Exam #2

Question 1

What is an alkane?

Answer 1

• saturated hydrocarbons
• no double or triple bonds
• lack functional groups

Question 2

What is a cycloalkane?

Answer 2

cyclic hydrocarbons

Question 3

What are the four steps of IUPAC naming?

Answer 3

1. finding the parent chain
2. identify and name substituents
3. number parent chain and assign locate to each substituent
4. arrange substituents alphabetically

Question 4

How is stability of alkanes determined?

Answer 4

• measured by heat of combustion
• branched alkanes are more stable (have lower heat of combustion

Question 5

Optically active definition.

Answer 5

compounds rotate plane-polarized light

Question 6

(+)Rotation

Answer 6

dextroratory

Question 7

(-)Rotation

Answer 7

Levoratotory

Question 8

If compound A is R and (+)

Answer 8

then, its S enantiomer is (-)

Question 9

If compound B is S and (+)

Answer 9

then, its R enantiomer is (-)

Question 10

Which one is optically active, chiral or achiral?

Answer 10

optically active- chiral
optically inactive - achiral

Question 11

Diastereomers

Answer 11

stereoisomers that are not mirror images
nonsuperimposable

Question 12

Enantiomers

Answer 12

nonsuperimposable mirror images

Question 13

Stereoisomers

Answer 13

same connectivity, non superimposable

Question 14

Meso Compounds

Answer 14

contain an internal plane of symmetry

Question 15

Atropisomers

Answer 15

compounds that have restricted rotation around a single bond, trapped in conformation
Ex: Biphenyls and Allenes

Question 16

Why is a chair conformation more stable than a boat conformation if they both have a bond angle of 109 degrees?

Answer 16

a boat conformation has torsional strain

Question 17

racemic mixture

Answer 17

a mixture of equal quantities of two enantiomers, or substances that have dissymmetric molecular structures that are mirror images of one another.

Question 18

What is mass spectroscopy?

Answer 18

• Not a form of traditional spectroscopy, doesn’t use electromagnetic radiation
• Bombards simple with electrons
• Primary Use: determine molecular weight and molecular formula

Question 19

What can mass spectroscopy be used for?

Answer 19

• forensic science
• drug development
• protein science

Question 20

What occurs in a mass spectrometer?

Answer 20

• a compound is vaporized, then ionized, and undergoes fragmentation
• The masses of the ions are detected and graphed
  -> High energy electrons collide with a molecule and produce a radical cation by displacing an electron

Question 21

Molecular Ion (M)*+ - The radical cation

Answer 21

• +1 charge on the radical cation
• no change in mass
• splits into an uncharged radical and carbocation (fragmentation)

Question 22

What is the base peak?

Answer 22

the tallest peak

Question 23

The (M)*+ Peak

Answer 23

• Has the full mass of the parent compound
• can be base peak if it is stable
• If peak has an odd m/z, likely contains nitrogen