by the large-scale production of raw materials under safe, green and reproducible conditions.