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Alkanes and Nomenclature

By James Ashenhurst

Meet the (Most Important) Functional Groups

Last updated: March 21st, 2021 |

Functional groups are specific groupings of atoms within molecules that have their own characteristic properties, regardless of the other atoms present in a molecule. Common examples are alcohols, amines, carboxylic acids, ketones, and ethers.

In a typical sophomore organic chemistry course, there’s about 14 functional groups that are key, with another group of 8 that make appearances from time to time. [You’ll meet others, too – this is just a selection of the most common]

Here are the most common functional groups encountered in introductory organic chemistry courses:

most-important-funcdtional-groups-alkane-alkene-alkyne-benzene-ring-amine-alcohol-ether-alkyl-halide-thiol-aldehyde-ketone-ester-carboxylic-acid-amide

Things to think about as you look at the list:

  • in each, what are the most and least electronegative atoms present?
  • which of the atoms will be electron-poor ( “delta-positive”) and which electron-rich (“delta negative?”)
  • Which functional groups will be capable of hydrogen bonding?
  • Which functional groups will be capable of dipole-dipole interactions?

The more polar the molecule, the stronger the intermolecular interactions and the higher the boiling point.  Which of these functional groups will tend to lead to the greatest increase in boiling points?

The more polar the molecule, the higher the water solubility. Which of these groups will tend to increase water solubility? Decrease water solubility?

The Supporting Cast

Then there’s a group of about 8 functional groups that you’ll see a little but less often but they still have their place:

less-important-functional-groups-in-organic-chemistry-nitrile-epoxide-disulfide-imine-acid-chloride-anhydride-nitro-sulfide

If you find that you’re having a hard time recalling the structures of the functional groups, I put together a quiz [flashcards on memorize.com] that might be useful.

00 General Chemistry Review
01 Bonding, Structure, and Resonance
02 Acid Base Reactions
03 Alkanes and Nomenclature
04 Conformations and Cycloalkanes
05 A Primer On Organic Reactions
06 Free Radical Reactions
07 Stereochemistry and Chirality
08 Substitution Reactions
09 Elimination Reactions
10 Rearrangements
11 SN1/SN2/E1/E2 Decision
12 Alkene Reactions
13 Alkyne Reactions
14 Alcohols, Epoxides and Ethers
15 Organometallics
16 Spectroscopy
17 Dienes and MO Theory
18 Aromaticity
19 Reactions of Aromatic Molecules
20 Aldehydes and Ketones
21 Carboxylic Acid Derivatives
22 Enols and Enolates
23 Amines
24 Carbohydrates
25 Fun and Miscellaneous

Comments

Comment section

28 thoughts on “Meet the (Most Important) Functional Groups”

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  4. sir the article was really nice and informative but I did not get what I wanted…
    my ques is
    I hve a substituted benzene with OCH3, NO2 and Br attached at 1, 3, 5 position
    so how will I name it?
    will it be bromobenzene or nitrobenzene…
    and in what order will I number the carbons acc to IUPAC?
    PLEASE PLEASE REPLY ASAP..
    I will be highly grateful.

    Reply

    1. Are you sure about the positions of Br and NO2 in this compound you have described. As it is a ether group, the functional group will be at the 5 position.
      Its name is 3-Nitro 5-Bromo benzyl methyl ether

      Reply

        1. Functional groups are named in alpha order if equivalent positions (3 or 5).
          Therefore 3-bromo, 5-nitro methoxybenzene or, since anisole IS recognized, 3-bromo, 5-nitro anisole.

          Reply

  5. This entire website is an amazing resource for MCAT studying. I’m surprised you don’t have a book deal yet. thank you thank you thank you!

    Reply

  7. Hi, I’m a bit stuck. I need to find out the boiling points of pentanoic acid and 2-hexanone which I’ve already done, and compared both to find that pentanoic acid has the higher boiling point. I then need to give some sort of example and then justify this but i am not sure how to do so, could you please help?
    Thankyou :)

    Reply

    1. hi Tanya! pentanoic acid has intermolecular H bridges, and hexanone, hasn´t. this fact accounts for the higher boiling point. greetings from argentina

      Reply

  8. I would move thiols to the second list, and move epoxides, imines, and acid chlorides to the first list. The latter two become incredibly relevant when discussing carbonyl addition/elimination reactions and enamine chemistry.

    Reply

  9. Hello, I would like to know what ester would be best to make my science teacher (Paul) fall in love with me, I was thinking something fruity, Many thanks XOXOXOXOXO

    Reply
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  11. There is absolutely no point in putting a list of names associated with molecular configuration unless you give a description of why a particular functional group is important in chemistry. One needs real scientific insight not just another lesson in learning a language.

    Reply

  12. 5 year late comment but still may matter for context, thiols are perhaps more significant in Biochemistry, see the functional group of Cystine, a particularly important amino acid.

    Reply

  14. Hi James,

    I am having a tough time these days justifying calling a hydroxyl group and alcohol group. Has this always been predominate? I was not trained this way and I can’t imagine calling something like an oxime, an alcohol.

    — Kyle

    Reply
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