CHEM 2100 Chapter Notes - Chapter 10: Bromine, Sulfuric Acid, Reagent
Document Summary
***number from end closes from alkene (dbl bond) before alkynes (trpl bond) before alkyl, halides. C trpl c in the middle of the. Hydrogen attached to one or both of c trpl c. Need strong base (amides, carbanion base, nah, nan) reagents. Like alkenes, alkynes can also be prepared by elimnation. Take an alkyl dihalide and do a double elimination. Removing 2h and 2 halogens to make trpl bond. Second elimination is so hard to do, need ultra strong bases ex. Need excess nanh2 to shift equilibrium toward elimination. Excess nanh2 results in terminal alkynide (c at end with negative charge) unless you. Throw in weak base like h2o to get us from alkynide -> alkyne. Equilibrium will greatly favor products product: alkynide ion (acetylide ion) React w/ h2 and pt to make alkane. If you react w/ h2 and pt, it will always result in an alkane. Two equivalents of h2 are consumed for each alkyne.
