CH 107 SI Summer 2015
Worksheet 10 Answers
1. Amines are derivatives of ______________ in which the nitrogen forms _____ bonds and contains ____ lone
pair(s) of electrons.
ammonia, 3, 1
2. What is the geometry about the nitrogen in an amine?
trigonal pyramidal
3. Draw the structure of an amine containing one hydrogen and two methyl groups bonded to the nitrogen. What
is the classification of this amine? How many hydrogen bonds can it form to water?
secondary, can form two H-bonds to water
4. What is the difference between common and IUPAC naming?
common naming: name each alkyl substituent in alphabetical order followed by the word "amine"
IUPAC naming: find the longest chain containing the nitrogen and change the alkane naming from -e to -amine and then
name all other substituents on the chain. Substituents on the nitrogen are named as N-alkyl.
5. How is an NH2 substituent named?
amino
6. What is the general molecular formula for saturated amines? What can always be said about the number of
hydrogens in these molecules?
CnH2n+3N
Amine will always have an odd number of hydrogens.
7. For the following amines give the common name, IUPAC name, and classification.
8. Why do primary and secondary amines have higher boiling points than tertiary amines?
They are able to H-bond to each other while tertiary amines cannot because they have no hydrogens attached to the
nitrogen.
9. Which of the amines is more water soluble in the following pairs and why?
In the first pair, the amine with the shorter alkyl chain (two carbons) is more water soluble. In the second pair, the
secondary amine is more water soluble.
10. What is the general reaction between a weak base and water? (Use ammonia as the base.) How do amines
change when reacted with water?
Amines become a type of ammonium cation with four bonds to nitrogen, a positive charge, and a tetrahedral geometry.
11. Draw the reaction between ethyl amine and hydrochloric acid. Label the free base and hydrochloride. How can
this reaction be reversed?
free base
hydrochloride
The reverse reaction occurs when the hydrochloride is reacted with a strong base, which regenerates the free base
along with water and a salt as products.
12. What characteristics of amine salts make them suitable for use in the synthesis of drugs? List at least two
common products containing amine salts.
They are water soluble and odorless and can be found in Benadryl, Sudafed, disinfectants, and soaps.