Newman Projections - Free Educational videos for Students in K-12

Newman Projections - By The Organic Chemistry Tutor

Transcript


00:00	in this lesson , we're going to focus on drawing
00:03	Newman projections of certain molecules and we're going to discuss
00:08	the relative stability of those molecules . So let's go
00:11	ahead and start with Methane Ch three , Ch 3
00:16	. So how can we draw the newly projection along
00:18	the C1 C2 bond ? The first thing I would
00:21	like to do is expand this structure . So the
00:31	first carbon which will call c . one , it's
00:35	attached to three hydrogen atoms . So to draw the
00:41	newman projection draw circle And at the center this is
00:45	going to represent C1 which is in the front and
00:48	so it's attached to three hydrogen atoms now behind it
00:56	, which we can't see as carbon too , and
00:58	it's also Attached to three other hydrogen atoms . So
01:03	this is the staggered confirmation of ethane . Now ,
01:09	one thing we could do is rotate The C1C2 bond
01:13	such that this hydrogen is directly behind that one ,
01:17	so it's gonna be eclipse in it . So there's
01:20	two ways in which you can draw the human projection
01:24	of I think you can draw it like this .
01:27	So this is the staggered confirmation or you can draw
01:33	the eclipse confirmation . Which one do you think is
01:37	more stable ? The staggered confirmation ? Or the eclipse
01:42	confirmation . The hydrogen is in the back . I'm
01:45	going to try and read . You need to understand
01:55	that the staggered confirmation is more stable , then eclipsed
02:04	. And the reason for that is this interaction where
02:07	the hydrogen czar eclipse in each other , there's two
02:10	additional strength and so this confirmation is going to be
02:14	higher in energy . So this is the less stable
02:16	confirmation . And on the left we have the more
02:20	stable staggered confirmation . Now let's move on to our
02:27	next example . So let's draw the Newman projection of
02:31	butane along the C two , C three bond .
02:36	So first let's draw carbon too and carbon to be
02:40	now attached to carbon too , which is this carbon
02:44	right here , it has a method group on the
02:47	left And it's ACH two . So it has to
02:50	other hydrogen atoms attached to it . Now , carbon
02:55	three , which is this carbon , I'm going to
02:57	highlight that one in blue . It's also attached to
03:00	two hydrogen atoms and the method group . And so
03:05	we need to draw everything around This C two C
03:09	3 bond . So now let's draw a new projection
03:14	. I'm going to draw a smaller version this time
03:17	. So this is going to be carbon to which
03:19	I'm going to highlight in red this red dot .
03:22	So carbon two is in the front and carbon too
03:26	has a hydrogen , another hydrogen . And the method
03:29	group , I'm going to place the first method group
03:32	at the top And then the other two hydrogen Now
03:38	Carbon three , which is in the back . It
03:40	also has to hide regions And one Method Group .
03:44	So I'm going to place this method group at the
03:47	bottom and these hydrogen on this side . So this
03:52	is a staggered confirmation . But it has a specific
03:56	name called an anti confirmation . It is the most
04:00	stable of the four human projections of beating . The
04:04	reason for that is because the method groups are so
04:09	far apart , you want to keep them as far
04:11	apart as possible . And so this is the anti
04:14	confirmation of beauty . The diet federal angle between these
04:19	two method groups Is 180 . Now let's try the
04:25	other confirmations of beauty . So I'm going to keep
04:31	the first method group at the talk . I'm not
04:34	going to change the opposition . Now , the second
04:38	method group , we can put it right here and
04:41	so the other hydrogen will be around it . And
04:45	so as you can see we don't have the eclipse
04:47	confirmation yet . This is still another type of staggered
04:49	confirmation . However , this particular confirmation is known as
04:54	the guy ouch confirmation or the garage confirmation And a
05:00	diet federal angle between the two mafia groups is 60°.
05:06	. Now there is some steer extreme when the method
05:09	groups are close to each other And so whenever you
05:12	have this couch interaction , when it's 60° apart ,
05:16	you're gonna have this steering interaction . So therefore the
05:20	couch confirmation is less stable than the anti confirmation .
05:25	This is gonna be number one , meaning it's the
05:27	most stable , this is number two is the second
05:29	most stable . Now there's two types of eclipse confirmation
05:33	that we can draw the first one which I'm going
05:42	to show and red the hydrogen hydrogen eclipse the method
05:48	group and we have this method group eclipse in the
05:50	hydrogen . So this is the third most stable confirmation
05:59	and then in the least stable confirmation The two method
06:10	groups eclipse each other . Now think of the sun
06:16	or the moon eclipsing the sun , the moon could
06:19	completely block out the sun and that's what's happening here
06:23	. The white mother group is eclipsing the red metal
06:26	group . So technically you should not be able to
06:28	see the red metal group , it should be like
06:30	directly behind the white method group . So this is
06:35	called totally eclipse . It's the least stable of the
06:39	four confirmations of butane . Now let's go over the
06:43	angles for each one . So going back to the
06:47	gods confirmation , If you notice the angles between the
06:51	muscle groups is 60° or if you go in the
06:54	other direction It's 300 , so there's two angles that
06:58	corresponds to this confirmation 60 and 300 . Now for
07:07	The eclipse confirmation number three Notice that the methods are
07:12	120° apart . Or if you count in the other
07:15	direction there are 2 40 degrees apart . Because to
07:18	40 plus 1 20 Adds up to 360 . And
07:23	for the last one It's 0° apart 0° in 3
07:27	60 . They're the same . Now the reason why
07:30	I mentioned that is because when drawing the potential energy
07:33	diagram you can see how it relates to each other
07:59	. So this angle Is the 0° angle Here .
08:04	This is gonna be 60 and then 1 20 And
08:11	then this is 1 80 , 2 40 And then
08:18	300 And then back to 360 . So the anti
08:25	confirmation is the one with the lowest energy on the
08:29	Y axis . We have potential energy on the X
08:32	axis is the diet your angle so recall that the
08:36	anti confirmation which we said was the most stable .
08:39	It had a die . He'd roll angle of 180
08:41	and so it has the lowest energy . So this
08:44	was structure number one the most stable . The Second
08:48	One was number two and number two was the guardian
08:53	of action . And it had a die . He'd
08:55	roll angle of 60 and 300 which we saw on
09:00	the previous page . And then structure number three was
09:05	the eclipse confirmation . Which ? All right . E
09:08	for eclipsed and had two angles 1 22 40 which
09:13	we see here . And the instruction number four .
09:16	That was the least stable . So it has the
09:18	highest potential energy and it had a diet hydra angle
09:22	of zero . Established a total eclipse structure or totally
09:26	eclipsed rather And zero and 36 year the same .
09:30	So you could see where they're located on this potential
09:33	energy diagram . So as a potential energy increases the
09:38	stability of the molecule , decreases highly stable molecules .
09:44	Have low potential energy and unstable molecules have high potential
09:48	energy . So that's it for butane . Less shrub
09:53	in human projection of let's say 23 dimethyl , panting
10:02	, so feel free to pause the video and try
10:04	that and identify which of those Newman projections . This
10:09	could be many . Which one is the most stable
10:12	out of the ones you can draw . So first
10:15	let's draw a line structure . So here we have
10:17	plantain and then we have a method on carbon two
10:20	and three . And also I need to specify that
10:24	when he said draw the Newman projection along the C
10:26	two , C three bond . So this is Ch
10:32	tree . And then we have a CH and then
10:35	another CH . Three . And then it's a Ch
10:40	CH three , Ch two Ch stream . Mhm .
10:49	So this is carbon too . And this is carbon
10:53	dream . So carbon to has uh has to method
10:57	groups and it has a hydrogen . So here's the
11:07	first method group on carbon too . Here's the 2nd
11:11	1 . And then here is the hydrogen . Now
11:16	for carbon three , it too has a hydrogen a
11:20	method group , but it also has an ethyl group
11:24	. So let's put that in the back . So
11:27	here is the method group , here's the hydrogen and
11:33	here is the ethnic group . So what other Newman
11:40	projections can we draw of this molecule Of 2 ,
11:46	3 , dimethyl panting . So this is carbon one
11:51	. Carbon to has a method group . Carbon 3's
11:54	behind it , which also has a method group .
11:57	And then here's four and 5 . So we have
12:00	a total of seven carbon atoms . So let's redraw
12:11	this stuff around carbon to the two method groups with
12:15	the hydrogen . Now another staggered confirmation that we can
12:20	draw is we can put this ethnic group where this
12:24	method group is and so that's gonna give us Now
12:28	. Are these to stagger confirmations that I'm drawn right
12:32	now ? Or the the two that I have on
12:35	the board are these two the same ? Are they
12:37	different notice that they are equivalent to each other because
12:42	here we have a grouch interaction the same on this
12:45	side and there's another couch interaction between the method and
12:48	the method . So as you can see these two
12:51	structures are identical . However , we could create a
12:55	different structure if we place a method group here and
13:03	then the ethnic group here . So that's a different
13:10	staggered confirmation in our original structure . We had one
13:17	method method gouge interaction in the new structure . We
13:21	have to method method . Oh gosh interaction . And
13:26	in the old structure we had one methyl ethyl got
13:29	interaction . But in new structure we have Just one
13:33	methyl ethyl gadget of action . So in this new
13:35	structure we have a total of three got interactions in
13:38	the original one we have to . So this structure
13:42	here is less stable than this one . Now ,
13:45	let's see if we can draw another staggered newman projections
13:51	. Mm Because I think we can and we can
13:55	do so if we put the ethel between the two
13:58	methyl groups and let's put the method here . So
14:05	this time we only have one method method got interaction
14:10	. But now we have to method ethel's gouge interactions
14:15	. And because ethel is bulkier than method , it
14:19	stands to reason that an ethyl methyl gouging of action
14:22	has more energy than a method method gatun of action
14:26	. So therefore this is going to be number one
14:28	, the most stable Staggered confirmation that we can draw
14:32	. This is going to be number two , And
14:34	this is going to be number three the least stable
14:36	of all the staggered confirmations that we can draw based
14:40	on the idea that an ethyl methyl interaction has more
14:44	starik strain . Then a method method interaction . Now
14:52	let's draw the eclipse confirmations . Mhm . So let's
15:12	start With this part 1st and I'm going to begin
15:17	by eclipse in the method groups together . Let's make
15:36	this an ethnic group and then this is going to
15:40	be the other hydrogen . Mhm . Now let's try
15:46	the next structure . So here we have an H
15:55	. H . Eclipse interaction . So now let's put
15:59	a method group next to the hydrogen . So that's
16:02	gonna be different . Let's keep the ethnic group on
16:07	this side . If we put the ethnic group here
16:10	is the same as putting it here because the tomb
16:12	ethnic groups are the same . Now , the only
16:15	other different structure that we can draw is we can
16:19	put the ethyl group next to the hydrogen that will
16:31	be different than the first two . and then one
16:33	hydrogen has to be with one of the other method
16:37	groups . And the other method group has to be
16:38	there too . Now I'm going to leave it up
16:41	to you to rank the stability of these three eclipse
16:45	confirmations . But just to get you started , it's
16:48	good to know that whenever you have two hydrogen atoms
16:51	eclipse to each other , The original strain energy values
16:55	about four kg promote and when the hydrogen eclipses a
16:59	methyl group , It's about six kg promote whenever you
17:06	have two method groups , eclipse in each other ,
17:09	The energy value is 11 . So we have enough
17:12	information to compare these two molecules because these two interactions
17:18	between a method and the ethnic group did the same
17:21	. So we don't have to take that into account
17:23	. So for the two remaining groups , This has
17:27	a total energy profile of 12 . And for this
17:31	one it's 15 . Not taken the ethyl methyl interaction
17:36	into account . So because the structure on the right
17:39	has a higher potential energy value , we could say
17:42	it's less stable . Then the structure on the left
17:47	. So the structure on the left is going to
17:48	be more stable . Now I'll leave it up to
17:53	you to the research to determine how this molecule compares
17:57	to the other two . So you need to determine
18:01	the energy value between um ethel and the hydrogen .
18:06	I mean ethel and hydrogen and also ethel . And
18:09	a method in order to answer that question . Now
18:12	let's work on some practice . Two examples . Number
18:15	one draw the most stable confirmation of two method butane
18:20	along the C two , C three bonds . Feel
18:24	free to pause the video and try this example .
18:28	So let's start with the line structure . Have to
18:31	Metal beauty . So first we're gonna drop you teen
18:34	and then we have a method group on carbon too
18:40	. So this is carbon to and this is carbon
18:42	three . Now let's throw everything else that's attached to
18:46	those two carbons . So on carbon to . We
18:49	have another method group and is a hydrogen Keeping my
18:53	carbon can only form four bonds . Carbon three has
18:57	a method group attached to it , but it has
19:00	to hide students . So let's draw our first name
19:04	projection . So we're gonna have carbon to in front
19:09	. We have our first meta group and then we
19:13	have another method group to the left and then the
19:17	hydrogen . Mhm . So here are the three things
19:22	that we've added . So now to the back carbon
19:25	Or carbon three , we're gonna add these three groups
19:29	. So I'm going to start by putting the method
19:31	at the bottom and the other two hydrogen atoms here
19:35	. So notice that in this particular confirmation of two
19:39	method butane We only have one gouge interaction With an
19:44	energy profile of 3.8 kg promote . Mm . Now
19:50	let's try another one . Let's see what other new
19:53	projections that we can draw . So we can compare
19:57	it to our first example . Mhm . So the
20:00	first street groups , I'm gonna keep it the same
20:04	. Let's put this method group here . Yeah .
20:11	And then we can place the other two hydrogen atoms
20:16	. So notice that we have to go chain of
20:18	actions . So the energy profile for this particular confirmation
20:23	, it's going to be 3.8 plus 3.8 , Which
20:26	is 7.6 . Killing jews promote so far . We've
20:40	placed the mother group in this position and in this
20:43	one let's see what happens if we put it there
20:46	. Yeah . So if we put it towards the
20:49	right , the other hydrogen atoms have to go any
20:52	other position . So we only have one couch interaction
20:57	. In fact , these two confirmations are the same
21:01	. So those are all of the stable staggered confirmations
21:04	that we can draw . We know that the eclipse
21:07	confirmations will be less stable . So we're not going
21:09	to draw them . The one that is the most
21:11	stable is the one with the lowest potential energy .
21:15	So therefore this particular confirmation of two method . Butane
21:19	is the most stable . So this is our answer
21:23	number two . Consider the following confirmations of Butane .
21:27	What is the energy barrier between the totally eclipsed confirmation
21:32	and the anti confirmation of Butane . Now the energy
21:36	profile for the anti confirmation which is on the left
21:42	. Mhm . Is basically zero . We don't have
21:45	any gout interactions and there's no staggered or I mean
21:49	there's no eclipse interactions . So that's the energy profile
21:56	. Now on the right we have the totally eclipse
21:59	confirmation . So what's the energy profile for that ?
22:04	Based using the the table on the right , the
22:09	table on the right gives us the correspondent potential energy
22:11	for each grouping of action . So here we have
22:17	two ch trees that are eclipsed to each other .
22:21	So the energy value for that is 11 and then
22:26	we have two hydrogen atoms Better eclipse as well .
22:31	So the energy for each is four . So if
22:33	we add 11 plus four plus four , That's going
22:36	to be 19 . Yeah . So the difference between
22:44	these two energies , it's going to be the energy
22:47	barrier to rotation . So in order to rotate butane
22:55	from its anti confirmation two , it's totally eclipsed confirmation
23:00	. We need to put in 19 killer jewels of
23:03	energy per mole to get it going . So that
23:06	is the energy barrier to rotation to convert it from
23:09	anti to the total eclipse confirmation .

Summarizer

DESCRIPTION:

This organic chemistry video tutorial provides a basic introduction into newman projections. It explains how to draw the newman projections of ethane, butane, and 2,3-dimethylpentane. It explains how to draw the eclipsed and staggered conformations of ethane as well as the gauche and anti conformations of butane. It explains how to use conformational analysis to determine which conformation is most stable.

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