Textbook Question
Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (x) D2 , Pd/C.
(k)
10. Addition Reactions
Hydrogenation
Problem 59b
Textbook Question
Identify the product when each of the following reactions is performed on the triglyceride of linoleic acid (linoleate).
(b) H2 , Ni (partial hydrogenation)
Verified step by step guidance1
Step 1: Analyze the structure of linoleate triglyceride. It consists of a glycerol backbone esterified with three fatty acid chains, each containing two double bonds in a cis configuration.
Step 2: Understand the reaction conditions. Partial hydrogenation involves the addition of hydrogen (H₂) in the presence of a nickel (Ni) catalyst, which selectively reduces some of the double bonds in the fatty acid chains.
Step 3: Predict the effect of partial hydrogenation. Under these conditions, one or more of the double bonds in the fatty acid chains may be converted to single bonds, resulting in a mixture of saturated and unsaturated fatty acids. The cis configuration of the double bonds may also be converted to trans configuration in some cases.
Step 4: Consider the product structure. After partial hydrogenation, the triglyceride will have fewer double bonds, and some of the double bonds may be converted to trans isomers. The exact product depends on the extent of hydrogenation and the selectivity of the catalyst.
Step 5: Note the implications. Partial hydrogenation is commonly used in the food industry to produce semi-solid fats, but it can lead to the formation of trans fats, which are associated with health risks.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Triglycerides
Triglycerides are esters formed from glycerol and three fatty acids. They are the main constituents of body fat in humans and animals, as well as vegetable fat. In the case of linoleic acid, a polyunsaturated fatty acid, its triglyceride form can undergo various chemical reactions, including hydrogenation, which alters its saturation level.
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Partial Hydrogenation
Partial hydrogenation is a chemical process that adds hydrogen to unsaturated fats, converting some double bonds into single bonds. This process can increase the stability and shelf life of oils but may also lead to the formation of trans fats. In the context of linoleate, partial hydrogenation will convert some of its double bonds, resulting in a product with fewer unsaturated sites.
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Linoleic Acid
Linoleic acid is an essential polyunsaturated fatty acid that is crucial for human health. It contains two double bonds and is classified as an omega-6 fatty acid. Understanding its structure and properties is vital for predicting the outcomes of chemical reactions, such as hydrogenation, which can affect its nutritional value and physical characteristics.
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