hello everybody my name is Iman welcome back to my YouTube channel today we're going to tackle a practice problem set that relates to our carboxilic acid lecture let's go ahead and get started the first problem says which of the following compounds would be expected to decarbox when heated now in lecture we said that decarbox occurs with beta keto acids and beta dicarboxylic acids because they can form a cyclic transition state that permits simultaneous hydrogen transfer and loss of carbon dioxide actually if we go back to our electron notes we saw how decarbox describes the complete loss of the carboxy group as carbon dioxide and we saw that we can take a car a carboxilic acid molecule that is in acidic conditions and then we heat it up and how this intr molecular reaction occurs that results in a hydrogen transfer and loss of carbon dioxide again the key Point here is it can occur with beta keto acids and beta dicarboxylic acids and so what we're looking for all right when we say beta is that there is one carbon between two carbonal groups but one of them has to for a carboxilic acid at least right so that's what a beta that that's what we what we mean when we say beta keto acid or beta dicarboxylic acid that means that there is one carbon between two carboxilic acid groups all right so here if we start to look at our answer choices all right a this molecule a has two carboxilic acid groups fantastic how many carbons are between those two groups right here in the middle one 2 okay that does not fit the criteria for beta dicarboxylic acid all right if we look at C same thing we have two carboxilic acids one two three carbons between the two carboxilic acids all right here if we that was C I'm sorry if we look at B all right B what we see here is a dietone it doesn't have a single carboxy group we need one carboxy group at least all right so it's not B either it's not a b or c if we look at D all right we have a carboxy group we have a ketone okay good This falls under the beta keto acid group all right and how many carbons are between those two groups one carbon this molecule answer Choice D this this compound is a beta keto acid all right a carbonal functional group at that beta position from a carboxy group that's the definition of a Beto keto acid all right either that or a beta dicarboxylic acid would DEC carboxilate when heated all right and so the correct answer for one is D two says carboxilic acids have a higher boiling point than their corresponding alcohols primarily because all right we're trying to figure out what is the main reason for this difference in Boiling Points between carboxilic acids and alcohols specifically why carboxilic acids have a higher boiling point than their corresponding alcohols answer Choice a says molecular weight is increased by by the additional carboxy Group B says the pH of the compound is lower C said acid salts are soluble in water and D says hydrogen bonding is much stronger in carboxilic acids than in alcohols all right let's break this down we are trying to figure out the primary reason now the boiling points of compounds really depends on the strength of the attractive forces between molecules in both alcohols and in carboxilic acids the major form of intermolecular attractions is hydrogen bonding for both of them however hydrogen bonding is much stronger in carboxilic acids as compared to alcohols why because because carboxilic acids are more polar and the carbonal also contributes to hydrogen bonding in addition to the hydroxy group all right so with an alcohol you have just an O group with a carboxilic acid you have an alcohol group and you also have a carbonal group all right so that's what we're referring to now the stronger hydrogen bonds that you see in carboxilic acids Elevate the boiling point of carboxilic acids compared to alcohols all right so the main primary reason that there is this difference in Boiling Points between carboxilic acids and alcohols is because of hydrogen bonding all right that's going to be answer Choice D all right now that's not to say that boiling point doesn't depend on something like molecular weight which is noted in answer Choice a all right boiling point also does depend on molecular weight but in this case the difference in molecular weight is insignificant compared to the effect of the hydrogen bonding all right and answer choices B and C they're they're both true but they don't actually explain the difference in Boiling Points all right those those statements they're not false statements they just don't relate to what we're trying to answer here all right so the answer for two is d three says which of the following carboxilic acids will be the most acidic all right now we have answer Choice a b c and d I went ahead and Drew those out for us all right and so what we're looking at is all these molecules all four of them have a carboxilic acid group and they all have the same number of carbons 1 2 3 four carbons all right same number of carbons and they all have one carboxilic acid group all right the difference between all of these answer choices is that this this one has no other groups besides just the hydrocarbon chain and the carboxilic acid group this one has one chlorine group all right it has a hallogen all right and it has a hallogen specifically one hallogen at the alpha position this one has two hallogen groups all right at the beta position all right it's at the beta position and this one also has one hallogen group at the beta position all right so we're trying to figure out which of the following carboxilic carboxilic acids will be the most acidic all right based off of only the difference in how many hallogen groups are present and where they are located now the acidity of carboxilic acids is significantly increased by the presence of Highly electronegative functional groups like these halogens we see here their electron withdrawing effects increases the stability of the carboxilate anion all right that that favors protein uh proton dissociation now this effect increases as the number of electronegative groups on the Chain increases and it also increases as the distance between the acid functionality and electronegative group decreases so what what that means is all right the acidity increases the more hallogen groups you have here all right and it will also the acidity will also increase if those hallogen groups are closer to the carboxilic acid group now we have this answer TR C we have one hallogen group that's at that alpha position all right for B we have two hogen groups at the beta position and then a we have one hallogen at the beta position all right so the so first and foremost all right the closer it is to that carboxilic acid group the better all right and so this one hallogen group at the beta position we're going to cancel out that cancel that answer Choice out and also D which has no halogens all right we have C where we have one hallogen close to the carboxilic acid group and here we didn't cancel answer Choice B just yet because it has two but at the beta position all right so this is what we're what we're you know comparing right now two halogens at the beta position versus one hallogen at the alpha position which wins over all right which of these is going to dominate over the other to give a more acidic carboxilic acid molecule and what the answer here is going to be is that more halogens all right is going to have a huger contributing factor all right it's that induction effect all right and so here this answer Choice C uh C sorry B has two halogens bonded to it all right and it's going to be the most acidic of the four answer choices all right so the correct answer is going to be B all right this is a tough one we were comparing B and and C all right where C had one hallogen at the alpha position but B had two halogens but at the beta position one carbon further all right what's going to conquer is having two of these electr negative um this this highly electron negative functional group being present all right two of them versus one that will win all right so answer Choice B for three four says which of the following molecules could be classified as soap all right fantastic so um I don't know why this says soup right here this is soap all right let's go over some information about soap that we learned from our lecture we said that soap is a salt of a carboxilate anion that has a long hydrocarbon chain all right that was our definition of soap now if we start looking at these an answer choices if we look at a all right a has a long hydrocarbon chain that right there all right but then it has this full carboxilic acid functional group that's not a salt a salt would be Co minus it would have be deprotonated and then it would have a cation that's associated with it all right hence salt so answer Choice a while we meet the long hydrocarbon tail criteria it is not a salt all right it's not a salt of a carboxy annion now if we look at B if we look at B we have no long hydrocarbon tail it is just a methyl group and a carboxilate group again this doesn't fit our definition of soap which is a salt of a carboxilate annion with a long hydrocarbon tail all right cool now if we go to answer Choice C okay we see that we have this long hydrocarbon tail it has ch2 repeated 19 times good all right and then it has Co minus all right carboxy annion very good and it has all right A cation associated with it this meets our definition of soap all right we have that long hydrocarbon tail and we have a carboxilate anion and if we look at D what we notice is it is a salt right we have that carboxilate anion but we don't have that long hydrocarbon and tail all right and so very clearly it becomes easy for us to figure out what the correct answer choice is for four it will be C beautiful five says what is the final product of the following reaction all right so what we have is ch3 ch24 then a ch2 so what we're seeing right here um is a primary alcohol that's what we have right there and it's being re it's going to react with chromium trioxide in aquous um sulfuric acid now we've encountered chromium trioxide before in this chapter in the previous chapters on alahh and ketones and even in chapter 4 when we were talking about analyzing organic reactions and by now we should be familiar that this is an oxidizing agent all right so what's going on here is that have a primary alcohol that is reacting with a strong oxidizing agent chromium trioxide is a strong oxidizing agent not just an normal oxidizing agent a strong one all right and so if we have this primary alcohol that's reacting with a strong oxidizing agent all right we know what this is going to result in all right it oxidizes that primary alcohol directly to a carox acid all right that means what changes here is what this carbon all right which is this carbon right here is going to be bound to all right if it's getting oxidized it won't be H2 and O those aren't going to be the three groups that carbon will have attached to it instead it's going to turn into a carboxilic acid so this carbon now will stay still have a bond to an O group but then a double bond to an oxygen and so if we're trying to figure out which answer choice is the result of this reaction we're looking for pretty much the same alkal change here alkal chain here all right the only difference is the ch2 is going to become Co all right right because now that carbon is the center the the the carbon of a carboxilic acid group and so looking at the answer choices here that's going to be answer Choice B we have the same alkal chain and then instead of ch2 we have our carboxilic acid group and so the correct answer for five is B says carboxilic acids can be reacted in one step let's underline that that's very important in one step to form all of the following compounds except blank we have Esters amides alkenes and alcohols now in the lecture video we saw that we can go from carboxilic acids to amides all right we saw that the you can go from carboxilic acids to amides amides are formed by nucleophilic AC substitution reactions with ammonia or an or an amine all right so that's obviously something that you can convert to from carboxilic acid in one step we saw that in our lecture we also saw that we can go from carboxilic acid to Esters in one step Esters are also formed in nucleophilic ACL substitution reactions with alcohols all right and we even talked about esterification all right so a is not the answer as well then we talked about how we can reduce carboxilic acids using lithium aluminum hydrides all the way down to primary alcohol or just to alcohols all right and that was done in one step as well all right so it can't be D carboxilic acids can be reacted in one step to form Esters amides and alcohols all in one step all right that's the note here but you can't go from carboxilic acid to alkenes in one step all right carox carboxilic acids cannot be converted into alkenes in one step to form alkenes carboxilic acids they can be reduced to alcohols which can then be transformed into alkenes by elimination in a second step for example all right but not in one step and so the answer to six is going to be C beautiful let's move on to question seven s says the reduction of a carboxylic acid using lithium aluminum hydride will yield what final product all right so we have a carboxilic acid we're going to use lithium aluminum hydride what is going to be our final product product well lithium aluminum hydride is a strong reducing agent and so it can completely reduce carboxilic acids to primary alcohols all right and so the correct answer for seven here is D all right we also just stated that when we were trying to tackle an uh problem number six fantastic eight says which of the following is true with respect to a m cell in a hydrophilic environment all right we're trying to figure out which is a true statement so three of these four options are false and one of them is going to be true let's read through them a says the interior of a myell is hydrophilic B says the structure of a myell as a whole is hydrophobic C says it is composed of short chain fatty acids with polar heads okay and D says my cells can dissolve non-polar molecules deep in their core cool let's remind ourselves a little bit of the information we covered about my cels in the lecture we said my cels they are selfassembled Aggregates of soap in which the interior part of a myel so if we look at this picture of a myel right here this interior part of a myel is going to be composed of long hydrocarbon tail which can dissolve all right all the interior is hydro hydrophobic then because it consists of long hydrocarbon tails that means you can dissolve nonpolar molecules all right in the center of this all right now the outer surface of a my cell it's covered with carboxilate groups which make the overall structure water soluble all right and so also the exterior is hydrophilic all right so interior hydrophobic exterior hydrophilic and that's because the interior is composed of long hydrocarbon tails and the ex exterior is made out of carboxilate groups fantastic now soaps in general then are salts of long chain hydrocarbons with carboxilate head groups then we can go ahead and now start to go through these answer choices for myol a says the interior is hydrophilic nope it's hydrophobic so this is incorrect B says the structure as a whole is hydrophobic again it's incorrect the exterior all right which is what's exposed is made out of is covered with carboxilate groups and that makes this structure water soluble all right and if it's water soluble it sure as heck ain't hydrophobic all right so B is also false C says it's composed of short chain fatty acids with polar heads all right not short chain long chain so this is also false d says it can dissolve non-polar molecules deep in its core this is true the core is hydrophobic and so you can dissolve non-polar molecules in the interior of a my cell so the correct answer here for eight is D nine says in the presence of an acid Catalyst the major product of butanoic acid and one pentanol is blank all right this is a really good question so what you have here is a uh butanoic acid this has carboxilic acid functional group and then one pentanol which is a primary alcohol all right the reaction between a carboxilic acid and an alcohol is called esterfication all right this is something we talked about in lecture and what happens here is that the nucleophilic oxygen of one pentanol is going to go ahead and attack this electrophilic carbonal carbon all right and ultimately it's going to displace water to form what's called pentanyl buttino all right it's going to form an Esther this oxygen is going to attack right here at this uh electrophilic carbonal carbon you break this double bond it dumps its electrons on oxygen fantastic we can draw this out step by step if we need to I'm going to um draw this out let's see how many 1 2 3 4 5 so 1 2 3 4 5 all right and so now you have this oxygen with a negative group all right you'll eventually also protonate this alcohol group so it becomes O2 and then what happens here is that we're going to reform this double bond we're going to dump the water all right we're going to dump the water and now what we have is this molecule right here which is an Esther and we know how to name Esters now all right it's Pentel which is this five carbon chain right here all right and then buttino it all right whatever this group is how many carbons it has butane that parent name you change it to ow it so buttin know it and so this molecule is called pen buto sorry takes me a while to spell that all right and so in this reaction the major product is pental buttino which is going to be answer Choice D all right so 9 is D 10 says the alpha hydrogen of a carboxilic acid is blank one says more acidic than the hydroxy hydrogen two says less acidic than the hydroxy hyd hydrogen three says relatively acidic as organic compounds go all right and we're trying to figure out how many of these are true if any all right so let's work through this here is a carboxilic acid molecule carboxilic acid containing molecule all right here is going to be that alpha position let's think about this the alpha hydrogen of a carboxilic acid it is relatively acidic as organic compounds go go and that's due to Resonance stabilization however here's the thing the hydroxy hydrogen this one right here all right the hydroxy hydrogen it's significantly more acidic because it's able to share the negative charge that results from deprotonation between this other oxygen right here so if this molecule got deprotonated and we lost that hydrogen all right if we lost this hydrogen the hydrogen would dump its electrons on the oxygen all right and now you have an oxygen with a negative charge you can form a double bond here and break this double bond and so now you have this resonance stabilization that happens between these two oxygens all right and that contributes to the acidity of this hydroxy hydrogen all right this hydroxy hydrogen is significantly more acidic and so if we look back at these answer choices all right the alpha hydrogen of a carboxy uh of a carboxilic acid it's not more acidic than a hydroxy hydrogen it's less acidic than the hydroxy hydrogen and it is relatively acidic as organic compounds go and so two and three here are true statements and that makes the correct answer for 10 D beautiful 11 says the reaction of formic acid with sodium borohydride will yield what for what final product so formic acid all right this is the structure for formic acid is this is a common name for methanolic acid it's one of those ones that we covered in lecture that you should know both the IUPAC name and the common name all right so this is a molecule that has a carox a carboxilic acid group all right and we are trying to figure out what happens when we treat this molecule with sodium borohydride now sodium borohydride is a mild reducing agent and something that we made note of in lecture is that mild reducing a mild reducing agent like sodium borohydride is not going to do anything to a carboxilic acid all right it's not going to reduce it in any way all right it's not going to reduce it to an alahh and it's not going to reduce it down to an alcohol all right you need a strong reducing agent in order to do that and so the correct answer here what is the final product when you react formic acid with sodium borohydride nothing will change so you will still have your carboxilic acid all right and so 11 is B all right fantastic let's go on to 12 12 says the intra molecular intra molecular all right I'm going to underline this word reaction of five amino pentanoic acid through nucleophilic acal substitution would result in a blank all right so what it's telling you is that this is what you're starting off with this is the molecules starting off with and things within this molecule are going to react with each other we have two functional groups here we have a carboxilic acid group all right and we have this amine group right here all right really we don't need to know the mechanism that's happening here we don't need to know the reaction mechanism exactly what you know what reacts with what or anything like that although we did talk about how this would happen in lecture right this is the only thing you would need to know to answer this question right because you have to be quick you don't have to worry too much about drawing out every step of a reaction especially if you know the key things to answer the problem what we have is a carboxilic acid and an amine group all right those are the two functional groups that are present here those are the two things that are going to be reacting with each other here what do we know about when you have a carboxilic acid and an amine group reacting through nucleophilic ACL substitution what's going to happen what's going to happen is that you will form all right an amide you're going to form an amide but what kind of amide this is an intr molecular reaction so things are going to react with each other within the molecule all right and specifically you're going to have your amine come here attack this uh electrophilic carbonal carbon you'll break this double bond you're going to probably hydrate this then you're going to reform the double bond and your oxygen leaves your your water leaves as a leaving group what you're going to form is an amide and specifically here a cyclic amide all right a cyclic amide because you have this intr molecular reaction happening all right one end of the molecule is forming a bond with the other end of the molecule all right so that forms a cyclic amide what do we call cyclic amides all right we call them lactum all right that was something we covered in our lecture lactum cyclic amides are lactum all right cyclic EST ERS were lactones all right make sure that you remember the difference between those two and so here our answer for 12 is going to be C beautiful 13 says butanoic and hydride can be produced by the reaction of butanoic acid with which of the following compounds all right so this is this right here is butanoic and hydride this is the product you're trying to form and they're saying you start off with one molecule of butanoic acid what does your other your second molecule need to be so that you can form butanoic and hydde now if you look at butanoic and hydride both sides all right have four carbon chains all right they both have four carbon chains which means that in order all right for butanoic anhydride to form which is an anhydride with two butan R groups you're actually going to need two molecules of butanoic acid all right and hydrides are produced by the reaction of two carboxilic acids with the loss of a water molecule and so that means butanoic and hydride would be produced by the reaction of two molecules of butanoic acid and so the other compound is just another molecule of butanoic acid 13 is a beautiful 14 says nucleophilic acal substitution is favored by Blink basic Solutions acidic Solutions leaving groups that are strong acids which of these are true let's figure it out nucleophilic ACL substitutions they're favored in basic solution and they're favored in acidic solution so one of the first things we we we stated was you can have nucleophilic AAL substitution reactions happen in either acidic or basic conditions so both one and two are true statements all right however this third statement leaving groups you know are favored by leaving groups that are strong bases this is not true all right strong bases don't make good leaving groups only weak bases do and so three is not true only one and two and that means the correct answer for 14 is going to be C last but not least 15 says the reaction of ammonia with cilic Acid found in coconuts would produce a blank all right you might look at this kind of problem when you're doing maybe a practice test and and potentially start to freak out right because maybe you didn't memorize what cilic acid is all right well based off of the name capric acid must be a carboxilic acid all right and so you have a carboxilic acid reacting with ammonia all right we know what this reaction is going to give us it's going to give us an amide but then if we look at the answer choices we see Esther anhydride alcohol water molecule none of these answer choices say amide and here you might maybe under the pressure of this test begin to stress out and think that you misremembered what the reaction between a carboxilic acid and an amine or ammonia gives you you might be like oh it's not an amide it should be an ester or an anhydride no you're absolutely correct it's an amide all right but what else do you get from this reaction besides that right and this is where you should remember what your leaving group for these reactions that we did were it was a water molecule all right water was our leaving group for these reactions that we've learned all right and so it was an amide and you had water all right water was your leaving group and you produced both an amide and a water molecule and that is the correct answer for 15 15 is D you would produce a water molecule all right I really hope this was helpful 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