General Chemistry

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22. Organic Chemistry

Alcohol Reactions

As a result of the presence of their highly polarized hydroxyl (OH) group, alcohols can be involved in many organic reactions.

Types of Alcohol Reactions

Understanding Alcohol Reactions

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So here we're dealing with alcohols and their reactions were gonna say alcohol's could be easily identified by the presence of the hydroxyl group, which is just in O h group. Now we're gonna say, because of the presence of this highly polarized group, alcohol's can be, um, involved in many organic reactions. So one reaction that they're involved in is substitution reactions. So here, under this reaction, alcohol's react with hydro Halik acids. X here represents a halogen and the two hydro Halik assets that we look at our HCL and HPR, both of them being strong acids. Here they react with the alcohol to form an Al Kiel Halid. So basically our carbon will attach to a halogen here. Florida is too reactive to basically be used. So that's why we don't use HF and h i dinos so large and slow that we don't worry about that either. So that's why I want you looking at Chlorine and broening. Now, the easiest way to look at this reaction is the alcohol the O. H group will combine with the hydrogen from the acid and we're gonna lose water. As a result of the BR will be where that used to be. So we rewrite this formula. We put that halogen there, plus the water we lost. Now again, when you get toe, actually get to organic cameras, you'll learn something called the mechanism and see how electrons move around in order to create this new alcohol. Hallett. Since this is still chemistry and this is just an introduction to organic, we don't worry about those mechanisms, because at this point they would just highly confuse you. There's a few things you have to learn beforehand before you get to that step what you learn in organic chemistry. So the same thing would have happened if I use HCL, except a CEO would have been there instead of a BR. Now. Another reaction that alcohol can undergo is elimination reactions. Under this reaction, under the presence of concentrated acids such as phosphoric acid or sulfuric acid, and alcohol undergoes a dehydration to form an Al Keen, so two carbons will be double bonded to each other. So what winds up happening here is we use H two s 04 and we use some heat, which can be represented by a triangle. This causes us to lose water so we're gonna lose Ohh! And then one of the neighboring carbons will lose Ah, hydrogen as well. So we could lose in each year or even from one of these other two. So we lose an H and H and the carbon that loses the H and the carbon that loses an ohh. They double bond to each other in the process. So now we only have two hydrogen on this carbon and in double bonds to this carbon here in the middle. And again it could have happened toe one of the other two carbons. They could have lost an ancient double bombed that carpet and we get an alky in the process where two carbons air double bonded to each other. Now, another reaction that can occur is oxidation. Reactions here in alcoholism is seen as an al cane that has undergone in initial oxidation. So here we have a carbon structure with only carbon and hydrogen to form an alcohol, and a wage group is added, which is a partial oxidation. So the alcohol can then be oxidized to form either a key tone or a carbon cilic acid. So remember, carbon slick ass is when you have a carbon double bonded to know single monitor Noh. And a key tone is when you have a C double bond Oh, connected to a carbon on inside. Now here, we're going to say this is done with the strong oxidizing agent sodium Die chrome eight and A to see our tool seven and the strong acid sulfuric acid. So if we take a look, we're gonna have here initially a primary alcohol. Why is it primary? We look at the carbon in the connected to it as one group, and we say that that carbon is connected to anyone other carbon. That's why it's primary. And here, as a result of this reaction, this is gonna change in tow. Our car Pacific acid so becomes CH three c h two and that group becomes the car Pacific acid portion. So ah, primary alcohol will always change into a carbon select acid under this process. Now here, this is a secondary alcohol. Why? Because the carbon with the O. H. That carbon is connected to two other carbons. Secondary alcohols become key tones. So instead of making a car Pacific acid, what happens here is the carbon connected to the O H. It just becomes see double bond. Oh, everything else stays the same. And then finally we have here What a tertiary alcohol tertiary? Because that carbon with the O. H. Is connected to three other carbons. And we need to realize here is that tertiary alcohols cannot be oxidized, So we'd say here simply no reaction. So to get the correct answer here, you have the first identify the type of alcohol you have. Primary, secondary or tertiary. Once you do that, you'll know what your product will be at the end.

In Substitution Reactions we react an alcohol with either HCl or HBr to change the OH group into a halogen. 


In Elimination Reactions we react an alcohol with concentrated H2SO4 or H3PO4 to create an alkene. 


In Oxidation Reactions an alcohol reacts with an oxidizing agent and is transformed into carboxylic acid or a ketone