PIGMENTS, PERFUMES AND POISONS

1
Question of the day What is the
structural formula of butane (C4H10)? (Butane
gas)
2
Today

• Chemical reactions
• Structures of organic molecules
• Hydrocarbons

3
Chemical Reactions in General

• Bonds between atoms are broken and new
  combinations of atoms are bonded together
• Energy is required.
• At higher temperatures chemical reactions
  proceed faster.
• Meaning of Endothermic or exothermic
  reaction?
• Signs that a chemical reaction probably has
  occurred? .
• 
  EXPERIMENT!

4
Chemical Reactions in Plants Time and highly
specialized catalysts .
5
Photosynthesis
Glucose
required for the biosynthesis of cellulose,
plant pigments, fragrances, plant toxins ..
A very general equation !
6
Organic compounds (in Plants) Review/preview
your reader for good understanding
7

• Practice
• Organic compound or not ?
• H2O b) C6H12O6
• c) C12 H22O11 d) CH4
• e) CO2 f) C (carbon) g) CaCO3?

8
Structures of Organic Molecules

• Organic molecules are made up of only a few
  elements
• C (4 bonds)
• H (1 bond)
• O (2 bond)
• N (3 bonds)

9
Hydrocarbons (have C, H only)
Introduction to organic molecules
H
H
C
H
H
CH4 methane Natural gas Cooking gas In swamps
10
Hydrocarbons
H
C2H6 ethane C3H8 propane C4H10 butane C7H16
heptane C8H18 octane C10H22 decane
H
C
Gases at RT!
H
H
CH4 methane
Liquids at RT!
More than about 16 Cs Solid at RT
11
Isomers Same molecular formula, different
structures
Draw isomers for C5H12 (pentane)
12
Gas chromatogram of a petroleum sample
13
Resin of Jeffrey Pines contains Heptane C7H16
14
Fragrance of Magnolias contains Decane C10H22
15
Ethylene (Ethene), a ripening hormone
16
Example Combustion of C6H14 (hexane found in
gasoline) C6H14 O2 CO2 H2O
E!Balanced equation 2 C6H14 19 O2
12 CO2 14 H2O
Combustion Burning
Complete combustion of an organic compound, i.e.
with plenty of oxygen, always forms the products
CO2 and H2O
17
A picture to think about .
18
Next time

• Getting energy
• Glucose and other organic molecules