Todd:Solvents

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Storage of Solvents in the Lab

We must try to mimimize the level of flammable solvents we hold in the lab.

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.

Chlorinated solvents and non-flammable solvents are kept under the toxics fumehood.

Ordering Solvents

To order a solvents from UCL School of Pharmacy Stores, you need to submit an order form for your desired solvents before 1PM for collection at 3PM.

Dry Solvents

Dry solvents are available in G25 in the Dry Solvents cabinet - this is located near the dishwasher.

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.