[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:00.66,Default,,0000,0000,0000,,
Dialogue: 0,0:00:00.66,0:00:02.34,Default,,0000,0000,0000,,Fischer projections\Nare another way
Dialogue: 0,0:00:02.34,0:00:04.66,Default,,0000,0000,0000,,of visualizing molecules\Nin three dimensions.
Dialogue: 0,0:00:04.66,0:00:07.57,Default,,0000,0000,0000,,And let's use the\Nexample of lactic acid.
Dialogue: 0,0:00:07.57,0:00:09.07,Default,,0000,0000,0000,,It's called lactic\Nacid since it has
Dialogue: 0,0:00:09.07,0:00:12.20,Default,,0000,0000,0000,,a carboxylic acid functional\Ngroup over here on the right.
Dialogue: 0,0:00:12.20,0:00:15.26,Default,,0000,0000,0000,,And this is the only chirality\Ncenter in lactic acid.
Dialogue: 0,0:00:15.26,0:00:17.53,Default,,0000,0000,0000,,It's an sp3 hybridized\Ncarbon with four
Dialogue: 0,0:00:17.53,0:00:19.40,Default,,0000,0000,0000,,different substituents\Nattached to it.
Dialogue: 0,0:00:19.40,0:00:20.89,Default,,0000,0000,0000,,So with only one\Nchirality center,
Dialogue: 0,0:00:20.89,0:00:23.69,Default,,0000,0000,0000,,we would expect to\Nhave two stereoisomers
Dialogue: 0,0:00:23.69,0:00:25.05,Default,,0000,0000,0000,,for this molecule.
Dialogue: 0,0:00:25.05,0:00:27.94,Default,,0000,0000,0000,,And those stereoisomers would\Nbe enantiomers of each other.
Dialogue: 0,0:00:27.94,0:00:30.47,Default,,0000,0000,0000,,Over here, I've picked\None of those enantiomers.
Dialogue: 0,0:00:30.47,0:00:32.42,Default,,0000,0000,0000,,And I've just drawn\Nit in this fashion.
Dialogue: 0,0:00:32.42,0:00:34.63,Default,,0000,0000,0000,,Let's see which enantiomer\Nwe have over here.
Dialogue: 0,0:00:34.63,0:00:36.78,Default,,0000,0000,0000,,Well, this is my\Nchirality center,
Dialogue: 0,0:00:36.78,0:00:38.44,Default,,0000,0000,0000,,the one attached to my OH.
Dialogue: 0,0:00:38.44,0:00:40.72,Default,,0000,0000,0000,,And if I were to assign\Nabsolute configuration
Dialogue: 0,0:00:40.72,0:00:43.40,Default,,0000,0000,0000,,to that chirality center,\NI look at the first atom
Dialogue: 0,0:00:43.40,0:00:45.06,Default,,0000,0000,0000,,connected to that\Nchirality center.
Dialogue: 0,0:00:45.06,0:00:47.59,Default,,0000,0000,0000,,Well, that's oxygen\Nversus carbon
Dialogue: 0,0:00:47.59,0:00:49.55,Default,,0000,0000,0000,,versus a carbon over\Nhere in my carbonyl.
Dialogue: 0,0:00:49.55,0:00:52.12,Default,,0000,0000,0000,,So obviously,\Noxygen's going to win.
Dialogue: 0,0:00:52.12,0:00:55.39,Default,,0000,0000,0000,,So we can assign oxygen\Na number 1 priority
Dialogue: 0,0:00:55.39,0:00:57.39,Default,,0000,0000,0000,,since it has the\Nhighest atomic number.
Dialogue: 0,0:00:57.39,0:01:01.18,Default,,0000,0000,0000,,And when I compare these\Ntwo carbons to each other,
Dialogue: 0,0:01:01.18,0:01:04.56,Default,,0000,0000,0000,,I know the carbon on the right\Nis double bonded to an oxygen.
Dialogue: 0,0:01:04.56,0:01:07.21,Default,,0000,0000,0000,,So that's going to give it\Nhigher priority than the carbon
Dialogue: 0,0:01:07.21,0:01:09.82,Default,,0000,0000,0000,,over here on the left since\Nthat's bonded to hydrogens.
Dialogue: 0,0:01:09.82,0:01:12.97,Default,,0000,0000,0000,,And then my other hydrogen\Nattached to my chirality center
Dialogue: 0,0:01:12.97,0:01:15.00,Default,,0000,0000,0000,,is going away from me in space.
Dialogue: 0,0:01:15.00,0:01:17.38,Default,,0000,0000,0000,,So when I'm assigning\Nabsolute configuration,
Dialogue: 0,0:01:17.38,0:01:19.93,Default,,0000,0000,0000,,I look at the fact that\Nit's going one, two, three.
Dialogue: 0,0:01:19.93,0:01:21.08,Default,,0000,0000,0000,,It's going around this way.
Dialogue: 0,0:01:21.08,0:01:22.47,Default,,0000,0000,0000,,It's going around clockwise.
Dialogue: 0,0:01:22.47,0:01:25.62,Default,,0000,0000,0000,,Therefore, this is the R\Nenantiomer of lactic acid.
Dialogue: 0,0:01:25.62,0:01:27.50,Default,,0000,0000,0000,,So that's all from\Na previous video.
Dialogue: 0,0:01:27.50,0:01:30.94,Default,,0000,0000,0000,,Now, if I want to draw a Fischer\Nprojection of R lactic acid,
Dialogue: 0,0:01:30.94,0:01:34.07,Default,,0000,0000,0000,,what I would do is I would\Nput my eye right here.
Dialogue: 0,0:01:34.07,0:01:36.78,Default,,0000,0000,0000,,And I would stare down\Nat my chirality center.
Dialogue: 0,0:01:36.78,0:01:39.99,Default,,0000,0000,0000,,
Dialogue: 0,0:01:39.99,0:01:42.74,Default,,0000,0000,0000,,And I would draw\Nexactly what I see.
Dialogue: 0,0:01:42.74,0:01:44.88,Default,,0000,0000,0000,,Well, if I'm staring\Ndown this way,
Dialogue: 0,0:01:44.88,0:01:47.25,Default,,0000,0000,0000,,I could draw a line\Nright here to represent
Dialogue: 0,0:01:47.25,0:01:49.39,Default,,0000,0000,0000,,my flat sheet of paper.
Dialogue: 0,0:01:49.39,0:01:52.76,Default,,0000,0000,0000,,And I can see that both\Nmy hydrogen and my OH
Dialogue: 0,0:01:52.76,0:01:56.20,Default,,0000,0000,0000,,are above my sheet of paper,\Nwhereas my carboxylic acid
Dialogue: 0,0:01:56.20,0:01:59.14,Default,,0000,0000,0000,,and my CH3 are below\Nmy sheet of paper.
Dialogue: 0,0:01:59.14,0:02:02.94,Default,,0000,0000,0000,,So this carbon is my\Nchirality center carbon.
Dialogue: 0,0:02:02.94,0:02:07.46,Default,,0000,0000,0000,,And I have my OH\Ncoming out at me.
Dialogue: 0,0:02:07.46,0:02:10.22,Default,,0000,0000,0000,,And this is actually going\Nto be on the right side.
Dialogue: 0,0:02:10.22,0:02:12.55,Default,,0000,0000,0000,,So if you take out your\Nmolecular model set,
Dialogue: 0,0:02:12.55,0:02:14.51,Default,,0000,0000,0000,,you will see this OH will\Nbe coming out at you.
Dialogue: 0,0:02:14.51,0:02:16.66,Default,,0000,0000,0000,,And it will be on the\Nright side of you.
Dialogue: 0,0:02:16.66,0:02:18.56,Default,,0000,0000,0000,,And this hydrogen will\Nbe coming out at you,
Dialogue: 0,0:02:18.56,0:02:20.19,Default,,0000,0000,0000,,and it will be on\Nthe left side of you.
Dialogue: 0,0:02:20.19,0:02:22.80,Default,,0000,0000,0000,,So that hydrogen would\Ngo over here like that.
Dialogue: 0,0:02:22.80,0:02:25.94,Default,,0000,0000,0000,,This carboxylic acid\Nfunctional group-- this
Dialogue: 0,0:02:25.94,0:02:27.58,Default,,0000,0000,0000,,is the top my head right here.
Dialogue: 0,0:02:27.58,0:02:30.61,Default,,0000,0000,0000,,Then that would make this go at\Nthe top of what I'm looking at.
Dialogue: 0,0:02:30.61,0:02:33.19,Default,,0000,0000,0000,,And so that is going\Naway from me in space.
Dialogue: 0,0:02:33.19,0:02:35.48,Default,,0000,0000,0000,,So we would use a dash\Nto represent that.
Dialogue: 0,0:02:35.48,0:02:39.53,Default,,0000,0000,0000,,And so we could go ahead and\Ndraw our C double bond to an O.
Dialogue: 0,0:02:39.53,0:02:41.70,Default,,0000,0000,0000,,And then an OH\Ngoing away from me.
Dialogue: 0,0:02:41.70,0:02:44.33,Default,,0000,0000,0000,,And then if I look at\Nthis CH3 group over here,
Dialogue: 0,0:02:44.33,0:02:45.54,Default,,0000,0000,0000,,it's also going away from me.
Dialogue: 0,0:02:45.54,0:02:46.77,Default,,0000,0000,0000,,It's going down in space.
Dialogue: 0,0:02:46.77,0:02:51.22,Default,,0000,0000,0000,,So I can represent it going\Ndown in space like that.
Dialogue: 0,0:02:51.22,0:02:54.16,Default,,0000,0000,0000,,And this is the viewpoint\Nof a Fischer projection.
Dialogue: 0,0:02:54.16,0:02:56.89,Default,,0000,0000,0000,,So if I'm going to convert\Nthis into a Fischer projection,
Dialogue: 0,0:02:56.89,0:03:00.68,Default,,0000,0000,0000,,a Fischer projection is just\Ndrawing a cross like that.
Dialogue: 0,0:03:00.68,0:03:03.06,Default,,0000,0000,0000,,And then at the top, you\Nhave your C double bonded
Dialogue: 0,0:03:03.06,0:03:05.07,Default,,0000,0000,0000,,to an O and then\Nan OH as just a way
Dialogue: 0,0:03:05.07,0:03:08.42,Default,,0000,0000,0000,,of abbreviating this carboxylic\Nacid functional group.
Dialogue: 0,0:03:08.42,0:03:10.24,Default,,0000,0000,0000,,And then I have a\Nhydrogen over here.
Dialogue: 0,0:03:10.24,0:03:12.51,Default,,0000,0000,0000,,And then I have an\NOH group over here.
Dialogue: 0,0:03:12.51,0:03:13.99,Default,,0000,0000,0000,,And then I have a CH3 here.
Dialogue: 0,0:03:13.99,0:03:16.28,Default,,0000,0000,0000,,So this is a Fischer projection.
Dialogue: 0,0:03:16.28,0:03:19.29,Default,,0000,0000,0000,,This is the Fischer\Nprojection for R lactic acid.
Dialogue: 0,0:03:19.29,0:03:21.13,Default,,0000,0000,0000,,So this is R lactic acid.
Dialogue: 0,0:03:21.13,0:03:24.04,Default,,0000,0000,0000,,And Fischer projections\Nwere invented
Dialogue: 0,0:03:24.04,0:03:27.97,Default,,0000,0000,0000,,by Emil Fischer, who won the\NNobel Prize in chemistry.
Dialogue: 0,0:03:27.97,0:03:30.30,Default,,0000,0000,0000,,One of the things was for his\Nresearch in carbohydrates.
Dialogue: 0,0:03:30.30,0:03:33.58,Default,,0000,0000,0000,,And he drew Fischer projections\Nto help him draw carbohydrates.
Dialogue: 0,0:03:33.58,0:03:35.87,Default,,0000,0000,0000,,And so that's where you'll\Nsee Fischer projections used
Dialogue: 0,0:03:35.87,0:03:37.95,Default,,0000,0000,0000,,most often, even though\Nsome chemists don't really
Dialogue: 0,0:03:37.95,0:03:38.87,Default,,0000,0000,0000,,like them very much.
Dialogue: 0,0:03:38.87,0:03:41.57,Default,,0000,0000,0000,,So this is the Fischer\Nprojection for R lactic acid.
Dialogue: 0,0:03:41.57,0:03:44.48,Default,,0000,0000,0000,,And if I wanted to draw the\NFischer projection for S
Dialogue: 0,0:03:44.48,0:03:47.36,Default,,0000,0000,0000,,lactic acid, I\Nwould just reflect
Dialogue: 0,0:03:47.36,0:03:49.50,Default,,0000,0000,0000,,this molecule in a mirror.
Dialogue: 0,0:03:49.50,0:03:52.84,Default,,0000,0000,0000,,So let's see if I can fit\Nmy mirror in over here.
Dialogue: 0,0:03:52.84,0:03:57.25,Default,,0000,0000,0000,,And I would have my OH\Nreflected in my mirror.
Dialogue: 0,0:03:57.25,0:04:00.66,Default,,0000,0000,0000,,And then I'd go ahead and\Ndraw my Fischer projection.
Dialogue: 0,0:04:00.66,0:04:03.17,Default,,0000,0000,0000,,And then my methyl group\Nwould be over here.
Dialogue: 0,0:04:03.17,0:04:04.95,Default,,0000,0000,0000,,My hydrogen would be over here.
Dialogue: 0,0:04:04.95,0:04:07.76,Default,,0000,0000,0000,,And my carboxylic\Nacid functional group
Dialogue: 0,0:04:07.76,0:04:08.72,Default,,0000,0000,0000,,would be right there.
Dialogue: 0,0:04:08.72,0:04:11.19,Default,,0000,0000,0000,,So this would be S lactic\Nacid on the right and R
Dialogue: 0,0:04:11.19,0:04:13.49,Default,,0000,0000,0000,,lactic acid on the left.
Dialogue: 0,0:04:13.49,0:04:16.58,Default,,0000,0000,0000,,S lactic acid is the\Ntype of lactic acid
Dialogue: 0,0:04:16.58,0:04:20.65,Default,,0000,0000,0000,,you find in the buildup of\Nmuscles after extreme exercise.
Dialogue: 0,0:04:20.65,0:04:22.88,Default,,0000,0000,0000,,And the type of lactic\Nacid that some people have
Dialogue: 0,0:04:22.88,0:04:26.80,Default,,0000,0000,0000,,heard of from milk is\Nactually a racemic mixture.
Dialogue: 0,0:04:26.80,0:04:30.78,Default,,0000,0000,0000,,So the bacteria in sour milk\Nwill break down the lactose
Dialogue: 0,0:04:30.78,0:04:36.01,Default,,0000,0000,0000,,into a 50% mixture of R and a\N50% mixture of S lactic acid.
Dialogue: 0,0:04:36.01,0:04:38.21,Default,,0000,0000,0000,,Let's take a look\Nat a carbohydrate,
Dialogue: 0,0:04:38.21,0:04:42.10,Default,,0000,0000,0000,,since Fischer used Fischer\Nprojections for carbohydrates,
Dialogue: 0,0:04:42.10,0:04:42.73,Default,,0000,0000,0000,,specifically.
Dialogue: 0,0:04:42.73,0:04:45.19,Default,,0000,0000,0000,,So here I have a carbohydrate.
Dialogue: 0,0:04:45.19,0:04:48.28,Default,,0000,0000,0000,,And if I were to number\Nthis carbohydrate,
Dialogue: 0,0:04:48.28,0:04:51.63,Default,,0000,0000,0000,,this carbonyl would\Nget a number 1.
Dialogue: 0,0:04:51.63,0:04:54.18,Default,,0000,0000,0000,,And then this would get\Na number 2 over here,
Dialogue: 0,0:04:54.18,0:04:56.36,Default,,0000,0000,0000,,a number 4, and a number 4.
Dialogue: 0,0:04:56.36,0:04:58.54,Default,,0000,0000,0000,,This is a four-carbon\Ncarbohydrate.
Dialogue: 0,0:04:58.54,0:05:01.83,Default,,0000,0000,0000,,How many stereoisomers does\Nthis carbohydrate have?
Dialogue: 0,0:05:01.83,0:05:06.11,Default,,0000,0000,0000,,Well, this carbon number\N2 is a chirality center.
Dialogue: 0,0:05:06.11,0:05:09.70,Default,,0000,0000,0000,,And carbon number 3\Nis a chirality center,
Dialogue: 0,0:05:09.70,0:05:11.69,Default,,0000,0000,0000,,so 2 chirality centers.
Dialogue: 0,0:05:11.69,0:05:14.36,Default,,0000,0000,0000,,So I use the formula\Nof 2 to the n,
Dialogue: 0,0:05:14.36,0:05:16.39,Default,,0000,0000,0000,,where n is the number\Nof chirality centers.
Dialogue: 0,0:05:16.39,0:05:21.25,Default,,0000,0000,0000,,So I would expect 2 squared,\Nor 4 possible stereoisomers
Dialogue: 0,0:05:21.25,0:05:22.14,Default,,0000,0000,0000,,for this molecule.
Dialogue: 0,0:05:22.14,0:05:24.12,Default,,0000,0000,0000,,So you could draw four\Ndifferent stereoisomers
Dialogue: 0,0:05:24.12,0:05:24.96,Default,,0000,0000,0000,,for this molecule.
Dialogue: 0,0:05:24.96,0:05:26.60,Default,,0000,0000,0000,,We'll draw them\Nin a few minutes.
Dialogue: 0,0:05:26.60,0:05:30.66,Default,,0000,0000,0000,,For right now, I've gone\Nahead and drawn one of them
Dialogue: 0,0:05:30.66,0:05:32.51,Default,,0000,0000,0000,,as a sawhorse projection.
Dialogue: 0,0:05:32.51,0:05:35.49,Default,,0000,0000,0000,,So here I have a sawhorse\Nprojection of one
Dialogue: 0,0:05:35.49,0:05:38.34,Default,,0000,0000,0000,,of the possible stereoisomers.
Dialogue: 0,0:05:38.34,0:05:40.22,Default,,0000,0000,0000,,And what we're\Ngoing to do is we're
Dialogue: 0,0:05:40.22,0:05:43.32,Default,,0000,0000,0000,,going to put our\Neye right up here.
Dialogue: 0,0:05:43.32,0:05:47.94,Default,,0000,0000,0000,,And we're going to stare\Nstraight down at this bond
Dialogue: 0,0:05:47.94,0:05:48.67,Default,,0000,0000,0000,,right here.
Dialogue: 0,0:05:48.67,0:05:50.79,Default,,0000,0000,0000,,And we're going to see if\Nwe can draw the Fischer
Dialogue: 0,0:05:50.79,0:05:52.35,Default,,0000,0000,0000,,projection for this molecule.
Dialogue: 0,0:05:52.35,0:05:54.50,Default,,0000,0000,0000,,So what do we see?
Dialogue: 0,0:05:54.50,0:05:58.62,Default,,0000,0000,0000,,Well, let's start with\Nthis carbon right up here.
Dialogue: 0,0:05:58.62,0:06:00.79,Default,,0000,0000,0000,,So we'll make that\Ncarbon this one.
Dialogue: 0,0:06:00.79,0:06:06.83,Default,,0000,0000,0000,,And you can see that the\NOH attached to that carbon
Dialogue: 0,0:06:06.83,0:06:07.92,Default,,0000,0000,0000,,is going to the right.
Dialogue: 0,0:06:07.92,0:06:10.00,Default,,0000,0000,0000,,And it's going up at us.
Dialogue: 0,0:06:10.00,0:06:14.08,Default,,0000,0000,0000,,So that OH is going to the\Nright, and it's going up at us.
Dialogue: 0,0:06:14.08,0:06:17.25,Default,,0000,0000,0000,,And then if I look at\Nthis hydrogen over here,
Dialogue: 0,0:06:17.25,0:06:17.96,Default,,0000,0000,0000,,it's on the left.
Dialogue: 0,0:06:17.96,0:06:19.59,Default,,0000,0000,0000,,And it's going up at us.
Dialogue: 0,0:06:19.59,0:06:24.10,Default,,0000,0000,0000,,So my hydrogen is on the\Nleft and it's going up at us.
Dialogue: 0,0:06:24.10,0:06:29.50,Default,,0000,0000,0000,,And this aldehyde functional\Ngroup, this CHO, you can see
Dialogue: 0,0:06:29.50,0:06:32.11,Default,,0000,0000,0000,,is going down.
Dialogue: 0,0:06:32.11,0:06:35.11,Default,,0000,0000,0000,,So this aldehyde functional\Ngroup is going away from us.
Dialogue: 0,0:06:35.11,0:06:37.17,Default,,0000,0000,0000,,So we can go ahead and\Nrepresent that aldehyde
Dialogue: 0,0:06:37.17,0:06:40.82,Default,,0000,0000,0000,,as going away from us\Nin space like that.
Dialogue: 0,0:06:40.82,0:06:44.08,Default,,0000,0000,0000,,Well, this chirality\Ncenter carbon
Dialogue: 0,0:06:44.08,0:06:47.28,Default,,0000,0000,0000,,is connected to this\Nchirality center carbon.
Dialogue: 0,0:06:47.28,0:06:49.10,Default,,0000,0000,0000,,So we'll go ahead and\Ndraw a straight line,
Dialogue: 0,0:06:49.10,0:06:50.87,Default,,0000,0000,0000,,since we're looking\Nstraight down at it.
Dialogue: 0,0:06:50.87,0:06:53.61,Default,,0000,0000,0000,,And once again, we will\Nfind that our OH group
Dialogue: 0,0:06:53.61,0:06:55.54,Default,,0000,0000,0000,,is on the right\Ncoming out at us.
Dialogue: 0,0:06:55.54,0:06:58.74,Default,,0000,0000,0000,,Our hydrogen is on the\Nleft coming out at us.
Dialogue: 0,0:06:58.74,0:07:00.70,Default,,0000,0000,0000,,So let's go ahead\Nand put those in.
Dialogue: 0,0:07:00.70,0:07:02.89,Default,,0000,0000,0000,,OH group is on the\Nright coming out at us.
Dialogue: 0,0:07:02.89,0:07:05.23,Default,,0000,0000,0000,,Hydrogen is on the\Nleft coming out at us.
Dialogue: 0,0:07:05.23,0:07:09.04,Default,,0000,0000,0000,,And then, of course, we\Nhave this CH2OH down here
Dialogue: 0,0:07:09.04,0:07:10.62,Default,,0000,0000,0000,,as going away from us in space.
Dialogue: 0,0:07:10.62,0:07:14.67,Default,,0000,0000,0000,,So we'll go ahead and\Ndraw that CH2OH going away
Dialogue: 0,0:07:14.67,0:07:15.86,Default,,0000,0000,0000,,from us in space like that.
Dialogue: 0,0:07:15.86,0:07:20.11,Default,,0000,0000,0000,,So that would be the Fischer\Nprojection translated.
Dialogue: 0,0:07:20.11,0:07:22.69,Default,,0000,0000,0000,,Let's go ahead and make it into\Nan actual Fischer projection
Dialogue: 0,0:07:22.69,0:07:25.73,Default,,0000,0000,0000,,where we just go ahead\Nand draw straight lines.
Dialogue: 0,0:07:25.73,0:07:27.79,Default,,0000,0000,0000,,And the intersection\Nof those straight lines
Dialogue: 0,0:07:27.79,0:07:31.66,Default,,0000,0000,0000,,are where our\Nchirality centers are.
Dialogue: 0,0:07:31.66,0:07:35.31,Default,,0000,0000,0000,,So this would be an H.\NThis would be an OH.
Dialogue: 0,0:07:35.31,0:07:36.14,Default,,0000,0000,0000,,This would be an H.
Dialogue: 0,0:07:36.14,0:07:37.25,Default,,0000,0000,0000,,This would be an OH.
Dialogue: 0,0:07:37.25,0:07:39.05,Default,,0000,0000,0000,,This would be our CH2OH.
Dialogue: 0,0:07:39.05,0:07:42.35,Default,,0000,0000,0000,,And then at the top, we\Nhave our aldehyde, CHO.
Dialogue: 0,0:07:42.35,0:07:45.89,Default,,0000,0000,0000,,So this is one of the four\Npossible stereoisomers.
Dialogue: 0,0:07:45.89,0:07:47.89,Default,,0000,0000,0000,,And Fischer projections\Njust make it much easier
Dialogue: 0,0:07:47.89,0:07:49.35,Default,,0000,0000,0000,,when we're working\Nwith carbohydrates.
Dialogue: 0,0:07:49.35,0:07:50.49,Default,,0000,0000,0000,,So this is one of the four.
Dialogue: 0,0:07:50.49,0:07:52.45,Default,,0000,0000,0000,,Let's go ahead and redraw\Nthe one we just drew
Dialogue: 0,0:07:52.45,0:07:55.70,Default,,0000,0000,0000,,and let's get the other three to\Nget our total of four on here.
Dialogue: 0,0:07:55.70,0:07:58.16,Default,,0000,0000,0000,,So I'm going to take the one\Nthat I just drew on the right.
Dialogue: 0,0:07:58.16,0:07:59.46,Default,,0000,0000,0000,,I'm going to redraw it.
Dialogue: 0,0:07:59.46,0:08:01.22,Default,,0000,0000,0000,,I'm going to draw it a little\Nbit smaller so everything
Dialogue: 0,0:08:01.22,0:08:02.06,Default,,0000,0000,0000,,will fit in here.
Dialogue: 0,0:08:02.06,0:08:06.03,Default,,0000,0000,0000,,So this is one\Npossible stereoisomer.
Dialogue: 0,0:08:06.03,0:08:08.91,Default,,0000,0000,0000,,I have my OHs on the right.
Dialogue: 0,0:08:08.91,0:08:10.90,Default,,0000,0000,0000,,I have my hydrogens.
Dialogue: 0,0:08:10.90,0:08:12.76,Default,,0000,0000,0000,,I have my CHO.
Dialogue: 0,0:08:12.76,0:08:13.46,Default,,0000,0000,0000,,I have my CH2OH.
Dialogue: 0,0:08:13.46,0:08:16.45,Default,,0000,0000,0000,,
Dialogue: 0,0:08:16.45,0:08:19.56,Default,,0000,0000,0000,,If I wanted to draw the\Nenantiomer to this molecule,
Dialogue: 0,0:08:19.56,0:08:22.76,Default,,0000,0000,0000,,I would just have to\Nreflect it in a mirror.
Dialogue: 0,0:08:22.76,0:08:24.15,Default,,0000,0000,0000,,So I could just do this.
Dialogue: 0,0:08:24.15,0:08:27.19,Default,,0000,0000,0000,,I could reflect the\Nmolecule in a mirror,
Dialogue: 0,0:08:27.19,0:08:29.73,Default,,0000,0000,0000,,and I would have the enantiomer.
Dialogue: 0,0:08:29.73,0:08:33.43,Default,,0000,0000,0000,,So this would be the\Nenantiomer to the stereoisomer
Dialogue: 0,0:08:33.43,0:08:35.47,Default,,0000,0000,0000,,that I just drew.
Dialogue: 0,0:08:35.47,0:08:38.29,Default,,0000,0000,0000,,If I wanted to\Ndraw the other two,
Dialogue: 0,0:08:38.29,0:08:39.79,Default,,0000,0000,0000,,I can just go ahead\Nand real quickly
Dialogue: 0,0:08:39.79,0:08:42.18,Default,,0000,0000,0000,,put in my Fischer\Nprojections right here.
Dialogue: 0,0:08:42.18,0:08:44.61,Default,,0000,0000,0000,,So I have two more to go.
Dialogue: 0,0:08:44.61,0:08:50.84,Default,,0000,0000,0000,,And I'm going to put the OH over\Nhere, and then the H over here,
Dialogue: 0,0:08:50.84,0:08:54.65,Default,,0000,0000,0000,,and then the OH over\Nhere, and the H over here.
Dialogue: 0,0:08:54.65,0:08:58.53,Default,,0000,0000,0000,,So this is yet another\Npossible stereoisomer.
Dialogue: 0,0:08:58.53,0:09:01.53,Default,,0000,0000,0000,,And I'll draw the mirror\Nimage over here on the right.
Dialogue: 0,0:09:01.53,0:09:04.23,Default,,0000,0000,0000,,So I have to have a\Nhydrogen right here.
Dialogue: 0,0:09:04.23,0:09:06.85,Default,,0000,0000,0000,,And then my OH must\Nbe on this side.
Dialogue: 0,0:09:06.85,0:09:11.42,Default,,0000,0000,0000,,And then I must have an\NOH right here, and then
Dialogue: 0,0:09:11.42,0:09:14.98,Default,,0000,0000,0000,,a hydrogen on the other side,\Nand then a CHO for my aldehyde,
Dialogue: 0,0:09:14.98,0:09:17.20,Default,,0000,0000,0000,,and a CH2OH.
Dialogue: 0,0:09:17.20,0:09:20.42,Default,,0000,0000,0000,,So here I have my four\Npossible stereoisomers
Dialogue: 0,0:09:20.42,0:09:22.79,Default,,0000,0000,0000,,for this carbohydrate.
Dialogue: 0,0:09:22.79,0:09:24.50,Default,,0000,0000,0000,,And I'm going to go\Nahead and label them.
Dialogue: 0,0:09:24.50,0:09:27.17,Default,,0000,0000,0000,,I'm going to label this\Nfirst one here stereoisomer
Dialogue: 0,0:09:27.17,0:09:31.76,Default,,0000,0000,0000,,A, stereoisomer B, stereoisomer\NC, and stereoisomer D.
Dialogue: 0,0:09:31.76,0:09:34.86,Default,,0000,0000,0000,,Well, C and D are mirror\Nimages of each other.
Dialogue: 0,0:09:34.86,0:09:37.17,Default,,0000,0000,0000,,So they are enantiomers\Nof each other.
Dialogue: 0,0:09:37.17,0:09:38.21,Default,,0000,0000,0000,,So these are enantiomers.
Dialogue: 0,0:09:38.21,0:09:40.82,Default,,0000,0000,0000,,A and B are mirror\Nimages, so they
Dialogue: 0,0:09:40.82,0:09:42.79,Default,,0000,0000,0000,,are enantiomers to each other.
Dialogue: 0,0:09:42.79,0:09:45.60,Default,,0000,0000,0000,,And then we talked about\Nin the diastereomer video,
Dialogue: 0,0:09:45.60,0:09:51.17,Default,,0000,0000,0000,,if I took one of the ones from A\Nand B-- so let me just go ahead
Dialogue: 0,0:09:51.17,0:09:53.03,Default,,0000,0000,0000,,and circle that--\Nif I just took A.
Dialogue: 0,0:09:53.03,0:09:55.78,Default,,0000,0000,0000,,If I took one of the ones from\NA and B and one of the ones
Dialogue: 0,0:09:55.78,0:09:58.00,Default,,0000,0000,0000,,from C and D, and\NI'll just take C. Then
Dialogue: 0,0:09:58.00,0:10:00.93,Default,,0000,0000,0000,,A and C are diastereomers\Nof each other.
Dialogue: 0,0:10:00.93,0:10:04.91,Default,,0000,0000,0000,,They are non-superimposable,\Nnon-mirror images
Dialogue: 0,0:10:04.91,0:10:05.57,Default,,0000,0000,0000,,of each other.
Dialogue: 0,0:10:05.57,0:10:07.75,Default,,0000,0000,0000,,So those are enantiomers\Nand diastereomers,
Dialogue: 0,0:10:07.75,0:10:11.35,Default,,0000,0000,0000,,to review what we covered\Nin an earlier video.
Dialogue: 0,0:10:11.35,0:10:13.39,Default,,0000,0000,0000,,Let's do one more thing\Nwith Fischer projections.
Dialogue: 0,0:10:13.39,0:10:16.27,Default,,0000,0000,0000,,Let's assign absolute\Nconfigurations
Dialogue: 0,0:10:16.27,0:10:18.86,Default,,0000,0000,0000,,to one of the stereoisomers.
Dialogue: 0,0:10:18.86,0:10:20.78,Default,,0000,0000,0000,,So let's just choose\Nthe first one, A.
Dialogue: 0,0:10:20.78,0:10:23.03,Default,,0000,0000,0000,,So we've been talking\Nabout A. And let's go ahead
Dialogue: 0,0:10:23.03,0:10:24.93,Default,,0000,0000,0000,,and redraw it really fast.
Dialogue: 0,0:10:24.93,0:10:29.41,Default,,0000,0000,0000,,And let's see how can we figure\Nout the absolute configuration
Dialogue: 0,0:10:29.41,0:10:34.36,Default,,0000,0000,0000,,at my chirality centers\Nfrom a Fischer projection.
Dialogue: 0,0:10:34.36,0:10:36.44,Default,,0000,0000,0000,,So it just makes a little\Nbit trickier than usual.
Dialogue: 0,0:10:36.44,0:10:38.33,Default,,0000,0000,0000,,So here I have my\NFischer projection.
Dialogue: 0,0:10:38.33,0:10:40.25,Default,,0000,0000,0000,,And your aldehyde's\Ngoing to get a 1,
Dialogue: 0,0:10:40.25,0:10:44.23,Default,,0000,0000,0000,,and then 2, 3, 4 in terms of\Nnumbering your carbon chain.
Dialogue: 0,0:10:44.23,0:10:46.19,Default,,0000,0000,0000,,I want to figure out the\Nabsolute configuration
Dialogue: 0,0:10:46.19,0:10:47.65,Default,,0000,0000,0000,,at carbon 2 here.
Dialogue: 0,0:10:47.65,0:10:49.93,Default,,0000,0000,0000,,So at carbon 2, what do I have?
Dialogue: 0,0:10:49.93,0:10:52.06,Default,,0000,0000,0000,,I know a Fischer\Nprojection tells me
Dialogue: 0,0:10:52.06,0:10:55.76,Default,,0000,0000,0000,,that if it's a horizontal line,\Neverything is coming out at me.
Dialogue: 0,0:10:55.76,0:10:57.43,Default,,0000,0000,0000,,So my OH is coming out at me.
Dialogue: 0,0:10:57.43,0:10:59.95,Default,,0000,0000,0000,,And my hydrogen is\Ncoming out at me.
Dialogue: 0,0:10:59.95,0:11:03.62,Default,,0000,0000,0000,,Let's go back up here and stare\Ndown that carbon 2 chirality
Dialogue: 0,0:11:03.62,0:11:04.12,Default,,0000,0000,0000,,center.
Dialogue: 0,0:11:04.12,0:11:06.76,Default,,0000,0000,0000,,And let's see what we would\Nactually see if we do that.
Dialogue: 0,0:11:06.76,0:11:09.39,Default,,0000,0000,0000,,So here is carbon 2 right here.
Dialogue: 0,0:11:09.39,0:11:12.64,Default,,0000,0000,0000,,I'm going to stare down\Nright here this time.
Dialogue: 0,0:11:12.64,0:11:15.07,Default,,0000,0000,0000,,So I have my OH\Ncoming out at me,
Dialogue: 0,0:11:15.07,0:11:17.24,Default,,0000,0000,0000,,my hydrogen coming out at me.
Dialogue: 0,0:11:17.24,0:11:19.28,Default,,0000,0000,0000,,That makes this\Nbond and this bond
Dialogue: 0,0:11:19.28,0:11:22.03,Default,,0000,0000,0000,,to actually go away\Nfrom me in space.
Dialogue: 0,0:11:22.03,0:11:24.05,Default,,0000,0000,0000,,So the aldehyde is\Ngoing to go away
Dialogue: 0,0:11:24.05,0:11:27.01,Default,,0000,0000,0000,,from me in space like that.
Dialogue: 0,0:11:27.01,0:11:29.63,Default,,0000,0000,0000,,So I'm going to go ahead\Nand draw my aldehyde.
Dialogue: 0,0:11:29.63,0:11:31.92,Default,,0000,0000,0000,,Now, I'm actually going to\Ngo ahead and show the carbon
Dialogue: 0,0:11:31.92,0:11:33.14,Default,,0000,0000,0000,,bond to one hydrogen.
Dialogue: 0,0:11:33.14,0:11:35.52,Default,,0000,0000,0000,,I know the carbon's double\Nbonded to an oxygen,
Dialogue: 0,0:11:35.52,0:11:36.81,Default,,0000,0000,0000,,so I'm going to go and do that.
Dialogue: 0,0:11:36.81,0:11:38.89,Default,,0000,0000,0000,,That was that trick we\Nlearned in an earlier video
Dialogue: 0,0:11:38.89,0:11:40.49,Default,,0000,0000,0000,,for assigning absolute\Nconfiguration.
Dialogue: 0,0:11:40.49,0:11:41.95,Default,,0000,0000,0000,,And then the rest\Nof the molecule's
Dialogue: 0,0:11:41.95,0:11:43.37,Default,,0000,0000,0000,,actually going down in space.
Dialogue: 0,0:11:43.37,0:11:46.29,Default,,0000,0000,0000,,So this would be a carbon\Nhere bonded to a hydrogen.
Dialogue: 0,0:11:46.29,0:11:48.95,Default,,0000,0000,0000,,And this carbon is bonded\Nto an oxygen and a carbon.
Dialogue: 0,0:11:48.95,0:11:50.69,Default,,0000,0000,0000,,So what is the\Nabsolute configuration
Dialogue: 0,0:11:50.69,0:11:51.72,Default,,0000,0000,0000,,of this carbon here?
Dialogue: 0,0:11:51.72,0:11:56.99,Default,,0000,0000,0000,,Well, if I think about this\Nis my chirality center,
Dialogue: 0,0:11:56.99,0:11:59.21,Default,,0000,0000,0000,,what are the atoms directly\Nattached to that carbon?
Dialogue: 0,0:11:59.21,0:12:01.69,Default,,0000,0000,0000,,Well, I have a hydrogen,\Na carbon, an oxygen,
Dialogue: 0,0:12:01.69,0:12:02.32,Default,,0000,0000,0000,,and a carbon.
Dialogue: 0,0:12:02.32,0:12:06.67,Default,,0000,0000,0000,,Well, immediately I know that\Nmy oxygen is going to win.
Dialogue: 0,0:12:06.67,0:12:09.98,Default,,0000,0000,0000,,So I can go ahead and assign\Na number 1 to my oxygen right
Dialogue: 0,0:12:09.98,0:12:10.65,Default,,0000,0000,0000,,here.
Dialogue: 0,0:12:10.65,0:12:13.07,Default,,0000,0000,0000,,And then I think about\Nwhat's next priority.
Dialogue: 0,0:12:13.07,0:12:15.80,Default,,0000,0000,0000,,Well, it would be\Ncarbon versus carbon.
Dialogue: 0,0:12:15.80,0:12:19.45,Default,,0000,0000,0000,,So at the top, I have\Noxygen, oxygen, hydrogen.
Dialogue: 0,0:12:19.45,0:12:22.41,Default,,0000,0000,0000,,The bottom carbon, I have\Noxygen, carbon, hydrogen.
Dialogue: 0,0:12:22.41,0:12:24.08,Default,,0000,0000,0000,,So we saw in an\Nearlier video, you
Dialogue: 0,0:12:24.08,0:12:25.46,Default,,0000,0000,0000,,go for first point\Nof difference.
Dialogue: 0,0:12:25.46,0:12:27.75,Default,,0000,0000,0000,,So oxygen versus\Noxygen, no one wins.
Dialogue: 0,0:12:27.75,0:12:30.28,Default,,0000,0000,0000,,Then I go oxygen versus\Ncarbon, and oxygen wins.
Dialogue: 0,0:12:30.28,0:12:32.16,Default,,0000,0000,0000,,So this would get\Na number 2 up here.
Dialogue: 0,0:12:32.16,0:12:34.43,Default,,0000,0000,0000,,And then this would get a\Nnumber 3 for my substituent.
Dialogue: 0,0:12:34.43,0:12:36.38,Default,,0000,0000,0000,,And my hydrogen\Nwould get a number 4.
Dialogue: 0,0:12:36.38,0:12:38.34,Default,,0000,0000,0000,,So I'm going around this way.
Dialogue: 0,0:12:38.34,0:12:42.50,Default,,0000,0000,0000,,I am going around this way,\Nif I ignore my hydrogen.
Dialogue: 0,0:12:42.50,0:12:44.46,Default,,0000,0000,0000,,So I'm going counterclockwise.
Dialogue: 0,0:12:44.46,0:12:48.40,Default,,0000,0000,0000,,So it looks like it's S.\NBut remember, the hydrogen
Dialogue: 0,0:12:48.40,0:12:50.07,Default,,0000,0000,0000,,is actually coming out at me.
Dialogue: 0,0:12:50.07,0:12:53.23,Default,,0000,0000,0000,,So in the little trick I showed\Nyou in the earlier video,
Dialogue: 0,0:12:53.23,0:12:55.52,Default,,0000,0000,0000,,if the hydrogen is coming\Nout at me, all you have to do
Dialogue: 0,0:12:55.52,0:12:56.56,Default,,0000,0000,0000,,is reverse it.
Dialogue: 0,0:12:56.56,0:13:00.00,Default,,0000,0000,0000,,So it looks like it's S, but\Nsince the hydrogen's coming out
Dialogue: 0,0:13:00.00,0:13:02.71,Default,,0000,0000,0000,,at, me, I can go ahead\Nand say with certainty
Dialogue: 0,0:13:02.71,0:13:05.56,Default,,0000,0000,0000,,that it is R at that\Nchirality center.
Dialogue: 0,0:13:05.56,0:13:09.73,Default,,0000,0000,0000,,So at carbon 2, at\Nthis carbon, it is R.
Dialogue: 0,0:13:09.73,0:13:13.19,Default,,0000,0000,0000,,So you can do the same thing\Nwith the chirality center
Dialogue: 0,0:13:13.19,0:13:14.54,Default,,0000,0000,0000,,at the third position.
Dialogue: 0,0:13:14.54,0:13:17.13,Default,,0000,0000,0000,,So you could do the same\Nthing with this one.
Dialogue: 0,0:13:17.13,0:13:20.38,Default,,0000,0000,0000,,And if you do that, you\Nwill find that it is also R.
Dialogue: 0,0:13:20.38,0:13:23.09,Default,,0000,0000,0000,,So you could go ahead and\Nsay for this carbohydrate,
Dialogue: 0,0:13:23.09,0:13:27.73,Default,,0000,0000,0000,,it is R at carbon 2,\Nand it is R at carbon 3.
Dialogue: 0,0:13:27.73,0:13:29.84,Default,,0000,0000,0000,,So it is 2R, 3R.
Dialogue: 0,0:13:29.84,0:13:32.14,Default,,0000,0000,0000,,And there's a 2R,\N3R stereoisomer.
Dialogue: 0,0:13:32.14,0:13:35.93,Default,,0000,0000,0000,,And you could do that for\Nall four of the stereoisomers
Dialogue: 0,0:13:35.93,0:13:37.75,Default,,0000,0000,0000,,that we drew for\Nthis carbohydrate.
Dialogue: 0,0:13:37.75,0:13:40.58,Default,,0000,0000,0000,,And you could then compare\Nenantiomers and diastereomers
Dialogue: 0,0:13:40.58,0:13:41.67,Default,,0000,0000,0000,,that way, as well.
Dialogue: 0,0:13:41.67,0:13:44.57,Default,,0000,0000,0000,,So that's a quick summary\Nof Fischer projections.
Dialogue: 0,0:13:44.57,0:13:45.20,Default,,0000,0000,0000,,Practice.
Dialogue: 0,0:13:45.20,0:13:47.93,Default,,0000,0000,0000,,And use your molecular\Nmodel set to help you
Dialogue: 0,0:13:47.93,0:13:50.53,Default,,0000,0000,0000,,with the visualization aspect.
Dialogue: 0,0:13:50.53,0:13:51.30,Default,,0000,0000,0000,,