Stills for drying solvents shared with DOH group Alice Leung 08122016 Used for drying solvents THF Toluene Hexane Predried over KOH or molecular sieves 4 Å THF NEVER dry with KOH ID: 654937
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Slide1
Standard Operating Procedure:Stills for drying solvents(shared with DOH group)
Alice Leung
08/12/2016Slide2
Used for drying solvents:THF
Toluene
HexanePre-dried over KOH or molecular sieves (4 Å)THF – NEVER dry with KOH, generation of peroxide possibleRefluxed over sodium/benzophenone (indicator):Blue/purple = DRYYellow/orange = WETHexane – indicator sparingly soluble (triglyme)
What do they do?Slide3
Indicator of dryness of stillsHazard – SODIUM under reflux in flammable solvents!
Build up of
NaOH – stills must be changed every 3-4 monthsSodium/benzophenone indicatordeep blue radical anionpurple dianionSlide4
YOU MUST BE A TRAINED USER TO OPERATE SOLVENT STILLSBefore use…
Trained users from the group
Alice Leung & Arron DeacyTHF stills maintained by DOH group:Dr Jean-Charles (JC) BuffetDr Zoë TurnerDr Sandy KilpatrickSlide5
Stills set up in CRL (room opposite lab S8)
O’Hare group
(THF)Goicoechea group(THF)Aldridge group(…..)Water ON (before switching stills on)THF stills connected to same N2 supply
Log bookSlide6
Set up (stills on – N2 flow and water on)
N
2 inN2 out
Water condenser
Collection tap
Paraffin bubbler
Mercury bubbler (ONLY for collection)
Collection funnelSlide7
Solvent MUST be refluxing before collectionSwitch off Goicoechea stills (if on)
Inform a member in
Goicoechea group (unplug from wall socket)Collection tap – horizontal Allow 20-30 mins for condensation of THF (250-300 mL) in condenserOnce collectedSWITCH OFF power by removing plug from the main on wallAllow to cool (1-1.5 hrs)Collection of THFCollection tap - HORIZONTALSlide8
Collection of THF – stills cooled
ONLY
ampoules with Young’s tab and metal cannula can be used(1) Switch N2 bubbler from parrafin to mercuryHigh pressure to push solvent out through need into ampoule(2) Purge cannula and ampoule using stills N2 flow (ref. SPS collection) then collectCollection done(3) collection tap returned to vertical position(4) bubbler slowly switched back to parrifin
1
2
3
4Slide9
Collection finished
N
2 inN2 outWater condenserParaffin bubblerSwitch both O’Hare and Goicoechea (if it was on before) stills back on
NO exposed Na seenH
2O flow onN2 flow onINFORM both groups that solvent collection is done and stills are onSlide10
Always write in log book to what you have done with both THF stillsMUST be counter-signed by O’Hare (JC, Zoë or Sandy) and Goicoechea group (David Lo)
Remember…
Do’sCheck with O’Hare group that it is good to collect THFPreferably collect towards end of weekInform Goicoechea groupUnplug heating mantles from the main wall socketsNo chance of accidentally switching stills back onWater is always on when stills is on
Don’ts
Let stills boiled dry!!!
Use mercury bubbler when refluxing
Let air get into system
Overfill stills
Leave stills on for collection for a long period of time when collection funnel is fullSlide11
PLEASE ASK!If in doubt…Slide12
Disconnect stills from set up carefully without letting air inKeep stills under N2 atmosphereUnder a dynamic flow of N2 and stills keep cold using ice bath
Slowly
add in IPA/toluene with stirring until stills turn yellow/orangeSlowly add in IPA/waterWarm stills mixture to room temperatureExpose stills mixture to air and stir overnightDispose of the mixture as hydrocarbon wasteProcedure MUST be performed in fumehood Disposal of stills