organic reactions Flashcards
Addition reactions
- unsaturated molecule breaking to form a saturated molecule
Alkene/Alkyne breaking to form an alkane
substitution reactions
Replacing an atom/group with another group.
* adding something to a molecule AND
* there is a leaving group (taking something out)
elimination reactions
*saturated compounds becomes unsaturated by removal of 2 atom/ group of atoms.
alkanes becoming alkenes.
What are the 4 addition reactions
- Hydrogenation
- Halogenation
- Hydrohalogenation
- Hydration
What are the 3 Substitution reactions
- all single bonds (saturated)
- Hydrolysis (forming an alcohol)
- Forming of a haloalkane + acid
- Forming of a haloalkane + water
What are the 2 elimination reactions?
- Dehydration
- Dehydrohalogenation
Hydrogenation
addition of a H2
catalyst: Pt or Pd. (heat) / metal catalyst
Alkene + H2 → Alkane
Alkyne + H2 → Alkene
- Forward rxn = reduction (addition)
- Reverse rxn = oxidation ( elimination)
Halogenation
addition of a X2
catalyst: none, the halogen bonds are weak
Alkene + X2 → Haloalkane
radical substitution reaction
Acid catalyzed Hydration
addition of water
Catalyst: strong acid/an acid catalyst
Alkene + H2O → Alcohol
Hydrohalogenation
Alkene + HX → Haloalkane
- addition of an acid
- catalyst: none
no water must be present
Hydrolysis- formation of an alcohol
(substitution with a haloalkane)
haloalkane + H20 → Alcohol + Acid
haloalkane + strong base → alcohol + salt
formation of a haloalkane + acid
catalyst: light
Alkane + X2 → haloalkane + Acid
formation of a haloalkane + water
(Substitution with an alcohol)
Alcohol + HX → Haloalkane + H2O
Acid catalyzed Dehydration
(elimination with an alcohol)
catalyst: strong acids and high temperatures
Alcohol → Alkene + H2O
dehydrohalogenation
(elimination with haloalkane)
concentrated strong base
haloalkane + Strong base → Alkene + salt + H2O
alkenes/ Alkynes undergo
addition reactions
- substitution and elimination are less important in unsaturated systems
reduction reaction
whenever you add H to an organic compound
- Aldehydes and ketones are reduced to alcohols
- reducing agents: LiAlH4 and NaBH4
oxidation reaction
whenever you remove H from an organic compound
- Aldehydes are easily oxidized to carboxylic acids
- ketones resist oxidation
why do you need a acid (H+) catalyst for hydration reactions?
because water is a poor electrophile, in fact it is a nucleophile
Electrophilic carbons
- haloalkanes
- Alcohols
- Ethers
- Amines
nucleophilic carbons
- organometallic
what is an alkyl halide?
organic molecules containing a halogen atom bonded to an sp3 hybridized carbon atom
for haloalkanes what reactions do we expect to see?
substitution or elimination
what favours substitution?
-low temperatures
- small nucleophiles (attack the carbon inside the molecule)
- absence of steric hinderance (small H atoms around carbon centers)
what favours elimination?
- high temperature- larger nucleophiles (attack the hydrogen on the surface of the molecule)
- crowded carbon center ( bigger groups around carbon)
- any hinderance favours elimination
Alcohols
- require an H (acid) catalyst to drive the reaction forward
an alcohol can also undergo an oxidation reaction (also a type of elimination reaction) but an oxidant is required. What are they?
- K2Cr2O7: potassium dichromate
- KMnO4: potassium permanganate
- CrO3: chromium trioxide
- H2CrO4: chromic acid
- PCC : pyridinium chlorochromate
if the alcohol being oxidized is a 1° alcohol we will get…
- a carboxylic acid or
- aldehyde
if the alcohol being oxidized is a 2° alcohol then we get…
a ketone
if the alcohol being oxidized is a 3° alcohol then we get…
no reaction as they DO NOT OXIDIZE
are Ethers reactive or not?
not reactive as they are unusually stable
Amines
- basic and
- nucleophilic
Nucleophiles can either be neutral or be negatively charges. How do these react?
- neutral - requires an acid catalyst
- negatively charged - no catalyst required
nucleophilic addition
- a good nucleophile attacks first ( it will attack the carbon atom - the electrophile)
composite functional groups and the type of reaction they undergo?
- these all have the double bonded O
- carboxylic acids
- Esters
- Amides
- Acid chlorides
** These reactions undergo substitution
ketones are reduced to?
secondary alcohols
carboxylic acids are reduced to?
primary alcohols
aldehydes are reduced to?
primary alcohols
alkyl halides have what type of hybridization? (haloakanes)
sp3
Benzene? aromatic compounds do not undergo ______ reactions even though there are double bonds. Due to its stability it would rather undergo ______ reaction
addition
substitution
(electrophilic sub)
Halogenation of benzene
requires an acid catalyst like FeBr3 or AlCl3
Friedel crafts alkylation
Uses alkyl halides as reactants.
Friedel crafts acylation
Uses acyl halides as reactants, the double bonded oxygen with a Cl2
condensation polymerization
molecules are joined by the elimination of a small molecule (water)
addition polymerization
monomers must be an alkenea
acidic amino acids
have 2 carboxylic acid parts
basic amino acids
2 amine parts
non polar hydrophobis amino acids
has a benzene
polar hydrophilic amino acid
have OH groups
Aerosol
a colloid with a liquid/solid dispersed in a gas
- e.g fog, mist, smoke
Foam
colloid with a gas dispersed in a liquid/ solid
- e.g. whipped cream
gel
colloid with a solid dispered in a liquid
- e.g. clue, paint, blood, gelatin
emulsion
a liquid substance dissolved in a liquid medium where two immiscible liquids form a colloid held together by an emulsifying agent.
sol
when a solid substance is dispersed in a solid mediumamp
amphiphilic
contains both a hydrophobic tail and a hydrophilic head
conformational isomers
- single bonds
- free rotation around these bonds
- staggered (low energy) / eclipsed (high energy)
Geometric isomers
- require double/ triple bonds/ ring structures
- no rotation
-cis/ trans
enantiomers
- require sp3 hybridized carbons with 4 different substituents (chiral centers)
- NON SUPERIMPOSABLE MIRROR IMAGES
