5. Electrophilic Addition Reactions to Alkenes and Alkynes Flashcards
describe a general hydrohalogenation reaction.
there is a molecule with a double bond. A halogen is added to the carbon of the double bond that is more substituted and hydrogen is added to the opposite part
what are typical acids used in acid-catalyzed reactions?
strong acids like sulphuric acid, H2SO4, and hydrochloric acid, HCl
describe a general acid-catalyzed hydration reaction
there is a molecule with a double bond. A hydroxyl is added to the carbon of the double bond that is more substituted and hydrogen is added to the opposite part
describe a general hydroboration reaction
there is a molecule with a double bond. A hydroxyl is added to the carbon of the double bond that is less substituted and hydrogen is added syn meaning on the same side of the double bond
describe a general halogenation reaction.
there is a molecule with a double bond. Two halogens are added in a trans fashion on the double bond
what does cis mean in halogenation reactions?
only either wedge or dash
what does a double bond do to two halogens in a halogenation reaction?
consumes both the halogens
what does trans mean in halogenation reactions?
both wedge and dash
is an aromatic molecule reactive or unreactive?
unreactive
what do the bonds in the product look like for a benzene in a halogenation reaction?
wedge or dash bonds
what are the steps to solve a general ozonolysis reaction?
- cut the molecule in half from where the double bond is
- add oxygens to the ends of the double bonds
describe a dihydroxylation reaction.
there is a molecule with a double bond. two hydroxyl groups are added to either side of the double bond cancelling out the double bond
describe a general epoxidation reaction.
a double bond turns into a triangle with an oxygen
what is used in an epoxidation reaction?
RCO3H
what are the three types of hydrogenation reactions?
- reduction of alkynes and alkenes to make alkanes with H2 and Pd/C
- reduction of alkynes to make cis alkenes with H2 and Lindlar
- reduction of alkynes to make trans alkenes with metal or liquid ammonia
describe a general hydrohalogenation reaction in terms of hydrogens.
a double or triple bond is reduce with added hydrogens
what are the two partial hydrogenation reactions
-pausing at alkenes
- reduction of alkynes to make cis alkenes with H2 and Lindlar
- reduction of alkynes to make trans alkenes with metal or liquid ammonia
Describe the general reaction when there is reduction of alkynes to make cis alkenes with H2 and Lindlar?
A triple bond is turned into a double bond and two hydrogens are put on the same side of the double bond
Describe the general reaction when there is the reduction of alkynes to make trans alkenes with metal or liquid ammonia?
A triple bond is turned into a double bond as two hydrogen atoms are put in a trans fashion on a double bond
What are tertiary carbocations?
When one carbon has three other carbons surrounding it
What is a secondary carbon?
When one carbon is surrounded by two other carbons
What is a primary carbon?
When one carbon is surrounded by one other carbon
What is a benzylic carbon?
A carbon with a benzene ring
What is an allylic carbon?
carbon is bonded to a carbon atom which is double bonded to another carbon
Which type of carbocations is more stable
A carbocation that is more substituted
Why do carbocations rearrange?
To produce a more stable form
What is a 1, 2-hydride shift?
When a positive charge on a carbon switches spots with a hydrogen for the sake of stability
What is a 1,2-methyl shift?
With a positive charge on a carbon switches spots with a methyl group for the sake of stability
What is a terpene?
A five carbon isopropene
What are terpenes made from?
Dimethylallyl pyrophosphate, DMAPP or it’s constitutional isomer isopentenyl pyrophosphate, IPP
What is a key intermediate in terpene synthesis?
Geranyl Pyrophosphate, GPP
Describe a general terpene reaction?
There is a double bonded molecule with an OPP attached. The carbon with the OPP gives its electrons from its bond to OPP and gets a positive charge
What molecules are used above and below the arrow in an acid catalyze reaction?
H+ or H3O above the reaction arrow and water below the arrow
What molecule is used in a hydrohalogenation reaction?
A hydrogen attached to an halogen
What molecules are used in hydro boration?
BH3 and THF above the reaction arrow and H2O2 and NaOH below the arrow
What molecules are used above and below the arrow in halogenation reactions?
Two halogens above the reaction arrow and CCl4 below the arrow
What molecules are used in ozonolysis?
O3 above the reaction arrow and (CH3)2S below the arrow
What molecules are used above and below the arrow in dihydroxylation?
OsO4 above the reaction arrow and NaHCO3 or OH below the arrow
