From OpenWetWare
Revision as of 15:28, 21 March 2011 by Michael Wolfle (talk | contribs) (Solvent Distillation)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search


Home        Contact        Internal        People        Papers        Research        Teaching        Links        News        Construction       

Storage of Solvents in the Lab

We must try to mimimize the level of flammable solvents we hold in the lab. Make use of the main store for this. Label our Winchesters with our group name. We are able to deposit and remove solvents between 9 and 3.

In the lab, flammable solvents must be stored in the yellow flammable cabinets. The Winchesters must be standing upright, not on their sides. Keep flammable solvents separate from chlorinated solvents, and separate again from toxic solvents such as methanol. (note that flammable reagents are kept in other yellow flammables cabinets)

Chlorinated solvents are usually kept under a hood, together.

Solvent Distillation

We usually distil hexane on Wednesdays. One group member is responsible for this each week. If you are that person, make sure that you accurately assess the likely amount of hexane needed for the coming week, and you distil enough hexane. Usually 6 Winchesters is OK but ask around and check the level of stock in the store (on the laminated paper sheet in the lab). Once this is done, store some of the bottles (usually 3) in the store. If it's your week to distil, you also need to bring up Winchesters of other solvents (usually 2 Winchesters of each).

The further responsibilities of this person are to:

Solvent distillation rota:

(see also here:Todd Group Solvent Roster)

When Who
Mar 23 Soo
Mar 30 Michael
Apr 6 Anthony
Apr 13 Althea
Apr 20 Nilupa
Apr 27 Mingfeng
May 4 Swapnil
May 11 Soo

How to distill solvents

Before distilling solvent, attach the appropriate laminated solvent label to each heating mantle.

Carefully remove the fractionating column. Decant any remaining solvent from the flask into the appropriate waste container - try to retain the boiling chips. Don't worry about remaining solvent sticking to the insides of flasks - these will be removed in the distillation process. Pour the undistilled solvent into the flask (use a big funnel) and ensure that there are enough anti-bumping granules in the flask. Replace the fractionating column. Turn on the heating mantle (check the power point if the light doesn't turn up) to about 5 (for hexane), followed by water to the condenser.

The rest is high school chemistry: Watch the thermometer, discard lower fractions, collect desired fraction (e.g. dichloromethane at 40 degrees centigrade), and discard the upper fractions. There is a boiling point chart on the window.

Typically the first 100 mL (lower fractions) and last 100 mL (higher fractions) of solvent distillation is discarded. By this time, the temperature should have risen to that of the boiling point of the desired solvent. At this point you can collect the distillate using the large (5 L) conical flasks, or collect directly into the empty Winchesters and swap Winchesters as they fill up. Collection flasks and Winchesters need to be rinsed with some distillate before using for collection. CHECK THE STILLS PERIODICALLY WHILE THEY ARE DISTILLING. Do not let collection flasks/Winchesters overflow as this is wasteful and poses a serious fire risk. Do not let the stills boil dry, since this means you have collected high-boiling impurities, and have to start all over again. It is highly recommended that you set up alarms/timers to remind yourself to check the stills. When there is approx. 100 mL left to distill, cease collection. watching the thermometer will indicate when to stop collecting the solvent, i.e. stop collecting BEFORE the temperature rises. Turn off the heating mantle, both on the mantle itself and at the powerpoint. Leave the condenser taps on until the still is sufficiently cool.

In the event of accidental breakage of still glassware, take the broken part to the Level 5 service room immediately and ask Carlo or Bruce to order a replacement/repair. Everyone on Lv 5 research needs the stills and we cannot afford to have much downtime. Large-scale distillation equipment is highly specialised and takes quite some time to replace, so as a matter of courtesy, deal with it immediately and do not leave the problem to someone else.

Ordering Solvents

Go to the Main Store website (accessible on the School of Chemistry intranet only) and click on the button "Decanted Solvents" to view and order our staple lab solvents.

Print this form and take it with you to the Store (located behind the East Wing elevator, open 9-11 am and 2-3 pm weekdays).

Taking empty Winchesters down to the Main Store to swap with filled Winchesters

Empty bottles are stored on the Todd rack in the still room. Remove all "MHT Distilled" tags. All Winchesters must be transported to the store using an appropriate chemical carrier. For 1-2 Winchesters, hand held Winchester carriers may be used. They are located at the front of the Cornforth lab. For 2-8 Winchesters, they can go into milk crates, which are to be transported on trolley fitted with trays designed to hold spillages. Another trolley, fitted with large red plastic containers, may also be used. These trolleys are kept in front of the Level 5 service room. A maximum of 20 L (8 Winchesters) may be transported via the elevator at any one time. Safety glasses and ID cards are essential when visiting the Level 1 Main Store.

Correctly labelling Winchesters with distilled solvent

Label the Winchester by placing a laminated tag, labelled "MHT Distilled", around the bottleneck, and place it in the appropriate yellow flammable cabinets. There is a basket with the tags in the small stills area.

Booking the distillation session for the following week

When you have finished for the day, change the date on the booking sheet for the following week, as we aim to distil on the same day each week. Booking of the stills for distillation is done on the laminated sheets on the window of the still room. It is the responsibility of the person distilling to make a booking for the following week. If this is neglected, another group may take our booking, and we will soon find ourselves running low on distilled solvents and unable to perform experiments.

Obtaining Other Solvents from Stills

If we need small amounts of other solvents dried, we must use the stills operated by other groups. It is very important that you seek advice if you are uncertain of how to do this. You must use the stills carefully so as not to contaminate the solvent, and you must leave the stills in good condition. If you take a fair amount of solvent, you should ask whether you need to replenish the solvent, and where to get the solvent from. We'll soon have the solvent purification system, thankfully.