Reactions of Carboxylic Acids

Video in TIB AV-Portal: Reactions of Carboxylic Acids

Formal Metadata

Title
Reactions of Carboxylic Acids
Title of Series
Part Number
12
Number of Parts
27
Author
License
CC Attribution - ShareAlike 3.0 USA:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor and the work or content is shared also in adapted form only under the conditions of this license.
Identifiers
Publisher
Release Date
2015
Language
English

Content Metadata

Subject Area
Abstract
This is the third (and final) quarter of the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: 00:20 - Reaction of Esters with Alcohols: Transesterification 02:03 - Reaction of Esters with Amines: Aminolysis 02:37 - Reactions of Carboxylic Acids 07:09 - Acid Catalyzed Esterification (Fisher Esterification) 14:30 - Conversion of Carboxylic Acids into Acid Chlorides 21:51 - Reactions of Amides 22:44 - Acid Catalyzed Hydrolysis of Amides 31:32 - Acid Catalyzed Esterification 32:14 - Reactions of Nitriles 45:12 - Irreverisble Addition Reactions of Type 2 Carbonyl Compounds
Loading...
Grading (tumors) Ester Reaction mechanism Carboxylate Carbonylverbindungen Alcohol Methylgruppe Chemistry Food additive Umesterung Common land Amination Solvolysis Acetone Optische Analyse Mixture
Ester Left-wing politics Reaction mechanism Carboxylate Walking Hydroxyl Carbonylverbindungen Namensreaktion Electronic cigarette Wine tasting descriptors Hydrogen Acid Etomidate Amination River Base (chemistry) Methanol
Ester Decomposition Reaction mechanism Carboxylate Resonance (chemistry) Ice sheet Chloride Hydroxyl Chlorine Ethanol Organochloride Electron Hydrolysat Elimination reaction Pyridine Thionylchlorid Bromide Walking Carbonylverbindungen Solution Alcohol Water Gesundheitsstörung Acid Functional group Etomidate Amination Bromine Cobaltoxide Base (chemistry) Methanol
Ester Reaction mechanism Carboxylate Resonance (chemistry) Substitutionsreaktion Hydroxyl Chloride Ammonium Electron Hydrolysat Colourant Conjugated system Setzen <Verfahrenstechnik> Stickstoffatom Walking Carbon (fiber) Aniline Carbonylverbindungen Protonation Solution Water Acid Gesundheitsstörung Functional group Amination Cobaltoxide Base (chemistry) Endotherme Reaktion Ammonia
Setzen <Verfahrenstechnik> Stickstoffatom Reaction mechanism Carboxylate Elektronenpaar Cyanogruppe Carbonylverbindungen Alcohol Chemistry Food additive Reactivity (chemistry) Water Ethanol Klinisches Experiment Ice Acid Nitrile Chemical compound Cobaltoxide Base (chemistry) Methanol
Reactivity (chemistry) Aldehyde Klinisches Experiment Ketone Cyanogruppe
Alkyne Biosynthesis Reaction mechanism Carboxylate Haloalkane Resonance (chemistry) Reactivity (chemistry) Klinisches Experiment Electron Hydrolysat Process (computing) Setzen <Verfahrenstechnik> Stickstoffatom Doppelbindung Tautomer Walking Carbon (fiber) Carbonylverbindungen Addition reaction Water Gesundheitsstörung Acid Cyanidion Functional group Azo coupling Etomidate Nitrile Amination Chemical compound Grignard-Reaktion Cobaltoxide Base (chemistry)
Stop codon Biosynthesis Ester Stickstoffatom Reaction mechanism Doppelbindung Ketone Walking Carbon (fiber) Alkoxide Carbonylverbindungen CHARGE syndrome Water Klinisches Experiment Dreifachbindung Acid Electron Functional group Amination Tetraederstruktur Aqueous solution Grignard-Reaktion Process (computing)
good afternoon we're gonna get started so everybody got their grade some people didn't look right so people don't look they're scared
they're afraid exams are going to the scanners today are they already at the scanners or going guys scanners today yeah okay so you should get the file back Thursday evening are there any questions before we get started I'm really happy with that mean that's a very good mean okay so your guys are on your way ready for the more difficult carbonyl chemistry that's coming up okay all right any questions before we get started all right we left off last time talking about transesterification sounds like something huh does sci-fi doesn't it okay so we we're definitely gonna have to drive the equilibrium because the esters are going to be same stability right so we have this ester right here at the Leicester methyl esters same stability so we have to drive the equilibrium to get one ester otherwise we're going to get a 50/50 mixture so on the top of the next page how do we drive the equilibrium common way to do it is to use excess alcohol or remove alcohol as it's formed all right so that's transesterification we can also take esters and convert them into a means this is called ammonolysis this is a reversible reaction let's do our reversible arrow here so we'll use excess amine in order for this to happen and you may want to try this mechanism out on your own just for fun all right and that leads us into reactions of carboxylic acids so you're may thinking
from what we've been talking about so far is you're thinking well we can go we certainly we can go back and forth between an ester and a carboxylic acid I'm thinking that because we went back and forth in a reversible reaction between an an ester and a carboxylic acid so we can probably take a carboxylic acid and convert it into an ester we're going to have to drive the equilibrium and you're may be thinking well it's easy to go downhill this way because that's what we've been doing easy to go downhill oh boy after a rolling start here let's try that again to an avid and you would be wrong about that can't go down here we can't go to an amen' easily and what so so the problem is is the acidic hydrogen gets in the way we know and we knew it we know we started off talking about carboxylic acids in that they're acidic and we know that this has a pKa of about 5 so it seems like we should be able to do this previous reaction that we did with an ester take the ester and cover it into an amine because that's a downhill reaction that should go but the problem is is when you add the amine to the carboxylic acid it now becomes deprotonated ok so once you once you add base to the carboxylic acid which you will if you're confided trying to convert it into an amide long arrow to the right short arrow to the left we get a carboxylate the carboxylate is the most stable lowest energy so so pretty much we're we are we going to be able to take the carboxylate and go uphill no or not ok so this is the most stable of all the carboxylic acid derivatives no stable we'll just say most stable of the all the carbonyls so once you once your deprotonated the carboxylic acid you get a carboxylate there are no downhill reaction because that's already as low as it goes energy-wise so that's a big problem with carboxylic acids and that's at the top of the next page here and I didn't I didn't I forgot that I already had this on this page but let's show it one more time just for fun and again bad electrophile so even if you took exit even if you used access I mean so let's say we decided we're going to use XS I mean the problem is that the carboxylate is not not electrophilic enough to have a second attack happen so even if excess amine won't work why an amine is not strong enough to attack a carboxylate so that doesn't work so we're looking pretty limited here with carboxylic acids aren't we we certainly can take them and convert them into an ester with acid we cannot do that with base why can't we convert wheat so when we when we took an ester to a carboxylic acid we could do with the acid or base when we convert a carboxylic acid to an ester we can only use acid why is that yeah if you form the carboxylate that's the end of the reaction okay so we really only have one astera fication of carboxylic acids and it has a name it hasn't it's a name reaction it's called the fischer esterification and so let's go through that so yes we can take a carboxylic acid and convert it into an ester using acid acid catalyzed reaction alright so it looks like that let's go through the mechanism and what you're going to find
when we're going through this mechanism is that it's going to look a lot like the reverse reaction where we took an ester and hydrolyzed it to carboxylic acid and that's we're actually tracing the same intermediates and it's just the same reaction in the river in the reverse direction so it's gonna look a lot the same I have a handout for these reversible reactions that I was going to give to you today but it is not the copiers are all down right now so I can't make any copies so we'll bring it next time alright so acid catalyzed mechanism we protonate the carbonyl to make it more electrophilic so that our weak nucleophile can attack our nucleophile is going to be methanol so what I encourage you to do is we're going to do this mechanism in the forward direction and what I encourage you to do is to try it also in the reverse direction and compare the intermediates and we'll see that you're gonna have the same intermediates I'm you're just going to be doing the opposite thing each time so if in the forward direction you're attacking with methanol in the reverse direction you're kicking off methanol alright so we've protonated the carbonyl we had our weak nucleophile attack we need to so the methanol is staying on so we're going to deprotonate and then we're going to lose one of the two hydroxyls your choice doesn't matter we're going to lis use one of the lose one of the two hydroxyls to convert the carboxylic acid into an ester so we don't want to do these combine these all at once we want to do this stepwise all right now of course we have equal likelihood of attacking either hydroxyl or the methoxy group and if we attack the methoxy group and that comes right back off we go right down to starting material and so all of these steps are reversible that's not a trot that's not a problem I'm going to now move to protonate one of these two hydroxyls I'll just do the one on the top and the reason I'm protonating that is this is an acid catalyzed mechanism in an acid catalyzed mechanism we always protonate
the leaving group before it leaves alright so now I'm going to have the electrons on oxygen come down and kick off the leaving group and you see when we do that we're one step away from having an ester all right so it looks like that we now we have to deprotonate and there's our Esther questions at the top yes well do we want to be making if we deprotonate the oxygen here do we want to be making oh - in an acid in an acid solution that's the problem with that okay so yeah we wanted we want to we'd not be we don't want to be creating oh - an acid catalyzed solution okay would have to say that again you don't need the second you you don't you some people don't some people the book leaves off this arrow and just has that leaving as a positive charge that's also fine that's just a resonance structure that product it's just a resonance structure of this one okay so it's totally fine if you did that on the test you got full credit for it alright more questions on that mechanism anybody so we have a summary sheet with all these acid catalyzed and base catalyzed mechanism so I'll be bringing that next time I think it's just acid catalyzed alright so once again we have a reversible reaction wrist reaction is catalyzed it's acid catalyzed hydrolysis of an ester and so's your favorites Tara fication of an alcohol excess alcohol or you'll even see excess carboxylic acid so we do a Fischer esterification in the lab that I teach and I and the students have to choose whether to use excess alcohol or excess carboxylic acid and so if it's a cheap saw if it's a cheap alcohol like methanol you can use alcohol as a solvent if it's methanol or ethanol to favor hydrolysis of an ester you want to a large excess of water alright so you can pretty much pick your conditions to favor or whatever you want you want carboxylic acid you can pick conditions to favor that you want an ester you can pick conditions to favor that alright so it seems like that's the only thing that we can do with carboxylic acids and basically what we said at the very beginning of this chapter is you can easily go downhill if you go uphill you have to use forcing conditions or a special reagent so here's where the special reagent comes in and you'll you're familiar with this reagent thionyl chloride so you remember that you acquired from chapter 9 the difference here is that in chapter 9 you used it to convert alcohols to alkyl chlorides and you used pyridine here we don't use pyridine we just use thionyl chloride and it would basically do the same thing it will convert that hydroxyl into a chlorine so how does that work well first of all let me just go let me down jumping ahead of myself here and so here's the problem here why we can't just use chloride ion to attack here if we do that if a chloride ion attacks here's our tetrahedral intermediate and as we discussed before the best leaving group is the one that's going to leave and the best leaving group here is on chloride so that's what's going to leave that's our best leaving group and so that's why we can't go from a carboxylic acid to an acid chloride so we'll go back to carboxylic acid alright so what about
what we're gonna do instead is use thionyl chloride you can also use pbr3 pyridine but it's much more common to use thionyl chloride how does this work I'm not going to go through the entire mechanism here so that means you won't be asked the entire mechanism but this is kind of this is what it looks like here same idea that we had back in chapter 9 here we have a bad leaving group and we're converting oh-h to a good leaving group so when I say how that means it's not really a complete mechanism and that also means I won't be asking you for the mechanism for this reaction but it's the same idea of what we did back in chapter 9 if you're curious about that so we had something like that and in Chapter 9 we would have deprotonated with pyridine here we don't have pyridine and so then in the second part of this reaction the chloride ion attacks the carbonyl but this time we have a good leaving group we have a leaving group that's competitive with chloride ion as a leaving group so we're going to attack the carbonyl addition and then we're going to eliminate we're going to eliminate we're not going to lemonade chloride we're going to eliminate this other sulfur-containing group so electrons on oxygen to come down and kick off this leaving group so second step elimination and what we've done is we've converted our carboxylic acid into an acid chloride an acid chlorides can now be converted into every single other carbonyl compound so it's a really good move to do this so we're really not limited with carboxylic acids because we can convert them into acid chlorides on the next page we also have PV r3 pyridine you can make acid bromide you can also use PCL 3 but most common reagent is thionyl chloride so indirectly carboxylic acids can be converted into every other carbonyl compound because we can convert them into acid chlorides first so to go from a to go from so we can we can do either either one this or the acid bromine so to go from a carboxylic acid into and an amide we would use step one final chloride step two two equivalents of amine or you can use one equivalent of a mean and what equivalent of pyridine your choice and we can go directly to to the Amadou there's some quite there's some problems in your book and this is the way they're gonna do this and we're knock I don't want you to do it I'm not going to give you points for it so don't try this this is in your textbook it's a bad reaction do in order to do that reaction you have to heat it above 200 degrees and most a lot of things decompose above 200 degrees so we're not using that method so if you need to take a carboxylic acid and you're going to convert that into an amide you're going to use this method here so use this instead so don't do on test questions about carboxylic acids anybody all right so what we're gonna do is we're gonna talk about a mitts and then we're going
to add another member to our type 2 carbonyl compounds that one might surprise you a little bit all right so can amaz be converted into any other carboxylic acids when everything is uphill and it turns out that you can do special reagents like we do with the sino chloride with Amin's you can use forcing conditions to go to a carboxylic acid or an ester this is forcing conditions it's an endothermic reaction and we do need to use heat when we're doing this reaction so if you're if you're going to be converting and Amidon to a carboxylic acid or an ester make sure that you include heat and that tells me that you understand that it's an uphill reaction alright so h3o plus h2o and heat so please include the heat there and this is the reaction if you had me last quarter that we did back in chapter 18 when we took annalen we converted in an acid annelids so that we could do aromatic substitution and then when we were done with that we hydrolyzed it right back off again right remember that now we're learning the mechanism so that I'm sure that's going to be deeply gratifying for all of you because you were wondering back then what was going on here's the mechanism by the way this reaction can be acid or base catalyzed I'm only going to ask you for the acid catalyzed I'm not showing you the base you don't need to look at the base the only one that you need to know is acid catalyzed so only need to know acid catalyzed hydrolysis of an ester not bass okay so that makes life a little easier for you alright and this is gonna look so much like acid catalyzed hydrolysis of an ester it's I hope that all of the mechanisms start starting to look really similar to you alright so what we're going to do is we're going to protonate the oxygen protonation of the carbonyl to make the carbonyl more electrophilic because we have a weak nucleophile attacking our weak nucleophile is water so we definitely want to protonate that carbonyl and if we took that NH 2 and converted it to an o CH 3 you'll see this is just the same we're just doing the same thing over again all right now water is going to attack our weak nucleophile is going to attack the carbon you know we're going to kick electrons up onto oxygen we're in the same position that we were with when we hydrolyze the ester we have this group that just came on that needs to stay on and then we have a new group that needs to come off and so the group that's going to stay on we deprotonate and the group that's going to leave we protonate and but we do this in two steps it does not happen simultaneously all right so we have the two hydroxyls those two hydroxyls are going to become the two oxygens of the carboxylic acid so they need to stay on we need we need to the amine to leave and of course in an acid catalyzed mechanism we always protonate the leaving group before it leaves so we're going to protonate nitrogen here so it's going to be ready to go so so far there's no difference here between ester hydrolysis and a mid hydrolysis only difference here is we're having to use a high heat here because it's a forcing conditions we're going up we're doing an uphill reaction okay now electrons on oxygen are going to come down your choice of which oxygen you want it should be nh3 right yeah caught that okay all right and then in the last step we're going to deprotonate oxygen we've got two possibilities here we've got water we also have pneumonia that's a stronger base than water so at that's and it's right nearby so we're going to use that and sapling kind of makes a big deal about these amines that are generated in an acidic solution they're always going to be protonated so you'd probably ran across that when you were doing sapling okay so that will definitely be protonated and again if you think back to chapter 18 if you had my class last quarter we had if we were actually looking isolating the amine which was aniline and we had if we had to add a base to deprotonate that okay so that's what that's all about questions well you know what you could use water here but let's see what the difference is so let's do this or water if you if you use if you use h2o to deprotonate you will if used h2o in this step right here to deprotonate let's do a different color arrow to show what that looks like if use h2o to deprotonate then you're gonna have h3o plus you're also going to have the ammonia that you just kicked off right and you're going to get an acid-base reaction that's highly favored to the right where you have ammonium ion and h2o alright so this is minus one point seven for this acid this is ten so it really hardly matters what you use to do that deprotonation okay you're still going to get the same thing all right more questions on acid catalyzed yeah why isn't the nitrogen initially protonated um let me see if I can find a spot to show that we talked about that when we at the very beginning when we talked about an ester and we protonated on the carbonyl oxygen rather the ester and it's the same reason let me just show that here if we protonate on that oxygen versus this we get a resonance stabilized conjugate acid just like that and that's real happy okay if we protonate on nitrogen you don't have any resonance stabilization so it's actually more stew you had a more stable conjugate acid when you protonate on oxygen but a great question because we think of nitrogen is more basic but a nitrogen is in that when we do the second resonance structure nitrogen is acting as a base so it's happy to okay it's just a lot better all right more questions same thing acid catalyzed this tariff occation and and so I don't need to go
through the mechanism of that because it's going to be just the same the only difference here when the acid catalyzed this tariff ocation is that we will be attacking with an alcohol here so say methanol or ethanol instead of water every otherwise it's exactly the same all right so let's draw the product in the Rieger space i have left here same mechanism as above except methanol attacks instead of water and I bet and I'm not gonna do this but
I bet if I had you guys take out a piece of paper and draw that mechanism you most of you would be able to do it right now so I'm not gonna do I'm not gonna take the class time to do it but I know that you can do that all right and that leaves us two night trials not an obvious thing to talk about in a chapter that's on carbonyl chemistry but their concern I trolls are considered carboxylic acid derivatives because like all type 2 compounds they react with water to form carboxylic acids and so they're considered to be in this category so we need to know a little bit about reactivity how reactive are nitriles they're less reactive than a mats so if you're thinking about our order stability they're gonna be under amédée but above carboxylates reactions in bass are slower because nitrogen is less electronegative than oxygen it accepts electron pairs less readily and they're less reactive and acid because there are so much less basic nitrile ice nitriles hydrolyze even more slowly than emits so we need
to keep that in mind result is that we must use even more forcing conditions and that equals higher heat all right so here's our order of reactivity okay so you see nitriles here right there and of course aldehydes and ketones are right here so what that means is I could ask you another ranking problem on midterm two or the final include nitriles in there and you'd know where to put them right yeah okay you could I think most of you got that right on the test although I
have no idea I'm just anticipating the most you got that right okay so let's focus on night trials here and what they can do so it turns out we can go uphill here
forcing conditions and we can easily go down easy easy downhill reaction and that's because of this certainly the order of reactivity less reactive than Ammons and more reactive and Karabakh carboxylates all right so let's do um let's look at the acid catalyzed hydrolysis that's the calles hiya hydrolysis of a nitrile I'm just gonna show you acid catalyzed there's also base catalyzed but I won't be asking you to learn that so just a sit again for this one here let's go through what the mechanism looks like so we can take a nitrile we can convert it into a carboxylic acid alright so let's go through that mechanism so we have our nitrile we have an acid catalyzed mechanism and where we're going to do is we're going to protonate nitrogen first so this is similar to protonating a carbonyl oxygen first that makes it more electrophilic so that a weak nucleophile can attack and we really need to help this nitrile out because it's not as electrophilic as a protonated carbonyl so water is going to come in and attack just like attacking carbonyl boom we kick electrons up onto nitrogen okay now that water is going to stay on that's going to become one of the two one of the two oxygens of the carboxylic carboxylic acids so since that's staying we're going to deprotonate that so we've got even more choices here for possible mechanisms for a midterm - whoops all right so we're used to seeing that carbon nitrogen double bond behaving like a carbonyl right and there's a couple of different approaches to this mechanism if you have a different approach and you want me to see what it looks like there's different ways to approach this mmm I'm trying to think of whether I should change it as I go here all right we'll just do it this way and I'm just changing my mind here let's do it this way so remember tautomerization of remember tautomerization of alkynes when we made all kinds and we hydrated and we taught our iced so what we can do I'm going to change this as I go here because I'm liking this more this is more like that so what we can do is so hopefully this mechanism is coming streaming back to you and then we drew up so we drew the resonance structure for that so there's the two resonance structures looks like that and now what's going to happen is we need another water to attack because we have two oxygens in the carboxylic acid and so water's going to come in and attack again this time it's going to attack our protonated carbonyl so this looks more like what you used to seeing this looks like now from here on out it's going to look like hydrolysis of a namet right the one we just did alright so that water that we just attack with we're going to need to deprotonate that staying we're going to have to protonate the group that's leaving which is the amine and that's definitely is going to take two steps to do that so this this this half of them this part from heat from this point on pretty much as soon as we attack with water here thats the whole thing's going to be exactly like hydrolysis of an amide all right so now the mean needs to leave we're going to protonate the amine we're almost there Mena's protonated ready to go electrons from either oxygen are going to come down and help kick that group off and now you can see we're one step away we just need to do protonate the carbonyl and we can do that with water or we can do that with an e it means right here water is also right here so it doesn't matter which one you choose for that so because of nitrous can be hydrolyzed to carboxylic acids and that means that they are considered to be type 2 carbonyls questions on that one anybody all right base catalyzed I'm not sure if that that page number is updated but it certainly is in your book that probably corresponds to the third edition but they have that there if you're curious about it but I will only ask you for the acid catalyzed all right so because night rolls can be prepared for reaction of an alkyl halide with cyanide ion that goes all the way back to chapter 9 we now have a synthesis of carboxylic acids from alkyl halides notice the carboxylic acid is one more carbon than the alkyl halide so this is also another way to add on one carbon so here's what it looks like straight sn2 reaction and then we hydrolyze that make sure that you include heat and we've done the same thing that we do with green yurts doing the same overall process here here's our
new carbon we add on co2 h of course we know another way to do this but that's making a grignard but sometimes maybe this is an this different strategy might lend itself better to particular types of compounds so that of course gives you the same thing questions on reversible editions of night trials anybody so now we're going to go back to chapter 20 material and talk about irreversible additions with my trials and hopefully what you've learned so far is going to enable you to
UM predict what's gonna happen here alright so this mechanism right here this was on the test right did we have this on the test so you'll see right now if you got it right or not okay so this is a very much a review reaction grignard attacks the carbonyl tetrahedral intermediate has leaving group and we're gonna use this same thought process to predict what happens with nitriles tetrahedral intermediate has a leaving group so electrons are going to come down and kick off that leaving group and then we had a we had a ketone we had to make a decision about whether the grignard was gonna attack the ketone or not and and yes you can't you can't stop here because green yurts are too powerful and it can't stop here but even more importantly can't stop here because ketones more reactive than an ester all right so the green yurts going to add again and we get a tetrahedral intermediate we are out of leaving groups the grignard added twice get an alkoxide and then of course once we add acid we protonate acid or water so that's the fast version of that reaction let's look on the next page and see if we can predict what's going to happen with the Nitro I'm not going to draw the product for you we're just going to predict alright so the carbon nitrogen triple bond kind of like a carbon nitrogen double bond kind of like a carbonyl so worth maybe you're thinking here boom we'll just go like this to attack that like that that seems reasonable right all right so now let's make a decision do we have a leaving group we don't have a leaving group and certainly not surprising because this is a reagent that is irreversible addition we don't have a leaving group will we have a grignard attacking again you think so what happens if occur in your detects again on what will be the charge on nitrogen let's suppose just do it let's do it in the air here okay so grignard comes in boom kick electrons up onto aught nitrogen what will the charge be on nitrogen to - is that gonna happen no so we don't we don't get attack again you only get attacked once so grignard won't won't attack again this would make and - - so it seems tempting because we see that carbon nitrogen double bond but if you draw the product and you look at the charge we you wouldn't want to do that okay so therefore it stops here and so it waits patiently around until you add water in a second step or add acid in a second step when you add acid in the second step here's the intermediate that you form and Amin but we know that amines in aqueous acid or not stable they would much rather go to a ketone so this is a synthesis of ketones from night trials and that's because the amine is not favored at equilibrium and we're going to go through the mechanism of how that amine gets converted into a ketone and
we'll do that next time on Wednesday
Loading...
Feedback

Timings

  354 ms - page object

Version

AV-Portal 3.19.2 (70adb5fbc8bbcafb435210ef7d62ffee973cf172)
hidden