worked example 15.1 drawing and classifying amines from their names
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Worked Example 15.1 Drawing and Classifying Amines from Their Names. Write the structure of N , N -diethylbutylamine and identify it as a primary, secondary, or tertiary amine. Analysis. - PowerPoint PPT PresentationTRANSCRIPT
© 2013 Pearson Education, Inc.Fundamentals of General, Organic, and Biological Chemistry, 7eJohn McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson
Worked Example 15.1 Drawing and Classifying Amines from Their Names
Look for terms within the name that provide clues about the parent compound and its substituents. For example, the word “butyl” immediately preceding the -amine suffix indicates that butylamine, the 4-carbon alkyl amine, is the parent compound. The N,N indicates that two other groups are bonded to the amino nitrogen, and the diethyl indicates they are both ethyl groups.
Analysis
Write the structure of N,N-diethylbutylamine and identify it as a primary, secondary, or tertiary amine.
The structure shows that three alkyl groups are bonded to the N atom, so this must be a tertiary amine.
Solution
© 2013 Pearson Education, Inc.Fundamentals of General, Organic, and Biological Chemistry, 7eJohn McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson
Worked Example 15.2 Naming and Classifying an Amine from Its Structure
Analysis
Name the following compound. Is it a primary, secondary, or tertiary amine?
The name is N-methylcyclohexylamine. Because the compound has two groups bonded to N, it is a secondary amine.
Solution
Determine how many organic groups are attached to the nitrogen. We can see that two carbon groups are bonded to the nitrogen. Since the cyclohexyl group is the largest alkyl group bonded to N, the compound is named as a cyclohexylamine. One methyl group is bonded to the nitrogen; we indicate this with the prefix N.
© 2013 Pearson Education, Inc.Fundamentals of General, Organic, and Biological Chemistry, 7eJohn McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson
Worked Example 15.3 Classifying a Cyclic Amine from Its Structure
Analysis
The following heterocyclic amine is named octahydroindolizine. Is it a primary, secondary, or tertiary amine?
In this molecule, three individual carbon groups are bound to N; it therefore is a tertiary amine.
Solution
Start by looking at the nitrogen; we can see that it is attached to three different carbons (as indicated by red, blue, and black bond lines). Even when the nitrogen is part of a ring, an amine will be classified by the number of organic groups that are bonded to it.
© 2013 Pearson Education, Inc.Fundamentals of General, Organic, and Biological Chemistry, 7eJohn McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson
Worked Example 15.4 Amines as Bases in Water
Analysis
Write balanced equations for the reaction of ammonia with water and for the reaction of ethylamine with water. Label each species in your equations as either an acid or a base.
Like ammonia, amines have a lone pair of electrons on the nitrogen atom. Because ammonia is a base that reacts with water to accept a hydrogen ion (which bonds to the lone pair), it is reasonable to expect that amines are bases that react in a similar manner.
Solution
Determine which species is the base and which is the acid. Remember that the base will accept a hydrogen ion from the acid. Review the definitions for a Brønsted–Lowry base (Section 10.3) and a Lewis base (Section 15.2).
Notice that in both cases water acts as an acid because it donates a hydrogen ion to the nitrogen.