PHAR2821 Lecture Notes - Lecture 2: Alkane Stereochemistry, Butane
Document Summary
Geometric isomers (due to restricted rotation about c=c) are also diastereoisomers. Named as cis/trans (each c must have the same substituent attached) or e/z (uses. Cis the identical groups on each c are on same side of c=c; trans opposite sides (z) the highest priority. Cip grounds on each c are on same side; (e) opposite sizes. Recognise the importance of ring strain and eclipsing/staggering of c-h bonds in the determination of conformer stability. Predict which isomer of substituted cyclohexane"s will be most stable. Conformations (conformers) can be interconverted by rotation about a single bond. Configurations are fixed geometrical arrangements which cannot be interconverted without breaking bonds. Less stable than staggered as a result of pitzer (torsional strain) caused by close proximity of electron pairs in bonds (repulsion). Anything bigger than a nitrogen is going to want to be far apart. Synperiplanar they are close together and interacting. More will be in antiperiplanar less interaction between electron clouds.
