Anhydrous 5-Bromo-1-Pentene CAS 1119-51-3 Grignard Grade Low Water Liquid

Making the Grignard from 5-bromo-1-pentene is straightforward until water gets in the way. Fifty parts per million of moisture is enough to leave a cloudy magnesium hydroxide haze, eat into the yield and make the filtration slow. We dry this grade over a molecular sieve under argon, verify it by Karl Fischer, and fill it under the same argon blanket so the number on the certificate is the number in your flask.

Peroxide is the other number we watch. An alkene stored in air forms peroxides slowly, and those peroxides attack the magnesium surface and can give a violent initiation. This grade is held at 20 mg/kg peroxide or below, which is well inside what a normal Grignard charge can tolerate.

• Water 50 ppm maximum by Karl Fischer: clear Grignard solution with no hydroxide haze and no lost reagent
• Peroxide value 20 mg/kg maximum: predictable initiation, no runaway on the first addition of magnesium
• Argon filled, septum cap on 1 kg bottles: you can cannula transfer without opening the bottle to air
• Low alcohol content: no competing proton source during reagent formation
• Magnesium friendly purity: 99% minimum with the dibromoalkane kept under 0.5%, which otherwise consumes two equivalents of metal
• Drum headspace sieve option: dryness survives a long sea freight rather than decaying in transit

This is the grade for preparing 5-pentenylmagnesium bromide, for lithium halogen exchange, and for any organometallic step where the reagent is made in situ and the water budget is already tight.

Transfer by cannula or syringe through the septum, and keep the magnesium turnings dry and freshly opened. Initiate with a small portion and a little iodine or dibromoethane if the metal is old, then add the rest at a rate that keeps the flask at reflux without running away.

1 kg amber glass with a septum cap, 5 kg lined cans, and 25 kg drums with a headspace sieve for plant scale. Everything is argon filled and labelled with water content at release.

Store under argon between 5 and 25 degrees C. Flammable liquid with a flash point near 32 degrees C, so keep it away from ignition sources and use earthed containers when decanting.

COA reports assay, water by Karl Fischer, peroxide value, free alcohol, dibromoalkane, colour and density, with the GC trace. A sealed retention sample is held for 12 months under argon.

On request we can add an oxygen and moisture barrier bag to the drum, or supply a small cylinder of argon with the first order so the customer can re-blanket after each use.