Multiple Groups When two or more of the same substituents are present, use the prefixes di-,tri-,tetra-,etc.to avoid having to name the alkyl group twice. CH3 CH3 CH:CH2CH2CHCH2CHCH2CH2CHCH3 109876,4321 CH3 Three methyl groups at positions 2,5,and 7. 2,5,7-trimethyldecane 2013 Pearson Education,Inc. Chapter 3 19 © 2013 Pearson Education, Inc. Multiple Groups • When two or more of the same substituents are present, use the prefixes di-, tri-, tetra-, etc. to avoid having to name the alkyl group twice. CH3CH2CH2CHCH2CHCH2CH2CHCH3 CH3 CH3 CH3 10 9 8 7 6 5 4 3 2 1 Three methyl groups at positions 2, 5, and 7. 2,5,7-trimethyldecane Chapter 3 19