Chapter 2: Alkanes and Cycloalkanes
In chapter 2, we learn some of the organic chemistry foundations such as naming alkanes using the IUPAC system, drawing Newman projections, and drawing chair conformations of cyclohexane.
2.1 The Structure of Alkanes
2.2 Constitutional Isomerism in Alkanes
2.3 Nomenclature of Alkanes and the IUPAC System
2.4 Cycloalkanes
2.5 Conformations of Alkanes and Cycloalkanes
2.6 Cis,Trans Isomerism in Cycloalkanes and Bicycloalkanes HOW TO: Convert Planar Cyclohexanes to Chair Cyclohexanes
2.7 Physical Properties of Alkanes and Cycloalkanes
2.8 Reactions of Alkanes
2.9 Sources and Importance of Alkanes
Naming Alkanes
Understanding PREFIX, INFIX, SUFFIX in organic molecules naming:
Following are IUPAC names and structural formulas for four compounds.Divide each name into a prefix, an infix, and a suffix and specify the information about the structural formula that is contained in each part of the name.
How to identify primary, secondary, tertiary and quaternary carbons
Write the IUPAC name for each cycloalkane.
Constitutional isomers are molecules with the same molecular formula
but different structure.
(a) Draw Newman projections for all staggered conformations formed by rotation from 0˚ to 360˚ about the carbon-carbon single bond.
b) Which staggered conformation(s) has (have) the lowest energy? Which has (have) the highest energy?
(c) Which, if any, of these staggered conformations are related by reflection?
Cyclohexane can adopt a lot of different conformations but there is one in particular that relieves both its angular and torsional strain. CHAIR
Following is a chair conformation of cyclohexane showing one methyl group
and one hydrogen.
(a) Indicate using a label whether each group is equatorial or axial.
(b) Draw the alternative chair conformation and again label each group as
axial or equatorial.
1. Draw the cyclohexane with the groups on it. Cis means both are either wedge or dash.Trans means one is wedge and another is dash.
2. Draw the chair and number the carbons on it 1 through 6 where 1 is on the top right going clockwise. Add substituted to the chair. Wedge= UP and dash= DOWN. If not sure, look at the up and down positions from the guideline above.
3. Draw the flipped chair and give 1 to the bottom right carbon. Add substituents.
Which cycloalkanes show cis,trans isomerism? For each that does, draw the cis
and trans isomers.
(a) Methylcyclopentane (b) 1,1-Dimethylcyclopentane
(c) 1,3-Dimethylcyclobutane
