Which of the following compounds will react with Tollens' reag...

Question

Which of the following compounds will react with Tollens' reagent? With Benedict's reagent?

a. Cyclopentanon

b. Hexanal

c.

Accepted Answer

Hi, everybody. Let's take a look at our next problem. It says, determine whether the compound chan below will react to the following reagents. One Tallinn's reagent and two Benedict's reagent. And we have three different compounds labeled 12 and three. There are four answer choices labeled A through D list for each of these compounds, whether or not they're going to react with us to reagents. So we'll look at those in more detail when we work our way through our compounds. So first, let's think about what we use. Tin's reagent and Benedict's reagent for what's going on here. Well, Tallinn's reagent consists of a mild oxidizing agent. You have silver oxide A G 20 along with ammonia, water and heat scoot that down a little bit fit it better as a mild oxidizing agent, it will get reduced, causing aldehydes to be oxidized to carboxylic acid. So tolins reagent causes aldehydes to become carboxylic acids with keytones. It causes no reaction and the reaction it shows is a visible one. When the silver oxide gets reduced, it produces solid silver which precipitates out and coats the flask, producing this mirror like effect. Benedict's reagent is also a mild oxidizing agent. It consists of a copper two plus solution which is a blue solution. The copper gets reduced to copper plus in the form of C 20 copper oxide which is a red precipitate. And this reaction will occur in the presence of aldehydes. So, aldehydes which will get reduced to carboxy oxidized to carboxylic acids, excuse me. But it will also cause a reaction in the presence of alpha hydroxy ketones. So that would be when the alpha carbon, the carbon attached to the carbon carbon has a hydroxy group on it. We can draw that here a carbon with an oh and that carbon has a bond to a carbonel group. So the two reagents are both mild oxidizing agents both react with aldehydes. But tolins doesn't react at all with ketones. Benedicts can react with alpha hydroxy ketones. So with that in mind, let's look at our compounds. Compound. Number one, we see a 12345 carbon chain, the fifth carbon from left to right has an aldehyde group on it. We see that we have our carbonel group with a hydrogen attached on one side of the carbon and an alkyl group on the other. So this is an aldehyde. There are two hydroxy groups attached, one that is on the alpha carbon and then one that's two carbons away from that. But again, the presence of that alpha hydroxy carbon is only significant when you have a ketone, determining whether it will react with Benedict's reagents. This is an aldehyde. So it will react with both being oxidized to become a carboxylic acid. So when we have multiple choice like this, we should check in with our answer choices to see if we can eliminate any incorrect answers. We often can eliminate enough incorrect answers that we don't need to go through all the answers, all the uh all the problems presented to us. So we look at choice. A for number one, it says will not react with both Toland's reagent and Benedict reagent. So this is incorrect since it does react with both. So we can eliminate choice. A choice B says number 21 will react with both choice. C says number one will react with both and choice D says number one will react with both. So can't eliminate anything further. Let's look at number two, number two says four, methyl cyclohexane. So we have the one ending telling us that we have a ketone. So we know it will not react with Tallinn's reagent. We just need to check. Does it have an alpha hydroxy group? Well, there is no hydroxy group, as we can see in our name, this is a six carbon ring. It's a cyclo heaton with a carbonel group on one of the carbons and a methyl group on carbon four. So pera to that carbon group. So there's no alpha hydroxy carbon. So this will not react with either. So that, so let's look at our answer. Choices. We've already eliminated. Choice A choice B says that number two will not react with both Tallinn's reagent and Benedict's reagent. So that stays toy says will react with both T reagent and Benedict's reagent. So that's incorrect. Eliminating choice C for choice D number two says will not react with Toland's reagents. That's correct. But then it says will react with Benedict's reagent. So that makes number two incorrect eliminating choice T. So on the test, I don't need to do anything further. I circle choice B and keep going because this is a practice problem. We'll work our way. The rest of the way through looking at compound number three, compound number three is Butan L look at that A L ending tells us we have an aldehyde. So that will react with both its structure is a four carbon chain with an aldehyde group at the very end. But again, as an aldehyde, it will react with both Toland's and Benedict's solution. Double check answer. Choice B for number three says we'll react with both Toland's reagent and Bendix reagent. So once again, determining whether these compounds react with the following reagents. Tolins and Benedicts. The answer is choice B. Number one, we'll react with both. Number two will not react with either. And number three, we'll react with both. See you in the next video.

Which of the following compounds will react with Tollens' reagent? With Benedict's reagent?
a. Cyclopentanon
b. Hexanal
c. <IMAGE>

Key Concepts

Tollens' Reagent

Benedict's Reagent

Aldehydes vs. Ketones

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