00:00:00.030 ok so now we're going to look at rotary 00:00:02.30000:00:02.310 evaporation so we've got this solvent 00:00:05.80900:00:05.819 and we've got our compound in solvent 00:00:07.88000:00:07.890 and we need to get rid of the solvent so 00:00:10.28000:00:10.290 we use a rotary evaporator such as one 00:00:13.00900:00:13.019 of these and we're gonna place our 00:00:15.53000:00:15.540 sample in this flask flask goes on this 00:00:19.58000:00:19.590 end here and it'll be clipped and 00:00:25.58000:00:25.590 essentially what we have is a 00:00:26.75000:00:26.760 distillation setup so we have the flask 00:00:30.16900:00:30.179 here we use the water bath to raise the 00:00:32.74900:00:32.759 temperature and then we have the vacuum 00:00:39.77000:00:39.780 over here we have a condenser here to 00:00:43.61000:00:43.620 call the solvent that's coming off which 00:00:47.69000:00:47.700 will then be collected in this trap here 00:00:53.85000:00:53.860 over here at this point we have a tap 00:00:58.56000:00:58.570 which allows us to bleed air into the 00:01:01.26000:01:01.270 system so in order to set it up first 00:01:05.28000:01:05.290 thing we're going to do is make sure we 00:01:06.72000:01:06.730 switch it on and here we can then set 00:01:10.35000:01:10.360 the temperature essentially for most 00:01:13.29000:01:13.300 organic solvents we're gonna 140 degrees 00:01:16.32000:01:16.330 will do very nicely and then we're going 00:01:19.38000:01:19.390 to turn on the cooling water so it 00:01:25.32000:01:25.330 doesn't want to be too fast running 00:01:30.51000:01:30.520 through system 00:01:38.46900:01:38.479 you do want to make sure that the 00:01:42.39900:01:42.409 receiver flask is empty should have been 00:01:45.95000:01:45.960 emptied by the last person just check 00:01:47.89900:01:47.909 that because the last thing you want is 00:01:49.81900:01:49.829 to if your comp accidentally bumps and 00:01:52.66900:01:52.679 is pulled up over into this flask you 00:01:55.10000:01:55.110 don't want to be contaminated with 00:01:56.63000:01:56.640 anything anyone else has been using so 00:01:59.12000:01:59.130 we're going to pour our compound into 00:02:03.91900:02:03.929 the flask and then we're gonna carefully 00:02:09.07000:02:09.080 clip the Platts flask in place okay be 00:02:14.60000:02:14.610 particularly careful with heavy solvent 00:02:16.52000:02:16.530 such DCM because they are very dense and 00:02:18.94900:02:18.959 that can cause this to fall down so 00:02:21.62000:02:21.630 we're gonna make sure that this tap here 00:02:24.65000:02:24.660 is open and then follow the vacuum 00:02:28.91000:02:28.920 through round and we're going to turn on 00:02:34.06900:02:34.079 the vacuum 00:02:45.86000:02:45.870 and now we're going to start to rotate 00:02:49.88000:02:49.890 the flask and we're going to turn it 00:02:52.91000:02:52.920 till it's about two-thirds of one 00:02:56.80900:02:56.819 o'clock position keeping our hand 00:02:59.41000:02:59.420 underneath here just to make sure it can 00:03:03.31900:03:03.329 very tape gently against that it's not 00:03:05.53900:03:05.549 going to fall in and then we start close 00:03:09.25900:03:09.269 the tap so we turn that tap so it's 00:03:13.28000:03:13.290 closing and keep an eye on that solvent 00:03:17.03000:03:17.040 so we can see it's starting to evaporate 00:03:18.61900:03:18.629 so this is dichloromethane which has a 00:03:20.39000:03:20.400 very low boiling point anyway it's a 00:03:24.31900:03:24.329 boiling point four to five because it 00:03:26.33000:03:26.340 doesn't take much and now you can see 00:03:29.50900:03:29.519 we've got the tap closed this is 00:03:32.86900:03:32.879 rotating it's bubbling away nicely and 00:03:34.86900:03:34.879 you can see on the glass this 00:03:37.49000:03:37.500 condensation starting to form from 00:03:39.17000:03:39.180 evaporation once that's going like that 00:03:42.00900:03:42.019 we then slowly use 00:03:48.66000:03:48.670 this to lower the flats just so what a 00:03:53.94000:03:53.950 portion now is in the water bath you 00:03:57.66000:03:57.670 don't need the whole flask in the water 00:03:58.94900:03:58.959 bath just that better and we see it 00:04:01.47000:04:01.480 starting to evaporate we can turn up the 00:04:05.05900:04:05.069 speed the reason why we're rotating the 00:04:09.51000:04:09.520 flask is to ensure that increases the 00:04:12.42000:04:12.430 surface area as the solids rotated and 00:04:15.80900:04:15.819 flung out by centripetal force around 00:04:17.58000:04:17.590 the sides of the flask and it also means 00:04:20.49000:04:20.500 that as its evaporating it also stops it 00:04:23.52000:04:23.530 from boiling and bumping and that's when 00:04:26.82000:04:26.830 essentially it jumps from this side over 00:04:30.33000:04:30.340 to here because the vacuums built up and 00:04:32.54000:04:32.550 the solvent explosively evaporates very 00:04:37.23000:04:37.240 quickly so we're going to leave that to 00:04:40.85000:04:40.860 evaporate nicely there 00:04:48.10000:04:48.110 laughs racing away 00:05:02.07000:05:02.080 okay so we've got to the end of our 00:05:04.29000:05:04.300 evaporation you'll now see that thinks 00:05:08.08900:05:08.099 all the solvent is evaporated 00:05:09.68900:05:09.699 everything's gone slow that down stop 00:05:14.10000:05:14.110 and then we're gonna raise it up out of 00:05:18.71900:05:18.729 the bath next thing to do this is to 00:05:22.64900:05:22.659 open this tap company selecting vacuum 00:05:28.74000:05:28.750 off 00:05:36.89000:05:36.900 what tonight games off we then unclip 00:05:44.32000:05:44.330 remove and then you'll want to keep the 00:05:49.31000:05:49.320 flask or wipe with some b-roll in order 00:05:53.36000:05:53.370 you have to dry fast one very important 00:05:57.08000:05:57.090 thing to remember is that if you are 00:05:59.46900:05:59.479 preparing sample is to weigh the flask 00:06:03.14000:06:03.150 before you put anything into it and that 00:06:07.07000:06:07.080 means you can weigh the flask in 00:06:08.24000:06:08.250 afterwards no wait and you can get the 00:06:10.82000:06:10.830 way to the solid that's in your flask 00:06:13.27000:06:13.280 final thing to do then is switch off 00:06:18.49000:06:18.500 switch off and then take your the 00:06:23.71900:06:23.729 reciever flask unscrew remove this and 00:06:30.32000:06:30.330 if there's any solvent in here there 00:06:32.45000:06:32.460 isn't in this case because DCM it's very 00:06:34.19000:06:34.200 low boiling and the house vacuum is very 00:06:36.52900:06:36.539 high it's a very good vacuum but it's to 00:06:40.40000:06:40.410 make sure you do empty anything that 00:06:43.07000:06:43.080 you've collected in the receiver flask 00:06:44.50000:06:44.510 negative here this back on tighten the 00:06:50.27000:06:50.280 screw and there we go got your compound
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