An Overview of Aldehydes and Ketones: Crash Course Organic Chemistry #27 - Free Educational videos for Students in K-12

An Overview of Aldehydes and Ketones: Crash Course Organic Chemistry #27 - By Math and Science

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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
00:08	Crash course Organic Chemistry you might know Aldo hides in
00:11	key tones for their strong , often sweet smells .
00:15	The key tone acetone , for example , is a
00:17	common ingredient in nail polish remover and we met the
00:20	fragrant Aldo hides vanilla and cinnamon to hide in episode
00:23	two . But these groups are also important in biochemistry
00:26	and drug treatments . There are key tone groups in
00:28	sex hormones like progesterone and testosterone . And then there's
00:31	cortisone and anti inflammatory medication or decks methods own a
00:35	steroid that's been used to treat arthritis , severe allergies
00:38	, Covid 19 and sometimes cancer . It's clear that
00:42	Aldo hides and ketones are important . So it's not
00:44	surprising that organic chemist spend so much time trying to
00:47	make them in more energy efficient and nonpolluting ways .
00:50	Let's get started . No , quite a bit of
01:03	this episode is going to summarize chemistry we've covered before
01:06	. But with more detail if you're diving in here
01:09	or even if it's just been a while since you
01:11	watch them , you may want to check out some
01:13	of these episodes . As a refresher , we're going
01:15	to be dealing with a lot of carbon Neil's a
01:17	carbon attached to an oxygen with the double bond .
01:20	Like this , the central carbon in this group is
01:22	called the carbondale carbon when it's at the end of
01:25	a chain attached to a carbon group and a hydrogen
01:28	, we're dealing with an alga hide . Or when
01:30	the carbon Neil carbon is attached to two carbon groups
01:33	, it's a ketone to name an alga hide .
01:35	You just take the standard name for the carbon chain
01:37	and pop an AL for Aldo hides . On the
01:39	end . For example , these Aldo hides are methanol
01:42	and ethanol , but these substances have been used by
01:44	chemists for ages . In fact , ethanol was first
01:48	discovered nearly 250 years ago . So they have these
01:51	old common names that you have to learn if you
01:53	want to talk the talk thankfully many of them are
01:56	straightforward and just end in al to hide like a
01:58	settled a hide and formaldehyde . Other Aldo hides go
02:01	by their aipac names . For example , Z Hex
02:04	three email smells of freshly cut grass and leaves and
02:07	is an attractant for lots of insects . And even
02:10	though four oxo , Pantanal has both a ketone and
02:12	an AL to hide , the alga high takes priority
02:15	in nomenclature and is designated position one . We count
02:18	along the carbon chain and stick on the prefix oxo
02:21	to indicate that the ketone is on carbon four ,
02:24	which brings us to key tones which all have own
02:27	on the end . So they're relatively easy to spot
02:29	. Some rely on Aipac names which are not as
02:32	fun to say . So we'll just put them on
02:34	the screen . That's video magic and others have common
02:37	names such as acetone and acid , a phenomenon now
02:40	that we've practiced naming Aldo hides and ketones . We
02:42	can get into making them . We've actually seen most
02:45	of these methods already , so they'll hopefully sound familiar
02:48	. For example , in episode 24 we learned that
02:50	primary alcohols can be oxidized to formaldehyde with a weaker
02:55	oxidizing agents such as peritoneum clara chromite . The reaction
02:58	stops at the Aldo hide using strong oxidizing agents like
03:02	chronic acid or even chromite salt is trickier though ,
03:05	even though the reaction goes through an alga hide intermediate
03:08	, powerful oxidizing agents can produce carb oxalic acids to
03:12	get key tones . You can oxidize secondary alcohols with
03:14	strong oxidizing agents like chromium six . We don't need
03:18	to be so careful picking our reactions with secondary alcohols
03:21	because they can only oxidized to the key tone .
03:23	These oxidation reactions are often heated . But if you've
03:27	ever forgotten about boiling water on the stove , you
03:29	may have come back to a pot with little or
03:31	no liquid in it , just like pasta won't soften
03:33	in a waterless pot . We can't let all the
03:35	liquid solvent evaporate from our reaction . Most reactions require
03:39	solvent and the reactions can even burn up if we
03:41	keep heating without solvent . This is where a technique
03:44	called reflex comes in which involves heating a chemical mixture
03:47	while cooling any evaporated solvent so that it condenses back
03:51	into the liquid . That way we don't lose anything
03:54	even after heating for a long time . No forgotten
03:57	stovetop accidents here , you can remember it like acid
03:59	reflux , that burning sensation when stomach acid bubbles up
04:02	towards your throat and then rejoins your digestive juices .
04:05	The thing is , even though chromium six is a
04:08	useful oxidizing agent , it's unpleasant stuff . Cancer ,
04:12	respiratory problems , kidney disease , you name it .
04:15	So we can use different oxidizing agents to make alva
04:17	hides and ketones . To one option is ozone 03
04:21	which is both higher yielding and kinder to the environment
04:24	. The reaction is called those analysis , which we
04:26	talked about in episode 17 with redox reactions . In
04:30	this reaction , we break the double bond of an
04:32	alkaline and form a carbon kneel on each side of
04:34	the carbons involved . For example , those analysis with
04:37	two metal to painting gives us both acetone and Prepon
04:40	. L If we start with a triple bonded AL
04:42	kind , we can also make our way to Aldo
04:44	hides and ketones . We have hydro operation , which
04:47	is anti Markov Makov edition in episode 18 we showed
04:51	BH 34 simplicity , but BH three doesn't actually exist
04:55	in that form . There are more common , even
04:58	bulkier reactions we can use to get really good anti
05:01	Mark kostikov selectivity like boring th f a cool double
05:05	ring structure called nine BBn and die same old boring
05:08	in Hyde reparation . We form the less substituted Enel
05:11	, thanks to the boring intermediate that forms from the
05:13	bulky Boren re agent . On the other hand ,
05:16	oxy mercure ation is more cognitive edition and gives us
05:19	the more substituted alcohol but we're not done yet .
05:22	The eagles that form from each of these reactions aren't
05:25	very stable and they exist in equilibrium with more stable
05:28	carbon Neil or keto forms . This balance ultimately gives
05:32	us Aldo hides or ketones from these reactions . We
05:35	covered this mechanism in a lot of detail in episode
05:38	18 . If you want to check back , there
05:40	are a few more options that we haven't learned yet
05:42	. But here's a quick preview . Acid chlorides can
05:45	react with organic copper compounds to give us ketones and
05:48	using special bulky reducing agents on Esther's can produce Aldo
05:52	hides . Now , part of why we care about
05:53	making alcohols and ketones is because chemists can do so
05:56	many things with them . The carbon oxygen double bonds
05:58	is polar , so we have a die poll .
06:01	In fact because the oxygen is so electro negative ,
06:04	we actually end up with bipolar residence where in one
06:07	form the oxygen atom has a negative charge while the
06:10	carbon Neil carbon has a positive one . All of
06:12	this means the carbon Neil carbon is a prime target
06:15	for nuclear filic attack , specifically in addition reactions .
06:18	Because there's no leaving group , we end up with
06:20	an sp three carbon and electrons pushed onto a negatively
06:23	charged oxygen , which will tend to pick up a
06:26	proton when we add some water at the end of
06:28	the reaction and form an O . H group .
06:30	A handy nuclear file we can add to . The
06:32	carbondale group is a cyanide salts CN minus . This
06:35	gives us a new functional group in the molecule that
06:37	we can turn into other things like a means in
06:40	carb oxalic acids . We'll get to know these reactions
06:43	much later in the series . Of course , if
06:45	you've read any agatha Christie , you might know that
06:48	sodium cyanide is one of the most rapidly acting poisons
06:50	. So double check your risk assessment for this one
06:53	. A less scary reaction from a health and safety
06:56	point of view is using an A satellite and I
06:58	am as our nuclear file , The satellite attacks the
07:01	carbonell carbon to ultimately form an alcohol with an AL
07:04	kind functional group , sometimes called a partial alcohol .
07:07	We can also choose hydride and ions as our nuclear
07:10	file . And yes , you heard me correctly ,
07:13	a neutral hydrogen atoms often loses its one electron to
07:16	become H plus , but it can also gain an
07:19	electron to have a pair and form h minus .
07:22	Examples of hydride reagents are sodium boron hydride and lithium
07:25	aluminum hydride . Let's look at the mechanism of this
07:28	reduction reaction . Using sodium boron . Hydride boron is
07:32	an electro positive atom with only three valence electrons .
07:35	It doesn't follow , the octet rule intends to form
07:38	neutral compounds with three covalin bonds , but it will
07:42	accept electrons into its empty p orbital informa borrow hydride
07:45	and ion bh four minus one of borrow hydrate and
07:48	ion attacks the carbon steel group in an alga hide
07:51	or ketone . Both the electrons in that fourth B
07:54	. H bond go with the hydrogen . So this
07:57	reaction results in neutral Bh three and an alcohol and
07:59	ion . This elk oxide can then react with the
08:02	water in the reaction to form an alcohol , specifically
08:05	a primary alcohol . If we had an alga hide
08:08	in a secondary alcohol , if we had a key
08:10	tone , notice the double bond in the molecule doesn't
08:13	react and the hydride and ion only attacks at the
08:16	electro positive carbonell carbon . And since alcohols and ketones
08:20	have tribunal plane or molecular geometry , the hydride can
08:23	attack one side or the other and we get a
08:26	receipt Mick mixture at a Cairo carbon one last re
08:29	agent that deserves a mention is the vinegary agent .
08:31	Take a fast phony um salad . It's named after
08:34	George Vidic who won the chemistry Nobel Prize for his
08:37	work in 1979 and village . And yes , that's
08:41	spelled Y L I D E because english is annoying
08:45	sometimes is a molecule with adjacent atoms that have opposite
08:48	formal charges , Specifically a negatively charged carbon iron attached
08:53	to an atom with a positive charge in the vinegary
08:55	agent . The positively charged atom is phosphorus in a
08:58	compound known as fostering . This is another example of
09:02	a resonant structure . So when we react in al
09:04	to hide or a ketone via the Vidic reaction ,
09:06	the mechanism begins when the nuclear Philip carbon ion of
09:09	the ill , it attacks the electro positive carbon ,
09:12	Neil carbon . Similar to these other reactions we've been
09:15	doing this makes a sweeter I on a molecule containing
09:18	atoms with positive and negative formal charges that are not
09:21	adjacent . So it's slightly different from an ill it
09:23	in this case the negatively charged oxygen of ours witter
09:27	ion quickly reacts with the positively charged phosphorus to form
09:31	a four member ID ring species called a 12 Aqsa
09:34	phosphate . Ain . The 12 in the name tells
09:37	us , the oxygen and phosphorus are next to each
09:39	other at the one and two positions of the four
09:42	member ID ring . The small ring , it's super
09:45	unstable while phosphorus oxygen double bonds are very stable .
09:48	So the Aqsa phosphate Ain collapses to form an alkaline
09:52	and try fennel phosphene oxide . This process is so
09:55	fast , we often represented as one step with two
09:58	arrows and by the way , this reaction only worked
10:01	with a primary IL ID . If we had to
10:04	ALC , you'll groups on the negatively charged carbon .
10:06	The reaction is too chunky and the reaction doesn't work
10:10	. The Vinick reaction is another carbon carbon bond making
10:12	reaction and chemists really love those specifically , we form
10:16	a Z alkaline as the major product and the reason
10:19	why is beyond the scope of this series . So
10:22	we won't get into it here if we can draw
10:24	resonant structures for the carbon ion in our Vidic re
10:27	agent we have a molecule called a stabilized village .
10:30	This re agent with different resonance structures has slightly lower
10:33	reactivity and gives us the alkaline . This mechanism is
10:36	beyond the scope of our course to . But basically
10:39	, since this reaction occurs more slowly , we have
10:41	time to form the more stable the alkaline as the
10:44	major product as opposed to hysterically crowded Z . Elkin
10:47	favored by the vinegary agent . So alcohols and ketones
10:50	are really useful for organic chemists and there's a lot
10:53	of information to keep straight . In this episode ,
10:55	we learned that Aldo hides and ketones contain carbon Neil
10:58	groups and the carbon um carbon is very susceptible to
11:01	nuclear filic attack . We can make them by oxidizing
11:04	alcohols . We can reduce them to form alcohols and
11:08	they allow us to extend the carbon chain by reactions
11:10	with eyelids . In the next episode , we'll look
11:13	at organic metallic chemistry , the chemistry of molecules with
11:16	carbon metal bonds . Until then , thanks for watching
11:18	this episode of Crash Course Organic Chemistry . If you
11:21	want to help keep all crash Course free for everybody
11:24	forever , you can join our community on Patreon .
11:30	Yeah .

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