Write the formulas and IUPAC names for the following common al...

Question

Write the formulas and IUPAC names for the following common alcohols.

a. Rubbing alcohol

Accepted Answer

All right. Hi, everyone. So this question is asking us to provide the Iupac name and formula of ISO AML alcohol, also known as Iso Peny alcohol. And here we have four different answer choices with four different Iupac names as well as formulas. So first and foremost, right, the first thing I want to point out here is that the name Isopto alcohol is reminiscent of Iso butyl alcohol. Now, the prefix iso is significant because the phrase Isophil indicates that there are going to be five carbons in total but not necessarily part of the parent chain. Now, the main thing that I like to remember is that structures with the prefix iso tend to have a kind of Y shape to it, right? Because when you consider an isopropyl group, for example, an isopropyl group is characterized by its sort of Y shape. So that's the the part that I like to remember. So because we have five carbons in total, in order to create that Y structure that's characteristic of ISO groups. So to speak, what I'm going to do here is I'm going to reduce the carbon chain or the parent chain by one. So I'm going to draw a four carbon chain and my fifth carbon is going to be added as a methyl group in the middle or on one of the middle carbons of the chain, right. So that creates the Y structure that, that I'm looking for. So because we're dealing with Isopto alcohol, then the hydroxy group is going to be attached to the carbon that is farthest away from the Y structure. So towards the very right side of the structure that I drew. So before this discussing the Iupac name, I actually want to go ahead and draw out my formula first. Like I discussed previously, our parent chain is actually going to be four carbons long and recall that when it comes to a formula, right, a condensed structure, then all hydrogens associated to a particular carbon as well as substituents are shown, right, and the number of hydrogens is dependent on how many bonds to other atoms that carbon already has. So for example, if you consider the carbon that is farthest left in the structure provided that carbon is primary, right, meaning it has only one other bond to in this case, another carbon atom. So because of this, the first carbon on the very left side is ach three because three hydrogens are needed to ensure that carbon has all four bonds that it requires. And so if I consider the carbon that is immediately to the right of the one that I just mentioned then that carbon is tertiary, meaning it has three bonds to other carbons, right? So that one is only missing one hydrogen and it is that second carbon that is connecting to an additional methyl group. So I would draw a line from the second carbon of the par chain and add on C three to showcase the substituent. So from there, I would do the same thing to the remaining two carbons, which would both be ch two, considering both of them have two bonds to other atoms. And then finally, I have my hydroxy group or oh group on the very right side of the structure connected to the carbon that is farthest to the right. So so far we have our structure. So now let's talk about our Iupac name. Now for the Iupac name, I'm actually going to go ahead and focus on the line structure or skeletal structure that I drew in the beginning of this video. Simply because for an Iupac name, hydrogens do not necessarily have to be shown, right? We can focus our attention on carbon as well as any hetero atoms like oxygen here. So if I consider the parent chain, right, we have four carbons in the longest continuous carbon chain and our primary functional group is an alcohol. So recall that when numbering your parent chain, we are going to start numbering the chain such that the functional group. In this case, the hydroxy group has the smallest possible number. So therefore, I'm going to go ahead and label my four carbons from right to left so that the hydroxy group is on carbon one of the parent chain. So a parent chain of four would have the name of butane. However, recall that depending on what functional groups may or may not be present modifiers are necessary to specify them, right. So in the case of this compound where we have an alcohol as the main functional group, then the E at the end of the parent name, in this case, the E at the end of butane gets dropped completely and replaced with the suffix OL. So we go from butane to butanol, but this isn't quite right either, right? Because in addition to adding the modifier, ol, a number is necessary to indicate the position of that hydroxy group on the parent chain. So in this case, I'm going to make some space in between oops my modifier here and the rest of my parent name because that is where I'm going to write the position number. So that separates into Butan one all. And so I wrote this as but 10-1 dash o to separate numbers from letters. So now that my parent chain has been named, right, I can go ahead and focus on any other substituents attached. So in this case, we only have one other substituent which is a methyl group on carbon three of the parent chain. So in the case of substituents, the position number is always placed before the name of the substituent itself. So I would write this S3 dash metal and I would place this in front of the name of my parent chain with no spaces in between. So it's all one word, right? So that becomes three dash metal, but 10-1 dash o. Now, in this case, there are some considerations to keep in mind when it comes to having multiple substituents present, like for example, adding prefixes when there are multiple copies of the same substituent and also arranging substituent names in alphabetical order. But in this case, we only have one substituent. So those rules don't necessarily apply. So that means that our final Iupac name is three Metal Ban one all. And that means that our final answer is going to be option c in the multiple choice and there you have it. So with that being said, thank you so very much for watching. And I hope you found this helpful.

Write the formulas and IUPAC names for the following common alcohols.
a. Rubbing alcohol

Key Concepts

Alcohols

IUPAC Nomenclature

Common Alcohols

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