hello everybody my name is Iman welcome back to my YouTube channel today we're continuing our chapter on carboxilic acids in the previous video we covered objective one we talked about nomenclature for carboxilic acids as well as physical properties of carboxilic acids today we move into objective two which is all about reactions of carboxilic acids all right now the first thing that we're going to cover under reactions of carboxilic acids is synthesis of carboxilic acids now as we described in previous chapters we mentioned briefly that carboxilic acids can be prepared via the oxidation of aldhy and primary alcohols now for this the oxidant is often something like a DI chromate salt so like sodium chromate or pottassium chromate or maybe chromium trioxide or even potassium permanganate all right and what happens is you can start with something like a primary alcohol all right then you're going to have your oxidant and you're going to get oxidation of that primary alcohol to get a carboxilic acid now I do want to note that there are many other methods of generating carboxilic acids you can use organometallic reagents like greenyard reagents and you can also do hydrolysis of nitril but these are not going going to be tested on the MCAT they're outside the scope of the MCAT so we're not going to cover it in our MCAT organic chemistry playlist however if you are interested I do have videos about those kinds of reactions in my oam 1 and 2 playlists all right so that is what we need to know for the MCAT how can we prepare carboxilic acids well they can be prepared via the oxidation of alahh and primary alcohols and these are the oxidants that you can use to to achieve that all right now the second kind of reaction we want to talk about is nucleophilic ACL substitution many of the reactions in which carboxilic acids and also carboxilic acid derivatives uh participate in they proceed through a single mechanism and that mechanism is called nucleophilic AAL substitution this mechanism is really similar to nucleophilic addition to an alahh or Ketone which we discussed in the last two chapters which were focused on alahh and ketones the key difference though is that this process nucleophilic ACL substitution focuses on the existence of a leaving group in carboxilic acids and their derivatives all right so for carboxilic acids this o group will be converted to water and that serves as the leaving group all right so what happens well you can have a nucleophile all right it's going to attack that carbonal carbon all right and then it's going to attach to that carbonal carbon this double bond um um dumps its electrons onto this oxygen now this oxygen has a negative charge and you have this um intermediate right here and so in this case after opening the carbonal through that nucleophilic attack all right what you're forming is this tetrahedral intermediate what can happen next is that that carbonal can reform all right that carbonal can reform all right but what happens before that is this alcohol group gets proteinated now your carbonal group reforms and that water group it leaves that water group is your leaving group so in short you have the opening of your carbonal through a nucleophilic attack you form a tetrahedral intermediate all right the carbonal can reform thereby kicking off the leaving group which is water because that alcohol was protonated all right so two big steps here just to help you remember the general process of nucleophilic ACL substitution you have a nucleophilic attack followed by the elimination of a leaveing group and a Reformation of your carbonal and you notice now that your end product still how has that carbonal carbon that carbonal group all right but now instead of an O group you have that nucleophilic group there in these reactions then what we can say is that the nucleophilic molecule replaces the leaving group of an AAL derivative all right and those ACL derivatives this is a this is a big category it doesn't just include carboxilic acids but it also includes carboxilic acid d uh uh derived carbonal so it includes carboxilic acids amides Esters and anhydrides and those are groups that we're going to focus on even more in the next chapter all right now something to remember all right is that these reactions are favored by a good leing group all right and the other thing to keep in mind is that weak bases which are often the conjugate bases of strong acids they make really good leaving groups and so these reactions they can be favored either acidic or basic conditions and that those conditions can alter the reactivity of the electrophile and nucleophile all right so that's all kind of buildup right we talked about what nucleophilic AAL substitutions are in general the two main processes that are involved in the mechanism and we said that you can do this with carboxilic acid groups you could do it with carboxilic acid derived groups all right and the main thing is that these reactions are favored by a good leaving group with that being said let's elaborate all right on nucleophilic AAL substitution going from carboxilic acid to say amides Esters and anhydrides all right let's start with amides carboxilic acids they can be converted into amides if the incoming nucleophile is ammonia or an amine all right an amine I'm sorry I should say an amine all right if the incoming nucleophile is ammonia or an amine this can be carried out in either acidic or basic conditions to drive the reaction forward and it's essentially you have your carboxilic acid all right you have your amine all right and they react together your water is your leaving group you're going to protonate the you're going to have your nucleophile again follow the mechanism of your nucleophilic ACL substitution nitrogen attacks carbonal carbon double bond will break all right then you your o will get proteinated you'll have water here all right then you reform your double bond water leaves as a leaving group you still have that carbonal carbon now but instead of having an alcohol group now you've attached your amine group right there all right and now you have an amide all right now you have an amide now just quickly we will re-elaborate on gnomen clature um in in future chapters but amides are named by replacing that o acid suffix with amide in the name of that parent carboxilic acid and any alkal groups on that nitrogen so if you had like an R group right here all right any alkal groups on the nitrogen are placed all the way at the beginning of the name with the prefix n all right so just quick nomenclature on the Fly we will reiterate this in later chapters now amides they exist in a resonance state where delocalization of electrons can occur between the oxygen and the nitrogen atoms all right so you do have a lone pair on your nitrogen here so you can you know form a double bond here you're going to break that double bond and now you have this resonance stabilization that occurs between this nitrogen and oxygen groups in your amide now you also might encounter um cyclic amides so amides that are cyclic are actually called lactum and they're named by replacing OIC acid with lactum um and you they they may be named they may also be named by indicating the specific carbon that is bonded during cyc cyclization of the compound so for example if you have a four carbon amide here's your NH and here you might have your all right if this is something that you form all right if you convert a carboxilic acid into an amide this is the amide you get this is called a a beta lactum all right for the and and then so this is called the beta lactum um it's indicating the specific carbon that is bonded during cyclization of a compound all right uh we're not going to get into this all too much besides that cyclic amides that are cyclic are called lactum and that their name is replaced with OIC that OIC acid is replaced with the lactum fantastic now the next thing that we want to cover under nucleophilic ACL substitution right we covered converting carboxilic acids to amides but what about Esters all right Esters are a hybrid between a carboxilic acid and an ether which can be made by treating carboxilic acids with alcohols under acidic conditions all right so this is happening under acidic conditions all right esterification is a condensation reaction with water as a side product all right so that this is the kind of process we're talking about so in acidic Solutions the carbonal oxygen all right can be protonated so what you're starting off with is this carboxilic acid where this carbonal oxygen has been protonated and that enhances the polarity of the bond which places an additional positive charge on the carbonal carbon and that increases its susceptibility to nucleophile attack attack all right and the thing to note is that this condensation reaction is going to occur the most rapidly when you have a primary alcohol reacting with your carboxilic acid in P in acidic conditions so here's our carboxilic acid in acidic conditions this oxygen has been protonated now we have our nucleophile this is our primary alcohol the oxygen of the primary alcohol will attack this carbonal carbon it will attach itself this double bond dumps its electrons on the oxygen here all right now this is under acidic conditions so your alcohol group here gets protonated all right you reform the double bond and this water group is the leaving group this gets dumped all right you form your double bond here all right with you reform this carbonal group but again your oxygen here is protonated your last step is to deprotonate that and you move from carboxilic acid to now you have an Esther all right so this process is called esterification reaction of a carboxilic acid with an aldah with an Al alcohol I'm so sorry all right this is reaction of a carboxilic acid with an alcohol to get an Esther all right Esters they're named in the same manner as salts of carboxilic acids all right so for example the Esther right here that we formed has a common name name ethyl acetate all right or the IUPAC name which is ethyl ethanoate all right so you name it very in a very similar manner as you would for salts of carboxilic acids don't worry we will revisit nomenclature for amides and Esters all right now one thing I also want to note is that Esters that are cyclic you can have cyclic Esters they're called lactones all right and they're named by replacing the OIC acid with lactone fantastic the next thing is anhydrides all right so under this category of nucleophilic AAL substitution we talked about um amides Esters and now the last category that we'll talk about is anhydrides anhydrides can be formed by the condensation of two carboxilic acids they're named by replacing the acid at the end of the name of the parent carboxilic acid with anhydride all right whether it's cyclic or linear so one example is the condensation of these two molecules of ethanolic acid to form ethanoic and hydride you notice that one o group or one of the hydroxy groups of one carboxilic acid of one ethanolic acid all right and the hydrogen of the other ethanolic acid are going to form a water molecule that that leaves all right hence this is a condensation reaction and through that process then you form a connection between these two ethanolic acids to form this anhydride that is known as ethanolic anhydride all right just like the previous reactions this anhydride formation occurs through nucleophilic AAL substitution fantastic that is everything we wanted to cover under nucleophilic AAL reactions so we've covered synthesis of carboxilic acids we've talked about nucleophilic ACL substitution reactions the next big category of carboxilic acid reactions is going to be reduction carboxilic acids can be reduced to primary alcohols by the use of lithium aluminum hydde lithium aluminum uh um lithium aluminum hydde is a really common strong uh reducing agent now aldhy intermediates can be formed in the course of this reaction but even when they're formed as in the course of this reaction they're intermediate and they will further be reduced to an alcohol all right this reaction occurs by nucleophilic addition of hydride to the carbonal group so from Li lithium aluminum hydride you can have the addition of a hydride to your carbonal carbon all right then your double bond breaks though that double bond dumps it electrons on the oxygen now this oxygen has a negative charge all right you can reform the double bond all right you can reform a double bond and then what you can have is that this alcohol group can can leave all right and then you have this alahh that forms then you can have another uh hydride interact here all right add itself to this aldah this double bond dumps its electrons on oxygen oxygen has a negative charge this oxygen is going to get protonated and at the end what we get is an alcohol and so this is the reduction of a carboxilic acid to a primary alcohol it occurs by nucleophilic addition of hydride and then it predes through an alahh intermediate remember lithium aluminum hydride is a strong reducing agent that can successfully reduce a carboxilic acid if you are going to use a gentler reducing agent like sodium borohydrate remember it's not going to be strong enough to reduce carboxylic acids all right it will not be strong enough all right sodium borohydride will not be strong enough to reduce carboxilic acids beautiful the next kind of reaction we'll talk about is decarbox decarbox describes the complete loss of the carboxy group as carbon dioxide this is a common way of getting rid of carbon from the parent chain all right so 1 three dicarboxylic acids and other beta keto acids they may spontaneously decarbox when they're heated up all right so when they're heated up they can go they can undergo decarbox under these conditions the carboxy group is lost and it's replaced with hydrogen now because both the electrophile and nucleophile are are in the same molecule the the reaction actually proceeds through a six-membered ring in its transition so if we can see here you're starting off with this molecule this carboxilic acid containing molecule all right the reaction is happening within this molecule all right the the only thing that's happening here is we're adding heat all right and then you go through this kind of Six membered Ring intermediate before we actually release carbon dioxide all right so this intr molecular reaction proceeds through the six membered rink transition state and then the product tzes from the enal to form a more stable keto form and so when you have this reaction that is occurring here all right in the same molecule you're going to have have the formation of an enal and carbon dioxide and then lastly that enal to tzes into its stable keto form and carbon dioxide is released that is decarbox last but not least we're going to discuss saponification when you have longchain carboxilic acids and you're going to have them react with something like sodium or potassium hydroxide what you're going to have is a salt being formed all right this process is called saponification and it occurs when uh it occurs by mixing fatty acids with li s sodium or potassium hydroxide and it results in the formation of a salt that we know as soap soap can solvate non-polar organic compounds in aquous Solutions because they contain both a non-polar tail and a polar carboxilic uh head all right so this carboxylic acid salt AKA soap has a non-polar tail and a polar head when placed in aquous Solutions soap molecules arrange themselves into a spherical structure that's called my cells the polar head faces outward where they can be solvated by water and then the non-polar Hydro carbon chains are oriented towards the inside of the sphere all right and so the polar heads interact with the hydrophilic environment the non-polar tails are oriented toward the interior of the myell okay with that we have covered all the reactions that we need for carboxilic acids let me know if you have any questions comments concerns Down Below in the next video we're going to t practice problems other than that good luck happy studying and have a beautiful beautiful day future doctors