reactions of hydrocarbons: combustion

Reactions of Hydrocarbons: Combustion

2 CH3CH2CH2CH3(g) + 13 O2(g) → 8 CO2(g) + 10 H2O(g)

CH3CH=CHCH3(g) + 6 O2(g) → 4 CO2(g) + 4 H2O(g)

2 CH3CCCH3(g) + 11 O2(g) → 8 CO2(g) + 6 H2O(g)

Anything that contains carbon and hydrogen (and often other elements)

Reactions of Alkanes: Substitution

CH3CH3 + Br2 ® CH3CH2Br + HBrlight

CH3CH2CH2CH3 + Br2 → many productslight

Hydrogenation: addition of H2 (with metal catalyst: Pt, Pd, Ni)

CH2=CHCH3 + Br2 ® CH2BrCHBrCH3

CH2=CHCH3 + H2 ® CH3CH2CH3Pt

Halogenation: addition of X2 (Cl2, Br2, I2)

Alkene/alkyne addition reactions

+ H2 ® Pd

Hydrohalogenation (addition of HX, X = F, Cl, Br, or I)

CH2=CHCH3 + HBr ® CH3CHBrCH3

+ H2O ®

Hydration (addition of H2O, or H + OH)

Markovnikov addition: “The rich get richer” Carbon that starts with more hydrogens gets the additional hydrogen(s)

+ 2HBr ® Br Br

OH

H+

Alkene/alkyne addition reactions, cont.

Oxidation of alkenes

KMnO4 (aq)

Cold, dilute

OH

OH

In organic chemistry: Oxidation: carbon adds oxygen and/or loses hydrogenReduction: carbon loses oxygen and/or adds hydrogen

also an addition reaction

KMnO4 (aq)

Hot, concentrated

Oxidation of alkenes, cont.

O

OH

O+

KMnO4 (aq)

Hot, concentrated

OH

O

O

Reactions of aromatic compounds

Substitution:Halogenation (with Cl2 or Br2 and Fe catalyst)

Cl

Fe + HCl+ Cl2

Oxidation (of alkyl benzene at the first alkyl carbon)

Reactions of aromatic compounds, cont.

COOH

KMnO4 (aq)

hot, conc.

Reactions with Alcohols

Elimination (backwards of addition) e.g. Dehydration

HOH2SO4

HOH2SO4 No reaction

Reactions with Alcohols, cont.

• Oxidation 1° alcohols aldehydes, carboxylic acids2° alcohols ketones3° alcohols NO REACTION

HO

KMnO4 (aq)

HO

O

OH

KMnO4 (aq)

O

OH KMnO4 (aq)

No reaction

KMnO4 (aq)

No reactionAlso note:

Reactions with Alcohols, cont.

• Reduction (for 1°, 2° or 3°)

2 HO-R + 2 Na 2 NaOR + H2 (g)

recall: 2 Na + 2 H2O 2 NaOH + H2 (g)

Phenol as an acid

+ NaOH

ONa

+ H2O

Strong baseWeak acid

Acid/base reaction

Reactions of Aldehydes and Ketones

Oxidation of aldehydes to carboxylic acids:

RCHO RCOOHKMnO4 (aq)

O

KMnO4 (aq)

O

HO

Reactions of Aldehydes and Ketones, cont.Reduction of aldehydes and ketones to alcohols primary and secondary alcohols

Several possible catalysts, a few examples:

O OH+ H2

Ni

O OH+ H2

Pd

Reactions of carboxylic acids

Acid/base reactions:

sodiumacetate

sodium pentanaote

HO

O+ NaOH

NaO

O+ H2O

HO

O+ NaOH

NaO

O+ H2O

acetic acid

Esterification:

Reactions of carboxylic acids, cont.

Amine Reactions

• Amines are weak organic bases.– Will react with strong acids to form ammonium

saltsRNH2 + HCl → RNH3

+Cl−

(recall: NH3 + HCl → NH4+Cl− )

When they react with carboxylic acids in a condensation reaction, an amide is produced.

OH

O

R + NHR3 NR2

O

R + H2OHeat

OH

O+ CH3NH2 NHCH3

O+ H2O

Heat

OH

O+ NH3 NH2

O+ H2O

Heat

Amide formation from reaction of primary or secondary amines or ammonia with carboxylic acid:

1° amine 2° amide

1° amideammonia

Amine Reactions, cont.

Hydrolysis of esters and amides

OH

O+ CH3NH2

NHCH3

O+ H2O

H+ (aq)

O-K+

O+ CH3NH2NHCH3

O+ KOH(aq)

OH

O+ CH3CH2OHO

O

+ H2OH+ (aq)

Water (with acid or base) breaks the ester and amide linkages.