Hey, everyone. So in this video, we're going to take a look at the hydrogenation of Triacylglycerol Molecules. Now recall that under this type of reaction, 2 hydrogens are added to 1 pi bond. We're going to say the conversion from double bonds to single bonds is going to cause a decrease in our levels of unsaturation, which will cause an increase in our melting point. Now, when we talk about hydrogenation, we can look at it in terms of complete hydrogenation or partial hydrogenation. We're going to say here, we're starting out with the same type of a triacylglycerol molecule. Here, we have the same types of fatty acid chains attached. They each have 1 pi bond apiece. And we're going to say here with complete hydrogenation, we're going to say this is when all carbon double bonded carbon bonds are reduced to single bonds. Because we have 3 pi bonds, this will require 3 moles of hydrogen gas. Now remember with hydrogenation when we talked about it in earlier chapters with alkenes and alkynes, we'd have to use some type of metal catalyst. Here, we're using Nickel as the metal catalyst of choice. Now, because it's a complete hydrogenation, all the pi bonds here get reduced. So now they're only single bonds. We've gone from an unsaturated fatty acid group of chains to completely saturated. With partial hydrogenation, we're going to say this is when some, but not all carbon carbon double bonds are reduced to single bonds. Here we have 3 pi bonds And at the end, we only have one left. Because there's only one left, we're going to say, we only used 2 moles of hydrogen gas. So, we were able to reduce 2 of them, leaving one behind. We're still using our Nickel catalyst. Now, here, a couple of observations. First of all, we're going to say, we noticed that the configuration went from cis here to trans here. And we're also going to see that this is commercially manufactured. You might see terms or hear about this or heard about this of partially hydrogenated oils. Now, here we're going to say here that partial hydrogenation converts oils to margarines whose ultimate consistency is based on the number of piebots. So this is a way of making margarines and different types of fatty acid or lipid products that you buy in the store. You can actually adjust the number of pi bonds you have at the end. This actually adjusts the hardness of different types of margarines that you might buy. Now, here we're going to say during hydrogenation, some of the double bonds can isomerize to produce, and as we see, we went from cis to trans here, so it can produce trans pi bonds. Another way we can look at trans is e configuration. You might hear the term trans fats. This is a way of producing trans fats. We know that trans fat fats can be deleterious or harmful to our bodies. Again, this can happen. We sometimes can't control the production of these trans fats. Back decades ago, a lot of things had trans fats, but the process has become more streamlined and more technically based, better based that we're able to eliminate a lot of trans fats from different types of foods. So again, something you might have heard about or read about, we can see its application here under this idea of partial hydrogenation. Right? So here, we don't reduce all the pi bonds, some that remain. There's a chance they may go from one configuration to another. In this case, we're going from the cis or z configuration to the trans or e configuration.
32. Lipids
Triacylglycerol Reactions: Hydrogenation
32. Lipids
Triacylglycerol Reactions: Hydrogenation - Online Tutor, Practice Problems & Exam Prep
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concept
Triacylglycerol Reactions: Hydrogenation Concept 1
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Video transcript
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example
Triacylglycerol Reactions: Hydrogenation Example 1
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Problem
ProblemDetermine a possible triacylglycerol molecule formed when linoleic acid undergoes partial hydrogenation and consumes 1 mole of hydrogen gas.
A
Palmeitoleic acid
B
Stearic acid
C
Linolenic acid
D
Oleic acid
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Problem
ProblemA triacylglycerol molecule in the form of linoleic acid consumes 2 moles of hydrogen gas. Which of the following fatty acid represents the product formed?
A
Myristic acid
B
Stearic acid
C
Palmitic acid
D
Oleic acid
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Problem
ProblemAssuming a complete reaction with hydrogen gas, which of the following molecules would have the greatest increase in melting point?
A
B
C
D