Organic Chemistry: Exam 1

Formula for formal charge

# valence electrons - # of bonds - # unpaired electrons (total number not pairs)

describe s orbital

full circle

describe p orbital

• 1 empty orbital, 1 full orbital

• always 180* (straight)

how many orbitals in sp orbital?

2 orbitals

what is the shape of sp orbital

linear

what is bond angle of sp orbital

180 degrees

difference between sp and p orbital

p has one empty orbital, both sp orbitals are filled

how many orbitals in sp2

3 orbitals

what is shape of sp2

trigonal

what is bond angle of sp2

120

how many orbitals in sp3

4

what is shape of sp3

tetrahedral

what is bond angle of sp3

109.5

explain C NMR

• represnts types of atoms (sp3, sp2, sp, etc)

• each line represents unique C signal

In C NMR what does 0-80 range represent

• sp3 (4 groups)

• single bonds

In C NMR what does 50-80 range represent

• left end of sp3 range

• represents polar single bonds

4 examples of polar bonds

• C-O

• N-O

• O-H

• C-N

2 examples of non polar bonds

• C-C

• C-H

In C NMR what does 75-100 range represent

• sp orbitals

• triple bonds

In C NMR what does 100-200+ range represent

• sp2 orbitals

• double bonds

In C NMR what does 165-200+ range represent

• left side of sp2 range

• polar double bonds

explain IR spectroscopy

• represents types of bonds (single, double, C-H, etc)

where is the fingerprint region in IR spectroscopy

• 0-1500

• region ignored because info not unique to help identify

what does 1500-1700 range represent in IR spectroscopy

C=C

what does 1700-1800 range represent in IR spectroscopy

• C=O

• ketones

what does 2000-2100 range represent in IR spectroscopy

• triple bonds

• C≡C

• C≡N

what does 2600-2800 range represent in IR spectroscopy

• Aldehyde C-H bonds

what does 2800-3000 range represent in IR spectroscopy

sp3 C-H bonds

what does 3000-3200 range represent in IR spectroscopy

sp2 C-H bonds

what does 3300-3400 range represent in IR spectroscopy

sp C-H bonds

what does 3400-3700 range represent in IR spectroscopy

• O-H bond in alcohols

• N-H bonds in amines

what is the difference between alcohols and amines in 3400-3700 range

• alcohols have hill shape

• amines have spiked shape and are smaller

What is a single bond

• sigma bond

• σ

what is a double bond

• π + σ

• π bond between p orbitals

what is a triple bond

• π +π+ σ

• 2 pi bonds

rules for line-angle structure

• C’s not labeled

• Other elements labeled

• corner represents C

• H’s only labeled when not attatched to C

• Lone pairs shown

define axial

vertical bond

define equatorial

horizontal bond

is axial or equatorial bonds more stable?

equatorial

steps to determine Z vs E alkenes

1. split alkene vertically in 2 halves

2. name compounds on bonds

3. decide which group gets priority

4. split horizontally in line with double bond

5. groups on same side = Z groups on opposite sides = E

How to determine priority in Z or E alkenes?

If lone element: (bigger atomic #)

If compounds: the one with more carbons (ethyl has priority over methyl)

define constiutional isomer

• same # of atoms

• different arangeent of atoms

define stereoisomer

• same atoms

• connected same way

• different 3D arrangement

examples of stereoisomers

• E vs Z

• cis vs trans

• R vs S

define resonance

• all atoms in same place

• electrons distributed differently

• often “flipped”

4 steps to compare compounds:

1. same formula? if not compounds are unrelated

2. same connectivity? if not compounds are constituitonal isomers

3. same spacial arrangement? if not compounds are stereoisomers

4. If yes to all, they are identical

Bond order formula

(# bondingg electrons - # antibonding electrons)/2

Do eclipsed or staggered conformations have more energy?

eclipsed

are staggered or eclipsed conformations more stable?

• staggered

• lower energy is more stable

in staggered conformation, which bonds give off energy?

• C-C

• C-any element other than H

any involving H give off no energy

how to tell in line-angle structures w/ double bonds the more stable structure?

Structure where double bond is attached to more R groups