Organic Chem Class #7

1. Organic Chem Class #7 OB: Branched Hydrocarbons Drawing them, naming them, and ISOMERS TOO.

2. We’ll need lots of paper, and your thinking caps on. We’ve learned that ISOTOPES are chemically identical atoms with different atomic masses (different numbers of neutrons) which are the reason for average atomic masses being decimals. We’ve learned about ALLOTROPES, such as graphite and diamonds, both pure carbon, but bonded differently and with different properties. If you don’t believe that, try to take the regents with a diamond, or get engaged with a pencil! ISOMERSare organic compounds with the same chemical formula, but different structures, so they have the same molar mass, but totally different properties. Examples are ethanol and dimethyl ether (what are the structural formulas and the chemical formulas please (do this NOW)

3. ethanol + dimethyl ether CH3CH2OH and CH3OCH3 C2H5OH or C2H6O and C2H6O

4. Branched hydrocarbons will also be isomers. Count the carbon atoms, if all the bonds are single bonds, then equal numbers of carbons will be isomers even though the molecules are “different”. Try hexane and let’s draw 2,3-dimethyl butane.

5. CH3 2,3 dimethyl butane • CH3 There’s a methyl group hanging off of the #2 and the #3 carbon. Isomer to hexane.

6. Draw pentane and 2methylbutane. Are these isomers?

7. Isomers? YES!

8. Draw 3-ethyl hexane and 3methyl-4,5-dibromo hexane

9. Draw 7ethyl, 8-fluoro, 2nonyne

10. Draw all the heptane isomers, and name them, what is the chemical formula for heptane?

11. n-heptane (or normal heptane) 2-methylhexane 3-methylhexane 2,2-dimethylpentane 2,3-dimethylpentane2,4-dimethylpentane 3,3-dimethylpentane 3-ethylpentane 2,2,3-trimethylbutane -C-C-C-C-C-C-C -C-C-C-C-C-C- C • -C-C-C-C-C-C- • C • C • -C-C-C-C-C- • C • C • -C-C-C-C-C- • C • -C-C-C-C-C- • C • C • -C-C-C-C-C- • C C • C CC • -C-C-C-C-C-

12. Time to draw two posters, let’s see class 6B