categories of organic reactions There are so many types of organic reactions. We’re going to focus on just a few. There are so many types of organic reactions. We’re going to focus on just a few.  Addition Reactions  Substitution Reactions  Elimination Reactions  Oxidation – Reduction Reaction

Bond Breaking: Polar and Non-polar

Bond Forming: Polar and Non-polar

I- Addition Reactions In alkenes and alkynes In addition reactions, reactants are added to the carbon atoms in the double or triple bond.In addition reactions, reactants are added to the carbon atoms in the double or triple bond. The double or triple bond is easily broken, since it is highly reactive.The double or triple bond is easily broken, since it is highly reactive.

In hydrogenation, Hydrogen atoms add to the carbon atoms of a double bond or triple bond.Hydrogen atoms add to the carbon atoms of a double bond or triple bond. converts unsaturated molecule to saturatedconverts unsaturated molecule to saturated alkene or alkyne + H 2 → alkanealkene or alkyne + H 2 → alkane A catalyst such as Pt or Ni is used to speed up the reaction.A catalyst such as Pt or Ni is used to speed up the reaction. Unsaturated vegetable oils reduced to produce saturated fats used in margarine and cooking products Unsaturated vegetable oils reduced to produce saturated fats used in margarine and cooking products 1- Hydrogenation (addition of Hydrogen)

2- Hydration (addition of water H2O) an acid H + catalyst is required.an acid H + catalyst is required. water (HOH) adds to a double bond.water (HOH) adds to a double bond. an H atom bonds to one C in the double bond.an H atom bonds to one C in the double bond. an OH bonds to the other C.an OH bonds to the other C. H OH H OH H + │ │ H + │ │ CH 3 ─ CH=CH ─ CH 3 + H ─ OH CH 3 ─ CH ─ CH ─ CH 3

Hydration When hydration occurs with a double bond that has an unequal number of H atoms, thethe H atom bonds to the C in the double bond with the more H. OH bonds to the C in the double bond with the fewer H atoms. OH OH H H + H + ││ CH 3 ─ CH=CH 2 CH 3 ─ CH=CH 2 + H ─ OH H ─ OH CH 3 ─ CH ─ CH 2

3- Halogenation In Halogenation, halogen atoms add to the carbon atoms of double bond or triple bond. halogen atoms add to the carbon atoms of double bond or triple bond. Addition of Br 2 and Cl 2 to alkenes to yield 1,2- dihalides Addition of Br 2 and Cl 2 to alkenes to yield 1,2- dihalides

A color test for c=c Bond

Halogenation

4- Hydrohalogenation In hydrohalogenation, the atoms of a hydrogen halide add to the carbon atoms of a double bond or triple bond. the atoms of a hydrogen halide add to the carbon atoms of a double bond or triple bond.

Markovnikov’s Rule In the addition of HX, H 2 O, H 2 O, or ROH to an alkene, H adds to the carbon of the double bond having the greater number of hydrogens.

II- Substitution Reactions Are characteristic reaction of saturated compounds such as alkanes. In a substitution reaction, one atom, ion or group is replaced (substituted) by another CH 4 + Cl 2 CH 3 Cl + HCl CH 3 Cl + Cl 2 CH 2 Cl 2 + HCl CH 2 Cl 2 + Cl 2 CHCl 3 + HCl CHCl 3 + Cl 2 CCl 4 + HCl

Needs ultraviolet light to initiate the reaction.

Nucleophilic Substitution Reactions Each step involves the substitution of one nucleophile (chloride ion, Cl -, or hydroxide ion, HO - ) by another Each step involves the substitution of one nucleophile (chloride ion, Cl -, or hydroxide ion, HO - ) by another Nucleophile: a molecule or ion that donates a pair of electrons to another molecule or ion to form a new covalent bond To be a good leaving group the substituent must be able to leave as a relatively stable, weakly basic molecule or ion In alkyl halides the leaving group is the halogen substituent- it leaves as a halide ion Because halide ions are relatively stable and very weak bases, they are good leaving groups Substitution of alkyl halides with nuclophiles can occur by an S N 2 or S N 1 path, a fundamental difference between them is the timing of bond breaking and bond forming steps

III- Elimination Reactions Elimination: removal of atoms or group of atoms from adjacent carbon to form a carbon-carbon double bond Elimination: removal of atoms or group of atoms from adjacent carbon to form a carbon-carbon double bond These are the opposite of additions These are the opposite of additions This used to prepare alkenes This used to prepare alkenes An important elimination reaction is Dehydrohalogenation An important elimination reaction is Dehydrohalogenation

Dehydrohalogenation (-HX)