hello everybody my name is Iman welcome back to my YouTube channel today we're going to continue chapter six of MCAT organic chemistry this chapter is about alahh and ketones and we made it all the way to objective two in objective two we're going to talk about alahh and ketones in regards to nucleophilic addition reactions so in each of the following reactions that we're going to cover today the general reaction mechanism is the same nucleophilic addition to a carbonal and this is one of the most important reaction mechanisms on the MCAT and many of the reactions of alahh and ketones and more complex molecules are going to share this General reaction mechanism so instead of just memorizing we are going to try to focus on overall pattern so that we can learn how a particular reaction goes about and we can use that same logic and apply it to more and more complex problems and we can also begin to apply it to other functional groups that we're going to see later down the line now as we've seen the carbonal bond it's polarized right there's there's a partial positive charge on that carbonal carbon and then there's a partial negative charge on the oxygen and that makes the carbonal carbon an electrophile all right ready for a nucleophilic attack now when the nucleo nucleophile attacks it's going to form a a coent bond to the carbon breaking the pi Bond of the carbonal all right so if you have a nucleophile all right and it attacks that electrophilic carbon it's going to form a coal bond to the carbon breaking the pi bond in the carbonal the electrons from the PIP Pond are pushed into the oxygen atom all right the oxygen is obviously going to happily accept extra electrons due to its electro negativity now it has extra electrons it h it possesses now a negative charge a full formal negative charge all right now breaking the pi bond forms a tetrahedral intermediate all right this is our tetrahedral intermediate anytime a carbonal is open you should ask yourself can I reform the carbonal if no leaving group is present all right the carbonal will not reform generally this oxygen with a negative charge will accept a proton from the solvent to form a hydroxy group resulting in an alcohol however if a good leing group is present the carbonal double bond can reform pushing off the leaving group now if no leaving group is present right the carbonal will not reform this is the case with alahh and ketones if a good leaving group is present the carbonal double bond can reform this is the case with carboxilic acids and their derivatives all right but understanding the general nucleophilic addition reaction mechanism will help you all right tackle any kind of problems whether it's with alahh and ketones as well as when we move down to uh when we move into other chapters and talk about carboxilic acids and their derivatives it'll also make more sense when we look at those mechanisms if we understand that a nucleophile will attack that electrophilic carbonal carbon all right and then when it does that it forms a calent bond to the carbon and that breaks the piie bond in the carbonal those electrons from the pi Bond they get pushed into the oxygen now the oxygen has a negative charge and there is one of two things that can happen you're if you have a good leaving group all right if you have a good leaving group the carbonal double bond can reform and if you don't have a good leaving group The carbonal will not reform so here we're talking about alahh and ketones all right we're not going to have a good leaving group generally speaking and instead what happens is from the solvent all right that oxygen with a negative charge will accept a proton from the solvent to form a hydroxy group all right so that is nucleophilic addition reaction mechanism all right because there's no good leing group that oxygen is proteinated to generate an alcohol now let's talk about hydration so in the presence of water all right alahh and ketones they react to form geminal diols all right one one dials all right that's what we kind of see here in this reaction me mechanism all right this hydration reaction it normally proceeds slowly but we can increase the rate by adding a small amount of some catalytic acid or base all right for a hydration reaction the carbonal is going to be all right the carbonal is going to be hydrated by water all right so water is the nucleophile here attacking the electrophilic carbon the it it forms a Cove valent bond to the carbon that's going to break the High bond in the in the carbonal those extra electrons go to the oxygen all right now this oxygen has a negative charge okay it can steal a hydrogen from the water all right and the hydrogen will leave behind its electrons and now what we have is a geminal dial we have two alcohol groups here all right so the carbonal is hydrated by water then proteinated resulting in a geminal Dion so that is hydration another important thing to talk about is acetals and Hemi acetals as well as ketal and hemiketal so a similar reaction occurs when alahh and ketones are treated with alcohols when one equivalent of alcohol which is going to serve as the nucleophile in this reaction is added to an aldah all right one equivalent of alcohol with an aldhy you're going to have a Hemi acetal all right the product is a Hemi aetl if you have one equivalent of alcohol with a ketone you're going to have a hemiketal all right Hemi acetals and hemiketals can be recognized by the retention of the hydroxy group all right the this halfway step all right hence the Hemi prefix is the npoint in basic conditions all right when two equivalents of alcohols are added all right with an aldhy then you're going to have an acetyl and when two equivalents of alcohols are added with a ketone you're going to have a keto all right so with two when two equivalents of alcohols are added the reaction proceeds to completion resulting in the formation of an acetal or ketal all right depending on if you're reacting those two equivalents of alcohol with an alide or Ketone respectively all right now we're going to look at what this looks like right cuz that was just a bunch of words but that never is enough for organic chemistry so let's talk about these reactions right so for example here's an alahh we're going to react it with first just one equivalent of alcohol all right and we're going to work through a Hemi acetal formation you notice that the oxygen in the alcohol functions as the nucleophile it's going to attack the carbonal carbon all right it's going to form a CO valent Bond and then the electrons in that Pi Bond all right are going to get dumped on the oxygen all right they're going to be pushed onto the oxygen atom of course the oxygen happily accepts that all right and then all right we're going to H we're going to um protonate all right we're going to that that oxygen with a negative charge is going to be proteinated all right and then what you get essentially is a Hemi acetal all right so if we were to draw out every step of this all right let's do that we have here our alahh all right this is very similar to the basics that we covered here we have an alahh we're going to treat it with one equivalent of alcohol the oxygen act as a nucleophile to attack the electrophilic carbonal carbon those electrons in the double bond get um the electrons in the pi Bond get pushed on the oxygen so now we have all right this Bond right here o and R and of course there's a positive charge and then this oxygen with a negative charge and then we're going to protonate the oxygen is going to take one of these hydrogens right here all right and as a final product now we have all right we have sorry we have two alcohol groups here all right two alcohol groups all right so that's how we went from alahh to Hemi acetal with one equivalent of alcohol all right so this is a Hemi aetl now if you treat it with another equivalent of alcohol two equivalents of alcohol total all right you're going to get an acetal which looks like this all right this is an R group right here okay so this is an acetal group so once an once the Hemi aetl is formed the hydroxy group is protonated and then then released as a molecule of water alcohol then attacks forming an acetal or ketal so that's how that's going to work all right and we and the same kind of concept with a ketone you treat it with one equivalence of alcohol you get a hemiketal all right and if you treat it with another equivalent equivalent of of alcohol two total equivalents of alcohol you're going to get a ketal all right notice the difference between Hemi acetal and hemiketal they both have this alcohol group this this ether group and a hydrogen for the Hemi aetl a hemiketal has that alcohol group has that ether group but doesn't have a hydrogen it has two alkal groups on both sides right because a ketone has two alkal groups um on each side of this carbonal uh group whereas the alahh has one alkal group all right and one hydrogen group associated with that carbonal all right and then similarly for looking at an acetal and a ketal the difference really is that while they both have these o groups two of them all right acetal has one alkal group and one hydrogen whereas a ketal has two alkal groups again makes sense looking at our starting structure all right and acetal the starting structure was an aldhy which has one alkal group and one hydrogen group attached to the carbonal carbon and it if you look at a keto it makes sense that it has two alkal groups because a ketone the starting product has two alkal groups attached to a carbonal group all right so that is acetal and Hemi acetals ketal and hemiketal all right now what we want to cover is am mines and enamines all right let's talk about this nitrogen and nitrogen based functional groups they act as good nucleophiles due to the lone pair of electrons on nitrogen and so they react readily with the electrophilic carbonal of alahh and ketones now in the simplest case all right in the simplest case which is what we see here in this figure in this uh reaction mechanism I should say ammonia adds to the carbon atom all right and water is lost producing an amine a compound with a nitrogen atom double bonded to a carbon atom all right that's what is shown in this reaction right here now because a small molecule is lost during the formation of a bond between to two molecules this is actually an example of a condensation reaction because nitrogen replaces the carbonal oxygen this is also an example of nucleophilic substitution all right so looking at this we have ammonia is added to the carbonal all right ammonia is added to that carbonal um the electrons of the pie Bond get pushed to the oxygen the oxygen gets protonated all right then the lone pair of the of the the lone pair associated with the nitrogen of ammonia all right forms a double bond between the carbon and nitrogen and then water gets pushed out as a uh leaving group so there this ammonia is added to the car carbonal and the result is elimination of water and that essentially results in generating an amine all right now amine and related compounds can undergo toiz to form enamines all right which contain a double bond which both which contain both a double bond and a nitrogen containing group all right now amines and enamines are things that we you spend quite a bit of time learning in organic chemistry 2 uh whereas the information that you need to know about this is pretty simple for the MCAT I just wanted to uh show this here as a friendly reminder I of course have an even more in-depth video on this topic um in my organic chemistry 2 playlist is chapter 19 all right but on that last note we said am mins and related compounds can undergo talization to form enamines all right that's depicted here all right um as a friendly reminder right you can talk about primary Ames and secondary amines for primary Ames in mildly acidic conditions an alahh or a ketone will react with a primary amine to form an AM me to form an amine all right that is seen right here so notice how we have an alahh group right here and it will react with a primary um Amine um to form an amine so you notice that this this um alahh group gets replaced with all right it reacts with a primary amine to form an amine so this this alahh group gets replaced all right and then with secondary am Mees well in acidic conditions an alahh or a ketone it will react with a secondary amine all right like this for example to form an enamine all right so for example here are some examples of primary amines that it could react with all right so for example this this shouldn't be written like this this is actually supposed to be this right here all right and so if you react this aldah with say this primary amine uh amine you can get this amine and same goes here right if you have this um aldhy or Ketone and you want to react it with the secondary amine you're going to form an n amine and this flowchart right here is just comparing amines and enamines right your starting group can be an alahh or Ketone and you can either uh treat it with a primary am uh amine sorry there's just so many similar words I'm stumbling over them all right you can treat your Ketone or alahh with a primary amine or a secondary amine all right and that will determine what kind of group you will form so if you're treating a ketone and alahh with a primary amine okay you're going to form an amine so what you notice here is that the carbon is now double bonded to a nitrogen all right amine but if you treat a ketona alahh with a secondary amine all right your result is going to be an enamine notice here that you have a bond between your nitrogen and carbon but the double bond is no is not between the carbon and nitrogen is going to be between the what was the carbonal carbon all right and the the the neighbor carbon all right so that's the difference all right between amine and and amine so that you can visualize all right there's for amine there's a double bond between the carbon and nitrogen all right there is not here for the enamine now one more thing we want to cover for objective two really quickly is cyan uh cyanohydrin all right so hydrogen cyanide this is a classic nucleophile on the MCAT it has both a triple bond and an electronegative nitrogen um atom rening it rendering it relatively acidic now after the hydrogen dissociates the nucleophilic cyanide anion right here like this right so if you're starting starting with um hydrogen cyanide the hydrogen can dissociate and you could be left with a cyanide anion has a negative charge it can attack the carbonal carbon atom like you see here right this attacking that electrophilic carbon all right and uh it's going to form a calent bond to that electrophilic carbon the electrons of the PIP Pond again are going to be pushed to the oxygen oxygen happily accepts it notice the trend here all right that Oxygen's now going to have a negative charge it can be protonated um or protonated by the solvent for example and then what you're going to form is a cyano hydron all right so reactions with alahh and and ketones all right are going to produce stable compounds called cyanohydrin once that oxygen has been reprotonated all right so this is a cyanohydrin reaction cyanide functions as a nucleophile attacks the carbonal carbon once the oxygen gets reprotonated generates a cyano hydrant with that being said we can move into our last and final objective which is talking about oxidation reduction reactions alahh Tides occupy the middle of the oxidation reduction spectrum they are more oxidized than alcohols but less oxidized than carboxilic acids ketones on the other hand are as oxidized as secondary carbons can get now first thing we want to talk about in this objective is oxidation of alahh now when alahh tides are further oxidized they form carboxilic acid so we said we can go from primary alcohol to alahh using mild oxidant like PCC all right now th that alahh product it can be further oxidized to form carboxilic acid any oxidizing agent stronger than PCC can perform this reaction all right so something like potassium pernate chromium trioxide all right even hydrogen peroxide or here we have written silver oxide all right any of these can further oxidize alahh to form carboxilic acids all right so most oxidizing agents will turn alahh into carox carboxilic acids PCC by by the way is not strong enough to oxidize past the point of an aldhy please make sure you know that all right and then also we want to talk about we want to talk about reduction by hydride reagents alides and ketones they can undergo reduction to form alcohols and this is usually performed with hydride reagents the most common uh the most common of these seen on the MCAT it's going to going to be either lithium aluminum hydde or sodium Borah hydde all right so if you treat a ketone or alide with lithium aluminum hydde or sodium borohydride all right you are going to reduce these ketones or aldhy to form alcoholes to form alcohol so notice how this Ketone is being treated with either lithium aluminum hydde or sodium borohydride and that Ketone is now just an alcohol all right so ketones are easily reduced to their respective alcohols using hydride reagents all right with that being said we have covered everything that we want to for this chapter in the next video we're going to tackle a practice problem set let me know if you have any questions comments concerns down below other than that good luck happy studying and have a beautiful beautiful day future doctors