Aldehyde and Ketone Reactions - Hydrates, Acetals, & Imines: Crash Course Organic Chemistry #29 - Free Educational videos for Students in K-12 | Lumos Learning

Aldehyde and Ketone Reactions - Hydrates, Acetals, & Imines: Crash Course Organic Chemistry #29 - Free Educational videos for Students in k-12


Aldehyde and Ketone Reactions - Hydrates, Acetals, & Imines: Crash Course Organic Chemistry #29 - By CrashCourse



Transcript
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 dave okay Chakravarty and welcome
00:08 to Crash Course Organic Chemistry back in episode 27 we
00:12 talked a lot about the synthesis of Aldo hides and
00:14 key tones and now that we know the basics ,
00:16 we can build up to some more familiar chemical reactions
00:19 involving the carbon Neil group , a carbon attached to
00:22 an oxygen with a double bond stick with me for
00:24 a second . I'm a huge fan of reality tv
00:27 . I can't stop watching everything in the bravo cinematic
00:30 universe and a common character . Trope though , it's
00:33 definitely unhealthy and we should probably question why it's become
00:36 so normalized is the overstressed mom who takes anti anxiety
00:40 pills to make it through the day . The stereotype
00:43 has been around since the 19 sixties and was even
00:45 immortalized in the Rolling Stone song Mother's Little Helper .
00:48 It's complicated because sedatives like Xanax or Valium can be
00:52 prescribed as anti anxiety medication and really help people ,
00:56 but they have also been abused because our focus here
01:00 is organic chemistry . In this episode , we'll learn
01:02 what these sedatives all have in common . Carbonell chemistry
01:08 . Mhm mm . Thanks to the polar ceo bond
01:18 in a carbon steel group , the carbondale carbon has
01:21 a partially positive charge . In episode 27 we talked
01:24 about cyanide , a satellite and ions and the fast
01:27 ammonium eyelids used in the video reaction attacking this partially
01:31 positive carbon . These reactions extend the carbon chain allowing
01:35 us to make bigger , more complicated molecules . And
01:38 other nuclear files can also attack the carbon Neil group
01:41 . In this episode will focus on addition reactions of
01:44 oxygen and nitrogen based nuclear files . A simple oxygen
01:48 based nuclear file that were already quite familiar with is
01:50 water . If you mix water with an alga hide
01:52 or ketone and equilibrium forms with the hydrate form called
01:56 general dials or gem dials . The word germinal is
01:59 similar to gemini's , one of several latin words describing
02:02 twins . And in chemistry , germinal is used when
02:05 we're talking about a molecule with two or more of
02:08 the same functional group attached to a single atom .
02:11 Usually this equilibrium favors the alga hide or ketone because
02:14 of inductive effects groups like metals or ethel's are electron
02:18 releasing , meaning they push electrons towards the partially positive
02:22 carbon and carbon Neil and stabilize it . There are
02:25 examples that break this pattern though like the smallest Aldo
02:28 hide formaldehyde , mixing water with formaldehyde produces a solution
02:32 called formalin formal and helped preserve tissues from decay .
02:36 So it's what scientists use to preserve tissue specimens in
02:39 jars and not just scientists artists to Damien Hirst exhibited
02:44 a whole preserve tiger shark . Thinking about inductive effects
02:47 . The hydrogen atoms on formaldehyde don't do much to
02:50 stabilize the partial positive charge on the carbon . So
02:54 the equilibrium in a formal in solution very much favors
02:57 the gem dial , not the alga hide . We
02:59 can also make stable gem dials by substituting Aldo hides
03:02 with strong electron withdrawing groups like chlorine , which destabilized
03:06 the partial positive charge on the carbondale carbon . For
03:09 example , if we mix to to to try clara
03:12 a settled to hide with water , it forms chloral
03:15 hydrate , which was given as a sedative in asylums
03:17 and much abused in the late 19th century chloral hydrate
03:21 in ethanol is colloquially known as knockout drops or a
03:24 mickey finn , which is probably named after a Chicago
03:27 bartender who gained infamy after using this mixture to incapacitate
03:32 and steal from some of his customers . Big yikes
03:35 . Now we can also react carbonell compounds with other
03:38 oxygen based nuclear files like alcohol groups . When a
03:41 single alcohol group adds to an AL to hide ,
03:44 we get a heavy a settle . The name comes
03:46 from the greek word hemi , meaning half because only
03:49 one alcohol is added . There are also full blown
03:52 as tools that we'll talk about in a bit which
03:54 have two alcohol groups added . Hermia settles are generally
03:57 less stable than their Aldo hide equivalents . So the
04:00 equilibrium favors the alga hide as it does with many
04:03 gem dials , sugars and other molecules that can form
04:06 inter molecular and sick leukemia settles can be exceptions .
04:10 In a quick solution , glucose rapidly inter converts between
04:14 its straight chain and cyclic forms when one of its
04:16 alcohol groups attacks it's carbondale carbon . Since the carbondale
04:20 group in glucose has a traditional planner geometry and our
04:23 intra molecular hydroxy nuclear file can attack from either side
04:27 are hemi . A subtle products are to die hysteria
04:30 MERS , but we can get even more specific in
04:33 what we call them . The sugar world actually has
04:35 lots of special vocabulary . The hemi , a subtle
04:38 carbon of a sugar is called the an americ carbon
04:40 . So these two products are more precisely called an
04:43 Immers , one labeled alpha and one labeled beta .
04:46 In the beta animal , these groups end up on
04:48 the same side and in the alpha animal , these
04:50 groups are opposite . The beta animal of glucose is
04:53 actually favored in water because similar to cycle heck saying
04:57 it can adopt a comfy , stable chair confirmation .
05:00 And all the groups are equatorial , which also helps
05:03 reduce derek hindrance and increased stability that covers the basics
05:07 of hermia settles . So now let's take off that
05:09 heavy prefects and make a settles which form when two
05:12 alcohol groups add to an AL to hide or a
05:15 key tone . These reactions are acid catalyst . So
05:18 the three players are a carbon steel group in alcohol
05:21 and acid . Looking at the summary reaction , we
05:23 can see that we need to add two molecules of
05:25 methanol to the carbonell carbon to form the product .
05:29 So let's puzzle through the mechanism . If we added
05:31 methanol as a first step , that would give us
05:34 a negative charge , which we can't have in an
05:36 acid . Okay , so we've got to try something
05:39 else to start in acidic conditions . We have protons
05:42 and there's a lone pair on the carbon oxygen .
05:45 So what if that loan paragraph two proton from an
05:48 ox ammonium ion ? We have a positive charge ,
05:51 which is totally fine in our acid . Even though
05:54 this works as a first step , the oxygen isn't
05:56 happy about this whole positive charge situation . It draws
06:00 a pair of electrons in the carbon oxygen double bonds
06:03 towards itself , making the carbondale carbon very electra positive
06:06 and prone to nuclear filic attack . Looking at our
06:09 product , we want to add meth oxy groups to
06:11 that carbon . So that means the nuclear file we
06:14 choose for this attack is our alcohol . Specifically a
06:16 lone pair on the oxygen of one of the alcohol
06:19 molecules attacks the carbon carbon and adds a methanol .
06:23 We've still got a positive charge on the molecule though
06:25 , so this isn't stable enough to be an end
06:27 product . We've got to make our way to a
06:29 neutral molecules somehow . Remember , we've got plenty of
06:32 alcohol molecules floating around with two lone pairs on their
06:35 oxygen atoms . So one of those alcohols can grab
06:38 the spare proton on our molecule , leaving us with
06:40 an O . H . And an O . R
06:42 . Group attached to the what was the carbon Neil
06:44 carbon ? Now we have a hemi a subtle ,
06:46 so we're getting closer but to have a full blown
06:50 a subtle we need another myth oxi group . Instead
06:52 of that . Ohh . In our acidic conditions ,
06:54 we can get rid of the O . H .
06:56 By making it a good leaving group that ohh grabs
06:58 a proton from a pro donated molecule of methanol .
07:01 We might be tempted to have another molecule of methanol
07:04 attack and kick off water at this point , but
07:06 that would be like S and two at a tertiary
07:08 carbon , which doesn't work because remember there's not enough
07:12 room for the backside attack . Instead , we get
07:15 a little help from the adjacent oxygen . A lone
07:18 pair of electrons on the oxygen of the newly attached
07:21 alcohol group help push out water , forming an arc
07:24 sodium ion and a molecule that's not that different from
07:27 where we started except now , instead of a protein
07:30 ated carbondale , we have a carbon feel attached to
07:32 a metal group on oxygen . The similarity is important
07:35 to notice because we can basically do the same set
07:38 of moves again . A nuclear filic attack from another
07:41 alcohol molecule followed by D pronation . And we get
07:44 our a settle with two meth oxy groups . We're
07:46 done . That was a lot . So let's review
07:49 all of the steps of our reaction mechanism with the
07:51 arrow pushing in these acidic conditions . This process is
07:55 reversible heat and to settle with water and acid and
07:58 boom back to the ketone or Aldo hide . But
08:02 if acid isn't present a settles are really stable once
08:05 they're formed , in fact , they won't even react
08:08 with really strong nuclear files like carbon ions . Societal
08:10 formation is an important strategy for controlling the reactivity of
08:14 Aldo hides in ketones in multi step reactions . So
08:18 we'll come back to this when we talk about protecting
08:20 groups in a later episode , for now , we'll
08:22 move on to another similar reaction involving the formations of
08:26 means in china means it means our molecules with carbon
08:29 nitrogen double bonds and china means contain a carbon carbon
08:32 double bond next to an amine and al keen .
08:35 Plus in a mean , it means come from a
08:37 carbon Neil and a primary amine , while china means
08:41 come from secondary amines . One way to remember .
08:43 The difference is to notice that the words mean and
08:46 a mean are the same except for one letter .
08:49 So it means come from primary amines . Inamine ,
08:52 on the other hand , has two extra letters .
08:55 So china means come from secondary amines . The mechanism
08:58 for women formation is similar to a subtle formation with
09:02 three main players . A carbon you'll group a primary
09:05 amine an acidic conditions . Once again , there's a
09:08 lone pair on the carbon . He'll oxygen that can
09:10 grab a proton . Then the nuclear file , which
09:13 is the nitrogen . In the I mean this time
09:15 can attack the carbon atom of the protein ated carbonell
09:18 group . The pi electrons in the carbon oxygen double
09:20 bond neutralized the axe , ammonium ion and our intermediate
09:23 molecule has an amine and an O . H .
09:26 On the What was the carbonell carbon ? As in
09:28 a subtle formation , oxygen gets protein ated the nitrogen
09:32 lone pair forms a carbon nitrogen double bond and water
09:35 is eliminated . That leaves us with an a mini
09:37 um ion , which is any molecule with a positive
09:40 charge on the double bond in nitrogen . After a
09:43 deep pronation , we get an amine . However ,
09:46 if we're making an Inamine and start with a carbon
09:48 steel group , a secondary amine and a set of
09:50 conditions , we can't do this final discrimination step .
09:54 The nitrogen has to our groups . Instead of a
09:56 hydrogen , we can just kick out . So instead
09:59 the final step of the mechanism is deep resonating the
10:01 carbon adjacent to our mini um ion giving us an
10:04 enemy . I mean this is a great moment to
10:06 mention a compound called nine hydrant , which is used
10:09 in chromatography to identify amino acids and forensics , to
10:12 view fingerprints specifically nin hydrant detects the amines present in
10:16 the amino acids and proteins left behind by our fingerprints
10:20 . When it reacts with the amino acids , a
10:22 deep blue purple color appears called romans purple . This
10:26 is actually an immune forming reaction that occurs on the
10:29 keto form of nine hydrant . And the mechanism is
10:33 fairly straightforward that central carbonell carbon in the five member
10:37 ID ring , smushed between all those carbonell groups has
10:39 a big partially positive charge . So it's really attractive
10:44 to nuclear files as a result , when Inamine turns
10:46 up , say from the oily residue left by a
10:49 finger , the lone pair on the nitrogen attacks the
10:52 central carbon . Then the nine hydrant is dehydrated and
10:55 we form an enemy in the next few steps of
10:58 this mechanism are beyond the scope of this episode .
11:00 But basically another molecule of nine hydrogen reacts and the
11:04 two molecules link up through the nitrogen atom . This
11:07 compound is responsible for that pretty purple color and successful
11:11 fingerprints sleuthing to continue linking our carbonell chemistry to real
11:14 world applications . We can also look at the anti
11:16 anxiety medicine that stereotype of dramatic tv . We talked
11:21 about Valium to start , which is a brand name
11:23 for days . A pan , the chemist Leo Sternbach
11:25 and has gifted technician barrel Kapil discovered the first of
11:28 this family of compounds by accident in the mid 19
11:31 fifties called Claudia's Up oxide . Capital had been screening
11:34 potential muscle relaxants for seven years when she found that
11:38 this compound had anxiety reducing effects . A few years
11:41 later , the discovery of diazePAM followed these drugs quickly
11:45 became popular because they reduce anxiety and tension without the
11:48 knockout effect of something like chloral hydrate . These days
11:51 , doctors are increasingly cautious about prescribing them because they're
11:54 habit forming cause respiratory depression and long term use is
11:58 associated with cognitive impairment . However , despite its complicated
12:01 medical history , diazePAM is a useful example for carbonell
12:05 chemistry . Let's focus on one part of its synthesis
12:08 involving the top bit of the molecule with a clear
12:10 acetate . A likely mechanism starts with the carbon attached
12:13 to the chlorine being attacked by nuclear filic ammonia ,
12:16 replacing the chlorine with N H two . In an
12:18 SN two reaction . After that , you'll notice we
12:21 have an amine , nice and close to a carbon
12:23 Neil group . That carbon Neil group is irresistible to
12:26 the nuclear filic nitrogen . And it attacks forming the
12:29 I mean that is part of diazePAM . This inter
12:31 molecular reaction closes the seven member ID ring . That's
12:34 a signature part of this family of medicines . Overall
12:37 in this episode , we've learned that Aldo hides can
12:40 form hydrates and water and formula is a particularly important
12:44 example . The two animals of the hemi astral form
12:47 of glucose are connected by a reversible reaction between al
12:50 to hide and alcohol groups . A settles can be
12:53 a useful way to protect carbon steel groups in longer
12:55 sin theses and it means and china means can be
12:58 formed from Aldo hides and ketones . That's it for
13:01 Aldo hides in key tones for now . But we
13:03 definitely haven't seen the end of these important functional groups
13:07 . They'll pop back up here and there . Next
13:09 episode will explore another kind of carbon heel containing chemical
13:13 the car bucks silic acid . Until then , thanks
13:15 for watching this episode of Crash Course Organic Chemistry .
13:18 If you want to help keep all crash course free
13:20 for everybody forever , you can join our community on
13:23 Patreon .
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