Organic Chemistry

Learn the toughest concepts covered in Organic Chemistry with step-by-step video tutorials and practice problems by world-class tutors.

2. Molecular Representations

Functional Groups

We can group millions of different molecules into families of similar functionality.

1

concept

Why we need functional groups.

clock
1m
Play a video:
Was this helpful ?
1

Hydrocarbons

2

concept

Recognizing different types of hydrocarbons.

clock
2m
Play a video:
Was this helpful ?
0
Content
  • All carbon groups regardless of size can be symbolized using an –R group.
  • When an alkane is attached to a greater carbon chain, it is given a –yl suffix
    • An alkane turns into an alkyl group.  
Content
3

concept

How to assign degrees to carbons and hydrogens.

clock
1m
Play a video:
Was this helpful ?
0
  • Carbons are given a “degree” based on how many other carbons they are attached to.
    • Degrees are expressed as primary, secondary, tertiary and quaternary (1o, 2o, 3o, 4o)
    • Hydrogens possess the SAME degree as the carbon they are attached to 
4

example

Determine the degree of the indicated carbons and hydrogens.

clock
2m
Play a video:
Was this helpful ?
0
Content

Alkyl Halides

5

concept

Recognizing alkyl halides.

clock
1m
Play a video:
Was this helpful ?
0
  • Condensed Structure = -RX
  • The degree of the alkyl halide is determined the same exact way as hydrogen. 
6

example

Assigning Degrees to Alkyl Halides

clock
1m
Play a video:
Was this helpful ?
0
Content

Functional Groups without Carbonyls

Carbonyls are C=O bonds within a molecule. First we’ll learn about common functional groups that don’t contain these.  

7

concept

How to recognize alcohols, amines and ethers.

clock
5m
Play a video:
Was this helpful ?
0
Content
  • Alcohol Condensed Structure = -ROH
  • Amine Condensed Structure = -NH3, RNH2, R2NH, R3N
  • Ether Condensed Structure = ROR

These three functional groups completely change when they have a carbonyl next to them!

Functional Groups with Carbonyls

8

concept

How to recognize carboxylic acids, amides and esters.

clock
4m
Play a video:
Was this helpful ?
0
Content
  • Carboxylic Acid Condensed Structure = -COOH
  • Amide Condensed Structure = -CONH2
  • Ester Condensed Structure = -COOR

As you see, these functional groups are similar to the other ones, but have different names due to the adjacent carbonyl. 

Adding Carbonyls to Hydrocarbons

9

concept

The difference between aldehydes and ketones.

clock
3m
Play a video:
Was this helpful ?
0
Content
10

concept

How to write the condensed structures for aldehydes and ketones.

clock
2m
Play a video:
Was this helpful ?
0
  • Ketone Condensed Structure = -COR
  • AldehydeCondensed Structure = -CHO

These condensed structures aren’t very obvious. So just apply them to memory!

Nitriles

11

concept

How to recognize nitriles.

clock
27s
Play a video:
Was this helpful ?
0
Content
  • Nitrile Condensed Structure = -CN

Aromatic Hydrocarbons

12

concept

The difference between phenyl and benzyl groups.

clock
3m
Play a video:
Was this helpful ?
0
Content
13

example

Identifying Functional Groups

clock
2m
Play a video:
Was this helpful ?
0
Content

Other Carbonyl Compounds

14

concept

Recognizing acyl chlorides and anhydrides.

clock
1m
Play a video:
Was this helpful ?
0
Content
15

concept

Recognizing sulfur compounds

clock
1m
Play a video:
Was this helpful ?
0

Since sulfur is directly under oxygen in the periodic table, it makes analogous structures. These have different names depending on whether the sulfur is terminal (like alcohol) or internal (like ether). 

Content
  • Thiol Condensed Structure = -RSH
  • Sulfide Condensed Structure = RSR

 

Alright, now who's ready for some Practice Questions? Let's see if you can name all of the functional groups in the following 3 questions. 

 

If you get stuck, just pause the video and scroll up! 

16
Problem

PRACTICE:The following molecule contains several functional groups. Of the choices given, select the most appropriate answer (not all functional groups may be listed). 

17
Problem

PRACTICE:Identifying functional groups. Select the most appropriate answer. 

REMEMBER the A-TEAM gets degrees!

 

That is Alcohols, Alkyl Halides and Amines. 

Also, don't forget about Amides, they are part of the A-team as well.:)

18
Problem

PRACTICE:Identifying functional groups. Select the most appropriate answer. 

Congratulations, you made it to the end! Now let's move on to the next topic.