5-BROMO-2-METHYL-2-PENTENE Chemical Properties

Melting point:

-102.35°C (estimate)

Boiling point:

152-154 °C (lit.)

Density 

1.217 g/mL at 25 °C (lit.)

refractive index 

n20/D 1.476(lit.)

Flash point:

73 °F

storage temp. 

2-8°C

form 

liquid

Specific Gravity

1.217

Appearance

Colorless to light yellow Liquid

Water Solubility 

Slightly miscible with water.

BRN 

1735749

InChI

InChI=1S/C6H11Br/c1-6(2)4-3-5-7/h4H,3,5H2,1-2H3

InChIKey

UNXURIHDFUQNOC-UHFFFAOYSA-N

SMILES

C/C(/C)=C\CCBr

Safety Information

Hazard Codes 

Xi

Risk Statements 

10-36/37/38

Safety Statements 

26-36

RIDADR 

UN 1993 3/PG 2

WGK Germany 

3

F 

10-23

Hazard Note 

Irritant

HazardClass 

3

PackingGroup 

III

HS Code 

29033990

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ALFA

5-BROMO-2-METHYL-2-PENTENE Usage And Synthesis

Uses

5-Bromo-2-methyl-2-pentene acts as a synthetic reagent, which is useful in the formation of sesqueterpenoid. It is also employed in the preparation of geranlol-3-14C. Further, it is used in the preparation of penifulvin A, which is a sesquiterpenoid with a novel dioxa-fenestrane structure.

Synthesis

1. 105 kg of THF solution of 12% methylmagnesium bromide (equivalent to 12.6 kg 100% concentration) was slowly added to a stainless steel reactor under brine bath cooling, maintaining the reaction temperature at 30-35°C. 2. 6.7 kg of cyclopropyl methyl ketone (II) was added dropwise to the reactor. 2. 6.7 kg of cyclopropyl methyl ketone (II) was added dropwise to the reactor, and after completion of the dropwise addition, the reaction mixture was stirred continuously at 30-35 °C for at least 1 hour. 3. the reaction mixture was cooled to 5-10 °C and then transferred to another enameled reactor pre-cooled to 0-10 °C containing 60 kg of 35% sulfuric acid. 4. the reaction mixture was warmed to 25-30 °C and maintained at this temperature for at least 15 minutes to ensure complete reaction. Subsequently, it was left to fully separate the two phases and remove the lower aqueous phase. 5. The organic phase was washed with 6.7 kg of softened water, stirred at 25-30 °C and left to stratify, again removing the lower aqueous phase. 6. Remove the solvent from the organic phase by vacuum distillation until an oily residue is obtained. To the residue was added 10.1 kg of THF and stirred until complete dissolution. 7. The resulting solution was transferred to a vessel of suitable capacity and prepared for the next stage of the reaction. 8. 8. 10 kg of the target product 5-bromo-2-methyl-2-pentene was finally obtained in 77% yield based on cyclopropyl methyl ketone (II).

References

[1] Chemistry - A European Journal, 2009, vol. 15, # 40, p. 10473 - 10485
[2] Organic and Biomolecular Chemistry, 2014, vol. 12, # 47, p. 9707 - 9715
[3] Organic Letters, 2006, vol. 8, # 24, p. 5421 - 5424
[4] European Journal of Organic Chemistry, 2006, # 14, p. 3181 - 3192
[5] Patent: US2009/43093, 2009, A1. Location in patent: Page/Page column 3

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