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Ch. 4 - Alkanes and CycloalkanesWorksheetSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins
Ch. 26 - Transition Metals
IUPAC Naming
Alkyl Groups
Naming Cycloalkanes
Naming Bicyclic Compounds
Naming Alkyl Halides
Naming Alkenes
Naming Alcohols
Naming Amines
Cis vs Trans
Conformational Isomers
Newman Projections
Drawing Newman Projections
Barrier To Rotation
Ring Strain
Axial vs Equatorial
Cis vs Trans Conformations
Equatorial Preference
Chair Flip
Calculating Energy Difference Between Chair Conformations
Additional Guides
t-Butyl, sec-Butyl, isobutyl, n-butyl

When alkanes contain double or triple bonds, that totally changes the way we name the molecule. 

Concept #1: How to name alkenes and alkynes 


Let's go ahead and add a few more functional groups, so now we're going to talk about aklenes, alkynes, and alcohols.
So first let's start off with the pi bonds, with the double bonds and the triple bonds. Alkenes and alkynes are going to be named by adding a modifier. So this is going to be the very first time that we're using a modifier in an IUPAC name, so I'm going to teach you guys how to do this.
What that means is that instead of using the ending -ane, like we always use. It stands for alkane. Instead of using that ending we're going to use, we're going to modify it to either be -ene if it's an alkene or -yne if it's an alkyne. That's why we call it a modifier. It modifies the root name. So now all of the sudden, a hexane becomes a hexyne if it has a triple bond in it. Does that make sense? Cool.
So then let's talk about some important rules here. Alkenes and alkynes are actually going to receive priority in numbering alkanes. This is also going to be the very first time that now when it comes to numbering the chain, we are going to give priority to this group. What that means is that I don't care about the closest substituent, all I care about now is how do I give my double bond or my triple bond the lowest number possible. Isn't that interesting? So now I'm just saying how can I make that number as low as possible. That's all I care about.
Then, finally, this can get tricky because these double bonds go over two carbons, so sometimes it can be tricky what's the location. Is it the first carbon or the second carbon? The location is always assigned to the first double-bonded carbon or triple-bonded carbon.
So what I want to do here is I want to go ahead and name this compound. I want you guys to go ahead and try it first with the rules and then I'll go ahead and I'll give you the name.

Alkenes and alkynes are named as modifiers, meaning we add suffix modifiers to the root chain: 

Double and triple bonds get priority, so try to give them the smallest number possible. 

Example #1: Name the following compound 

(You may see alcohols at the end of the video above. If it is included in your textbook, the videos will be in the corresponding chapter).


To find it quickly, just type "Naming Alcohols" in the searchbar at the top of the page :).


Nice job, guys! Let's move on to the next topic.