Lecture 10 Outline of Last Lecture I Cyclohexanes a Chair conformation b How to drawOther conformations of cyclohexane c Chairs with ring flip d Chairs with a substituent CHEM 333 1st Edition i Diaxial interactions e Multiple substituents on rings Outline of Current Lecture I Properties of Alkanes II Synthesis of Alkanes III Stereochemistry a Isomers b Stereoisomers c Chirality i Enantiomers ii Plane of Symmetry Current Lecture I Properties of Alkanes a Not polar not miscible with water b Good for oxidizing burn fuel c 1 C to 4 C gas at room temperature cooking fuels d 5 C to 17 C liquid at room temperature gas e 18 C or more wax at room temperature candles f The higher the molecular weight the higher the boiling point i Example of Carbons Boiling Point 1 164 4 0 6 69 10 174 g Larger molecules higher boiling point more surface area therefore stronger interaction more interaction h Small molecules lower boiling point less surface area therefore weaker interaction less interaction i Constitutional isomers that are branched have lower boiling point and lower melting point less surface area less interaction i Example Higher boiling point Lower boiling point II Synthesis of Alkanes f Hydrogenization of alkenes and alkynes adding H2 to the pi system i Examples III Stereochemistry study of molecules as 3D objects f Isomers same molecular formula but different compounds g Stereoisomers same molecular formula and same connectivty but different orientation in space h Chirality the handedness of molecules Look at mirror images of superposable things If superposable not chiral If not superposable chiral i Enantiomers chiral molecules that have nonsuperposable mirror images of each other ii Plane of symmetry imaginary plane passing through an object dividing it so that one half is a mirror image of the other half 1 Not chiral achiral if you have elements of symmetry 2 Examples
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