The Basics of Organic Nomenclature: Crash Course Organic Chemistry #2 - Free Educational videos for Students in K-12

The Basics of Organic Nomenclature: Crash Course Organic Chemistry #2 - By CrashCourse

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00:0-1	You can review content from Crash course Organic Chemistry with
00:02	the crash course app available now for android and IOS
00:05	devices . Hi , I'm Debbie Chakravarty and welcome to
00:09	Crash course Organic Chemistry . Even when we speak the
00:12	same language , we have different ways to say the
00:14	same thing . Do you call a carbonated beverage a
00:17	pop soda or just coke Or maybe you're looking for
00:21	a drinking fountain and everyone keeps pointing you to a
00:24	bubbler . Other times we're not saying what we think
00:27	we mean . For example an american asking for chips
00:31	in the U . K . Isn't going to get
00:32	a bag of crispy potato circles . If they shout
00:35	out for their friend ken in japan , people might
00:38	wonder why they're yelling about a sword or if they're
00:41	trying to say they're embarrassed in peru with a fragmented
00:44	I'm embarrassed gotta they're actually saying they're pregnant . Language
00:47	is complicated and it can be especially confusing in the
00:51	chemistry lab if we ask our lab partner to pass
00:54	the dike laura , methane and they hand us a
00:56	bottle labeled methylene chloride . Is that the same chemical
00:59	or not ? To unite the scientific community ? The
01:02	International Union , A Pure and Applied Chemistry Otherwise known
01:06	as I you pack was established in 1919 . This
01:10	group wanted to make sure that chemists around the world
01:12	could communicate accurately . 100 years later , you pack
01:16	is still the guiding organization for all things nomenclature .
01:19	Thanks to them , we have some standard rules for
01:22	naming organic chemicals . Yeah . Mhm . Yeah .
01:35	By the time I you pack came along with standard
01:37	rules , Organic chemistry as a field was already over
01:40	100 years old . Many chemicals had common names given
01:43	to them by the people who discovered them based on
01:46	their source or smell or color . For instance ,
01:49	vanilla is isolated from vanilla , beans and cinema .
01:52	Aldo hide is isolated from cinnamon , alcohol , ether
01:56	, acetone and acetic acid or common names . To
01:59	while some common names might sound fun , you have
02:01	to memorize them and they don't tell you much .
02:04	Besides , like there's a chemical responsible for the flavor
02:07	and vanilla ice cream called vanilla not super useful for
02:10	learning chemical structures . Sometimes chemists even disagreed about what
02:14	each common name meant , sort of like regional differences
02:17	about what to call a carbonated beverage . Despite opec's
02:20	best attempts to make organic chemistry nomenclature less confusing .
02:24	Many common names are still used today , probably because
02:28	vanilla is easier to say and put on a bottle
02:30	than four hydroxy , three meth oxy Ben's Aldo high
02:33	. But that longer name is a systematic name that
02:36	follows a set of rules , which means anyone who
02:38	knows those rules can draw the structure . There are
02:41	three basic steps to aipac systematic naming will add more
02:45	as we discover more about organic molecules throughout the series
02:49	. But for now these will get us started .
02:51	Number one find the longest carbon chain and give it
02:54	a route name number to identify the highest priority functional
02:57	group and add it suffix to the root name and
03:00	number three identify the types of substitutes and their positions
03:03	on the carbon chain , then at a number of
03:05	prefix to the root name . So we start building
03:08	any systematic name with the root name , which comes
03:10	from the longest carbon chain . In the molecule ,
03:13	the word longest is key because some molecules will have
03:16	long chain sticking out that can throw you off ,
03:18	so make sure to do a little extra counting to
03:20	make sure you actually found the longest one . Carbon
03:23	chains containing up to four atoms have arbitrary sounding route
03:26	names . One carbon is meth too is F three
03:30	is prop and four butte . This can be a
03:33	little tricky to remember , but you can use this
03:35	pneumonic to help monkeys eat purple bananas for carbon chains
03:39	with 5 to 12 atoms . The root names are
03:41	similar to geometric shapes . For example , a pentagon
03:45	in geometry is a five sided ring and if a
03:47	carbon compound has the word pent as its root ,
03:50	then it's a five carbon chain , A six carbon
03:52	chain is hex , seven is helped , eight is
03:55	oct nine is nine , 10 is dec , 11
03:58	is on deck and 12 is dudek . If you
04:01	need a root name for a carbon chain with more
04:03	than 12 atoms , I don't have it memorized .
04:05	There are plenty of resources out there to look them
04:07	up . Chemists usually don't deal with longer chains and
04:10	there are plenty of other things to remember . Besides
04:12	what a 56 carbon chain is called back to her
04:15	. I you pack rules once we've counted are carbons
04:18	and have a root name . We need to add
04:20	a suffix to indicate what kind of organic molecules we're
04:22	dealing with . The simplest organic molecules are hydrocarbons ,
04:26	which only have hydrogen and carbon atoms . There are
04:28	four kinds of hydrocarbons , al canes , al keane's
04:32	al kinds and aromatics . But we'll only talk about
04:36	the first three for now because smelly aromatic compounds are
04:39	a little more complicated . Al canes only have single
04:42	bonds between carbons for these compounds , we take the
04:45	route name and tack on a suffix . For example
04:48	, this skeletal structure is a six carbon chain ,
04:50	so the root is hex and because there are only
04:53	single bonds , it's an al Kane and we add
04:56	the suffix aim , its hexagonal canes are kind of
04:58	boring compared to their hydrocarbon cousins . They're low energy
05:02	couch , potatoes and don't interact with many other compounds
05:05	. On the other hand , Calkins and all kinds
05:07	have functional groups . Remember last episode we said that
05:10	functional groups are where all the cool chemistry happens in
05:13	al keen's the functional groups are double bonds between carbons
05:16	and in all kinds the functional groups are triple bonds
05:19	between carbon Calkins and all kinds can do fun reactions
05:23	to make things like light emitting polymers , which are
05:25	big molecules with regions where electrons move around on a
05:29	race track that absorbs energy and amidst light . But
05:32	I'm getting ahead of myself to name an alkaline ,
05:34	we find the longest chain of carbon atoms and it
05:37	must include a double bond . If the longest carbon
05:40	chain doesn't include a double bond , it's not named
05:42	as an alkaline . Sorry , I don't make the
05:44	rules . I you pack does . Since I You
05:46	peck rules are all about communication . We want to
05:49	let people know where that double bond is on the
05:51	chain . So well number the carbon starting on the
05:53	end closest to the double bond . For the sake
05:56	of consistency . We want to keep the numbers as
05:58	low as possible , then we'll take the lowest number
06:00	touching the double bond , combine it with the suffix
06:03	in and add that to the root name of our
06:05	change . For example , the longest chain in this
06:07	molecule is a five carbon chain , so the root
06:10	is pent because there's a double bond , we know
06:13	the suffixes in . But we also have to number
06:16	the carbon starting from the end closest to the double
06:19	bond , that's 12345 And because the double bond is
06:23	between carbons one and to this compound is pent one
06:26	. E notice the punctuation here . We stick dashes
06:29	around the number to name all kinds the hydrocarbons .
06:31	With a triple bond . We do the same thing
06:34	first we find the longest chain of carbon atoms and
06:36	pick a route name . Then we number the chain
06:38	from the end closest to the triple bond to let
06:41	people know where it is and tack on the Suffolk
06:43	. I for example an eight carbon chain with the
06:46	triple bond in the center would be called opt for
06:48	to finish the aipac rules . Once we have a
06:51	root name and suffix , we might be done if
06:53	the molecule doesn't have anything fancy going on . But
06:55	frequently organic molecules have substitue ints we're playing old hydrogen
07:00	is on a carbon chain can be replaced by other
07:03	carbon chains or halogen atoms like chlorine , bromine and
07:07	iodine . For example , we communicate where substitutes are
07:10	by adding prefixes before the root name plus . Just
07:13	like we had to count carbons for al keens and
07:15	al kinds . We need to communicate where every substitution
07:19	has done its substitute . If we're dealing with an
07:21	al caine where the longest carbon chain only has single
07:24	bonds will number the chain so that the carbon atoms
07:26	with a substitute . Rinse get the lowest numbers .
07:29	For example , let's take our hexen from before and
07:31	replace one hydrogen on a carbon with the CH three
07:34	groups . So in this case we have an al
07:36	Kane and we want to number the longest six carbon
07:39	chain so that the carbon with the substitution is to
07:42	not five . Remember we want to keep the numbers
07:45	as low as possible . The ch three group takes
07:47	the same name as a one carbon chain route meth
07:50	and because this group is a substitute it gets a
07:53	new ending spelled Y . L . So the prefix
07:56	we add is to metal to communicate where and what
07:59	it is and this compound is to metal hexen .
08:02	If the molecule is flipped over we could start from
08:04	the left and it would still be two metal hexen
08:07	. They're the same compound . No matter if the
08:08	metal is drawn on the right or the left ,
08:11	if we have two or more of the same substitutes
08:13	we had di tri tetra and so on to the
08:17	prefix . So if we took two metal hexen and
08:19	added another ch three group to a different carbon we
08:23	get to four die metal hexen notice the punctuation here
08:26	to the numbers are separated from each other by a
08:29	comma and are separated from the words by a dash
08:32	. But there are other substitutes besides carbon chains .
08:35	Let's say we take our 24 dimethyl hexen and replace
08:38	a hydrogen atom on carbon three with the halogen like
08:42	a chlorine atom . So the molecule name gets another
08:45	prefix . Colleges get the N . In their name
08:48	replaced with the letter O . So chlorine becomes claro
08:51	bro , mean becomes promo and iodine becomes IOD .
08:55	Oh that means we need to attack on the prefix
08:57	three claro here . Lastly when we add substitution prefixes
09:01	, Aipac rules say we need to put them in
09:03	alphabetical order and the multipliers , di tri and tetra
09:07	do not count when we're alphabetize ng . So this
09:10	molecule is named three claro to four dimethyl hexen .
09:14	These rules about substitution prefixes are mostly the same for
09:17	all kinds and all kinds except when it comes to
09:20	numbering the chains . The double and triple bonds between
09:22	carbon atoms have priority over substitution sticking out . So
09:26	we start numbering the chain closest to the bonds instead
09:29	of the substitution . If we take our alkaline friend
09:31	pent one en and add an ethyl group that's two
09:34	carbons in six hydrogen that carbon three . We named
09:38	this three ethyl pent one . Or if we put
09:40	two methyl groups on the 2nd and 7th carbons of
09:43	the alkaline opt for ein meet the spectacular to seven
09:47	die metal oCT four . Now that we have the
09:50	basics , we can start naming any compound even if
09:53	they look kind of complicated with more than one functional
09:55	group and substitute went like this molecule . But we
09:58	got this . Don't worry . We have our trusty
10:01	steps number one , find the longest carbon chain and
10:04	give it a route name . In this case we
10:05	see there's a seven carbon chain here . So the
10:08	root is hep number to identify the highest priority functional
10:12	group and added suffix to the root name . Al
10:15	keens and all kinds have equal priority when it comes
10:17	to numbering . But when an alkaline and alkaline tie
10:20	for the lowest number , the al keen winds will
10:23	count from both ends to see what's up and look
10:25	because the alkaline and alkaline tie for the lowest number
10:28	, the alkaline winds . So we'll use the numbering
10:31	where the double bond is lower . Now we have
10:33	to name our double and triple bond functional groups and
10:36	the alphabetical order rule still applies here . So with
10:39	the root and Suffolk's combined , we have helped one
10:41	in six . I finally number three , identify the
10:44	types of substitue ints and add a number of prefix
10:47	to the root me in this case there's a bombing
10:49	on carbon four and a methyl group on carbon three
10:53	taking alphabetical order into account . We add four bromo
10:56	three metal before the route and Suffolk's and we've conquered
10:59	this puzzle . It's four bromo three metal help one
11:02	in six . I it's kind of a mouthful to
11:05	say but so much more useful to chemists and if
11:07	I named it the bulky in or something . Now
11:10	remember that conundrum from the beginning when we asked our
11:12	lab partner for declare a methane and got a bottle
11:16	of methylene chloride . Let's build those molecules . Looking
11:19	at the name Die Clara methane . We know from
11:21	meth that this is a single carbon and and that
11:24	it's an al cane with single bonds . The dike
11:27	laura tells us that we have to chlorine atoms connected
11:30	to the only carbon no substitute number required . That's
11:33	the skeletal structure . And if we want to get
11:35	all fancy with a lewiS structure , we know that
11:37	carbon often makes four bonds so we can add two
11:40	hydrogen atoms to finish it off . methylene chloride is
11:43	trickier because we can't use our Aipac rules . We
11:46	just need to know that methylene is a common name
11:49	for a CH two groups . Then because chloride is
11:51	in the name , we can get to the final
11:53	structure by filling in the two open spots with chlorine
11:56	. The end structure is the same . So our
11:58	lab partner didn't know what they were doing . But
12:00	calling this compound dyke laura methane makes it easier for
12:04	scientists to know they're talking about the same thing .
12:06	In this episode , we learned that there are three
12:09	steps to naming molecules which include the root name ,
12:12	a suffix based on functional groups and a prefix based
12:15	on substitutes . And we number the longest carbon chain
12:18	by giving the highest priority functional group , the lowest
12:21	possible number or whatever gives substitue ints the lowest possible
12:25	numbers . Next time we'll learn how to give molecule
12:28	systematic names when they have functional groups with hetero atoms
12:31	. Thanks for watching this episode . Of Crash course
12:33	Organic Chemistry . If you want to help keep all
12:36	crash course free for everybody forever , you can join
12:40	our community on patreon

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