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
Johnny Betancourt

A butyl group is a four-carbon substituent that can be arranged in four different ways, and each form has its own name. 


P.S. Check out my 4-hour lesson on nomenclature if you’re not in a rush!

What are all the different four-carbon substituents? 

There are four different ways to arrange a four-carbon chain as a substituent, so let’s check them out! I’ve drawn them out on a cyclohexane as the parent molecule. There are more complex ways to name these alkyl groups, but we’ll be focusing on the common IUPAC names here. Remember that we use the suffix -yl here because we're referring to an R-group coming off of a molecule. If these were standalone alkanes, we'd use the suffix -ane (e.g. isobutane instead of isobutyl). 

ButylButyl

This straight-chain butyl is called butyl, but you might also see it called n-butyl. “n” means straight-chain. It’s got only primary and secondary carbons.

IsobutylIsobutyl

This version, which looks a lot like isopropyl, is called isobutyl. It’s got primary, secondary, and tertiary carbons. 

Sec-butylSec-butyl

This version, which looks like isopropyl with an extra carbon at the end, is called sec­-butyl. It’s got primary, sSec-butylecondary, and tertiary carbons. 

Tert-butylTert-butyl

This version is called tert­-butyl. It’s got a quaternary carbon with three primary carbons coming off of it. Pro-tip: sometimes you'll see this abbreviated as t-bu. 

Hopefully this quick guide helps! Check out my videos on common substituents if you need a refresher!


Johnny Betancourt

Johnny got his start tutoring Organic in 2006 when he was a Teaching Assistant. He graduated in Chemistry from FIU and finished up his UF Doctor of Pharmacy last year. He now enjoys helping thousands of students crush mechanisms, while moonlighting as a clinical pharmacist on weekends.


Additional Problems
What is wrong with the name 1-t-butyl-2-methylpropane?a. The correct parent chain is butane.b. There are supposed to be 4 branches.c. There are supposed to be 5 branches.d. The correct parent chain is pentane.
Write the IUPAC name for the compound below. Be sure to use correct punctuation. Keep the information page open for guidance and for use with feedback. Accepted names for branched alkyl groups are isopropyl, isobutyl, sec-butyl, and tert-butyl. Do not use italics 
Click the "draw structure" button to launch the drawing utility. Write a structural formula for 4-tert-butyl-3-methylheptane. 
What is the IUPAC name of the following compound?
Write the IUPAC name for the compound below. Be sure to use correct punctuation. Keep the information page open for guidance and for use with feedback. Accepted names for branched alkyl groups are isopropyl, isobutyl, sec-butyl, and tert-butyl. Do not use italics. The IUPAC name is
What is the IUPAC name of the following compound?
Draw the structure of 4-sec-butyl-5-isopropyl-3-methyloctane in the window below . You do not have to explicitly draw H atoms.
1. Highlight the carbons in the appropriate longest carbon chain for naming the molecule below. 2. Type the name the molecule in the box. 
Spell out the full name of the compound.
Identify the alkyl substituents' systematic name and common name. a. 3-methylbutyl (isopentyl) b. 1-methylpropyl (sec-butyl) c. 2, 2-dimethylpropyl (neopentyl) d. 1-methylethyl(isopropyl)
Give the IUPAC name for this alkane.
Provide a systematic name of the following compound:
Draw the structure of 4-sec-butyl-5, 6-dimethylnonane.