Chemistry 102 Week 2 lecture

1
Chemistry 102Week 2 lecture

• Starting chapter 14
• Organic and Biochemistry for the Allied Health
  Fields
• Dr Mark Deming

2
Organic Chemistry Part II

• Compounds with O and N
  and sometimes S and P

3
Next few chapterscompounds with OXYGEN

• Alcohols Ethers
• Aldehydes Ketones
• Carboxylic acids Esters

1
CH 14
2
Connections to O
CH 17
More oxidized
3
CH 18
CH 19
4
4
Chapter 14(oxygen single bonded only)

• Alcohols C?O?H
• Phenols Ar?O?H (Araromatic
  or benzene ring)
• Ethers C?O?C
• Thiols C?S?H (and C?S?S?C)

5
(No Transcript)
6
(No Transcript)
7

• Alcohol has OH attached to aliphatic carbon
• Hydroxy group --OH functional group
• Phenol -OH attached to benzene
• Ether - has an oxygen between carbons

8
Naming of AlcoholsIUPAC

• 1. Name the longest chain to which a hydroxy
  group ( -OH) is attached and end in -ol
• 2. Number the longest chain to give the lowest
  number to the carbon with the hydroxy
• 3. Put location of hydroxy in front of root name
• 4. Locate and name any side groups in prefix

9
Nomenclature
10

• Naming Alcohols
• Step 1 Name the longest chain to which the OH
  group is attached. Use the alkane name of the
  chain, drop the e ending, and replace it with
  ol.
• Step 2 Number the longest chain to give the
  lowest number to the carbon with the OH.
• Step 3 Locate the OH position.
• Example

OH
CH3CH2CH2CHCH2CH3
6 5 4 3 2 1
3-hexanol
11

• Naming Alcohols, cont.
• Step 4 Locate and name any other groups
  attached to the longest chain.
• Step 5 Combine the name and location of other
  groups, the location of the OH, and the longest
  chain into the final name.
• Example

OH
CH3
CH3
CH3CH2CH2CHCHCH3
6 5 4 3 2 1
2,4-dimethyl-3-hexanol
12
Nomenclature

• Problem write the IUPAC name for each alcohol.

13
Nomenclature

• Solution

14

• .

15
Common Names for Alcohols

• The alkyl group name is followed by the word
  alcohol
• CH3OH methyl alcohol (IUPAC methanol)
• CH3CH2OH ethyl alcohol
• CH3CHCH3 isopropyl alcohol OH

16
VITAMIN B2 - Riboflavin
Stimulates health and growth of hair, nails, skin
cells. Helps eyes by bringing oxygen to body
tissues. Can help eliminate dandruff. May aid in
preventing hair loss.
Alcohol, poly functional, highly conjugated
14 atoms (16 atoms)
17
Riboflavin, Vitamin B2
Highly conjugated 14 atoms (16 atoms)
14 carbons conjugated becomes colorful
This compound is a pale yellow solid named
after latin flavis (yellow)
18

• Riboflavin is a water-soluble vitamin that was
  named from the Latin word flavius (yellow) to
  denote the deep color of crystals formed from the
  pure vitamin and the deep yellow color it gives
  to urine. Biochemically, riboflavin is
  metabolized to form the flavin coenzymes flavin
  adenine dinucleotide (FAD) and flavin
  mononucleotide (FMN). The functional moiety in
  both coenzymes is riboflavin's isoalloxazine ring
  system, which serves as a two-electron acceptor
  in enzymatic biochemical reductions. Enzymes that
  use a flavin cofactor are termed "flavoproteins"
  and have been extensively studied. Clinically,
  riboflavin promotes normal growth, helps with the
  breakdown of fat, and assists in the synthesis of
  steroids, red blood cells, and glycogen. Symptoms
  associated with riboflavin deficiency are
  inflammation of the tongue, light sensitivity,
  itching, dizziness, insomnia, and slow learning.
  In one open clinical study, high-dose riboflavin
  showed significant effectiveness as a migraine
  treatment. Common sources of riboflavin are
  almonds, yeast, cheese, eggs, chicken, beef,
  kidney, liver, and wheat germ. 
• Recommended Dietary Allowances Men 1.7 mg
  Women 1.3 mg Pregnant

19
Alcohols are broken into two main groups
Aliphatic and Aromatic
20
Aliphatic Alcohols

• They come in three types
• primary, secondary,
  tertiary
• This is based on how they react in reactions but
  does not affect naming
• Primary (1) only 1 carbon attached to carbon
  with OH
• KEY end of a chain, has 2 Hs on carbon
  attached
• Secondary (2) two carbons attached to carbon
  with OH
• KEY middle of chain, has 1 H on carbon attached
• Tertiary (3) three carbons attached to carbon
  with OH
• KEY middle of chain and NO Hs on carbon
  attached but it has an extra carbon attached to
  it.

21
Can You find all the types of OHs?
(primary, secondary, tertiary, aromatic)
1-aromatic 2-primary 3-aromatic 4-tertiary
5-secondary 6-primary 7-secondary 8-secondary
9-primary 10-aromatic 11-primary 12-tertiary
13-tertiary 14-secondary
Caution these molecules were made up and may not
be biologically relevant
22
Polar and Hydrogen Bonding

• We will focus today on the concept of
• Polarity
• Hydrogen bonding

23
Intermolecular Forces (between molecules)
Same force ? higher mass ? higher mp, higher
bp, lower vapor pressure
Same approx. mass ? higher force ? higher mp,
higher bp, lower vapor pressure
Energy of Attraction
(additive)
Energy of Disruption

• Ionicmust be an ionic compound (made of full
  charges)starts with metal or ammonium
  (acid-base salts)
• Super H-bondingH-bonding polar partially
  ionizescarboxylic acid COOH
• H-bonding
• from a O-H gt N-H to a lone pair on O gt
  NAmide (with H) gt alcohol (OH) gt amine (NH)
• Dipolar
• net polar moleculeester gt amide (no H) gt
  aldehyde gt ketone gt ether
• London Dispersion Forces (LDF)Non polar molecule
  (all molecules) aromatic gt -ynes gt -enes gt
  -anes (only C,H)

High TEMP(higher velocity)
gas
bp
Acid -CO2H
Low Mass (MW) High Vibration High
Velocity Starts with at given
temp.(same force) High
Mass (MW) Low Vibration Low Velocity
Has OH or NH
liquid
Increase Energy of Attraction
Increase Energy of Disruption
mp
Has O or N
solid
Low TEMP (lower velocity)
24
Polarity

• Polarity happens when an atom has an unequal pull
  on electrons
• H C N O P S
  Cl
• 2.1 2.4 3.0 3.5 2.1 2.4
  3.0
• The bigger the number below (electronegativity,
  EN) the more pull and if difference in EN is 0.4
  or less then nonpolar

25
Polarity cont.

• Example C O charge separation

d
d?
26
Physical Properties

• Alcohols are polar molecules
• The C-O and O-H bonds are both polar covalent.

27
IMF (Intermolecular Forces)alcohols and ether

• All molecules have LDF
• Polar if has O or N
• H-bonding if O-H or N-H to O or N
• Alcohols have LDF and are polar and can both give
  and receive an H-bond
• Ethers are polar but can only receive an H-bond

receive
give
28
Hydrogen Bond

• A special connection between molecules
• One molecule must give an H-bond and one molecule
  must take an H-bond
• To give an H-bond the molecule must have an O-H
  or an N-H bond (NOT C-H)
• To take an H-bond the molecule must have and O or
  N with three or less connections (at least one
  lone pair)

29
Alcohol to Water bonding
Receive H-bond
Receive H-bond
Give H-bond
Give H-bond
30
Polar H-bondingHydrophilic
Alkane likeNon PolarHydrophobic
Important Expected to know Rule of thumb
Each OH can make soluble 3
carbons
31
more soluble
Solubility of alcohols in water
Soluble-one layer
insoluble-two layers
less soluble
Four carbons is at the edge of visual solubility
not soluble
Remember that solubility means dissolve in (or
mix with) another chemical
Fig. 13-2, p.419
32
Physical Properties of pure alcohols

• In the liquid state, alcohols associate to each
  other by hydrogen bonding.

33
Alcohol to alcohol bonding
34
Note C3 and C2O are about the same weight, both
have 3 big atoms near each other in the
table. Difference must be type of IMF.
C4O
C2O
C5
C3
35
Physical Properties

• bp increases as MW increases.
• Solubility in water decreases as MW increases.

36
Acidity of Alcohols

• Alcohols have about the same pKa values as water
  aqueous solutions of alcohols have the same pH as
  that of pure water.
• Alcohols and phenols both contain an OH group.
• Phenols are weak acids and react with NaOH and
  other strong bases to form water-soluble salts.
• Alcohols are not acids and do not react in this
  manner.

37
REACTIONS of Alcohols

• In this chapter you are responsible for
• Elimination Reactions
• To form alkenes (a type of reduction)
• To form ethers (neutral )
• Oxidation Reactions
• Of primary and secondary alcohols
• Tertiary and aromatic unreactive to oxidation

Note other alcohol reactions we
will see in future chaptersChapter 16- aldehydes
and ketones react with alcohols to form acetals
and ketalsChapter 17- carboxylic acids react
with alcohols to become esters
38
(No Transcript)
39
Reactions of Alcohols
CO2 H2O
EthersNOT REACTIVE
Alcohol
excess O2
? Combustion ?
C H2O or CO H2O
limited O2
Dehydration(H, Reduction) ( losing H20 )
O
Oxidation Ooxidizing agent
180ºC
140ºC
end
middle
Alkene
Ether
If primary (1º)
If secondary (2º)
If tertiary (3º)
Aldehyde
Ketone
No Reaction
Carboxylic Acid
O
40
Reactions of Alcohols
Dehydration of alcohols to give ethers
Dehydration of alcohols to give alkenes
H- Reduction
Low concentration
High concentration
Oxidation of Primary (1º) alcohol
Oxidation of secondary (2º) alcohol
Oxidation of Tertiary (3º) alcohol NO REACTION
NADA NOTHING NO WAY
41
Alcohol Reactions- Elimination

• Elimination Reaction -remove a molecule
• Dehydration to form a double bond
• Elimination of H2O to form double bond
• Dehydration to form an ether
• Elimination of H2O to from 2 alcohols form an
  ether

42
Elimination Reactions of Alcohol (cont)

• Elimination Reaction of an Alcohol
• to form alkenes
• The removal of water (dehydration) from an
  alcohol is an elimination reaction and produces
  an alkene.

Strong Acid Catalyst
The alcohol is usually in low concentrations to
avoid ether formation
43
Elimination Reactions of Alcohol (cont)

• Dehydration to form Ethers.
• Under slightly different conditions, a
  dehydration reaction can occur between two
  alcohol molecules to produce an ether.

The alcohol is usually in high concentration and
lower temperature to avoid alkene formation
44
Reactions of Alcohols- Oxidation

• Official Definitions (chem 102 does not use)
• Oxidation is really the losing of electrons at an
  atom by formal electron counting
• Reduction is the gaining of the electrons at an
  atom
• Practical Usage in this class At a CARBON

H
O
OXIDATION REDUCTION
Gain of connections to oxygen (gain Os) Loss of connections to oxygen (lose Os)
Lose hydrogens(lose Hs) Gain hydrogens(gain Hs)
45
Reactions of Alcohols- Oxidation

• Remember that Oxidation
• Is the gain of oxygens or the loss of hydrogens
  at a carbon.
• Usually done with a chemical that will itself get
  reduced called an oxidizing agent and we will
  abbreviate it with O

46
Reactions of Alcohols- Oxidation

• Oxidation of Aliphatic Alcohols
• Primary alcohols ? aldehyde ? carboxylic acid.
• Secondary alcohols ? ketone.
• Tertiary alcohols ? no reaction.
• Oxidation of Aromatic Alcohols
• No reaction- not easily oxidized

47

• Alcohol Reactions, cont.
• Primary alcohol oxidation
• Secondary alcohol oxidation

Note most strong oxidizing agents will make the
reaction go all the way to the carboxylic acid
48
Potassium ChromateK2Cr2O4 (The oxidizing agent)
Ethanol
These are the reactants
Fig. 13-7a, p.423
49
Ethanol is oxidized to acetic acid Chromate is
reduced (green-grey)
When mixed the products are in the second tube
Fig. 13-7b, p.423
50
Important Alcohols

• Methanol
• Ethanol
• Isopropyl alcohol
• Glycerol
• Aromatic alcohols
• Phenol, BHA, BHT

51
Important Alcohols (cont.)

• Methanol (wood alcohol) CH3OH.
• Production
• Useful as a solvent and industrial starting
  material.
• Highly toxic, causes blindness and/or death.

52
Important Alcohols (cont.)

• Ethanol (ethyl alcohol, grain alcohol, drinking
  alcohol)
• Useful as a solvent, industrial starting
  material, fuel (gasohol), and found in alcoholic
  beverages. Moderately toxic.

Production
NON RENEWABLEFrom etheylene
RENEWABLEfermentation of carbohydrates (corn) by
yeast (biological)
53
Important Alcohols (cont.)

• 2-propanol (isopropyl alcohol) is the main
  component of rubbing alcohol.
• 1,2,3-propanetriol (glycerol, glycerin) is used
  as a food moistening agent (nontoxic) and for its
  soothing qualities (soaps).

54
Important Alcohols (cont.)

• Antifreezes1,2-ethanediol (ethylene glycol).
• 1,2-propanediol (propylene glycol).

Dont need to know for test
55
Important Alcohols (cont.)

• Phenols and their uses
• In a dilute solution, phenol is a disinfectant.
• Phenol derivatives used as disinfectants
• o-phenylphenol
• 2-benzyl-4-chlorophenol
• Phenol derivatives used as antioxidants in food
• BHT (butylated hydroxy toluene)
• BHA (butylated hydroxy anisole)

56

• Phenol is a medical antiseptic first used by
  Joseph Lister in 1867. Lister showed that the
  occurrence of postoperative infection
  dramatically decreased when phenol was used to
  cleanse the operating room and the patients
  skin.
• The medical use of phenol is now restricted
  because it can cause burns and is toxic. Only
  solutions with lt1.5 phenol or lozenges with lt50
  mg of phenol are now allowed in nonprescription
  drugs. Many mouthwashes and throat lozenges
  contain alkyl-substituted phenols such as thymol
  as active ingredients for pain relief.
• Alkyl-phenols such as the cresols are common as
  disinfectants in hospitals. Antiseptics safely
  kill microorganisms on living tissue,
  disinfectants should only be used on inanimate
  objects.

57
Ethers Official Naming

• Ethers There is NO ending name
• Naming ethers the O-R group is called an
  alkoxy group. The yl ending of the smaller R
  group is replaced by oxy.
• The smallest group attached to O is named as an
  alkoxy side group with the O

OXYto smallest group
58
Ethers Common Names

• The Common naming of simple ethers is in some
  places preferred and are widely used.
• Common Names of Ethers. Name each group
  attached to the O as a side group and attach
  ether as a separate word to the end.

59

• Cyclic Ethers
• Heterocyclic rings contain atoms other than
  carbon in the ring.

THFTetrahydrofuran
60
Properties of Ethers

• Properties of Ethers
• Much less polar than alcohols.
• More soluble in water than alkanes, but less
  soluble than alcohols.
• Low boiling and melting points because of the
  inability to hydrogen bond between molecules.

61

• Hydrogen bonding of dimethyl ether (a) with
  water and (b) no hydrogen bonding in the pure
  state

62

• Ether Reactions
• Like alkanes, ethers are inert and do not react
  with most reagents.
• Also like alkanes, they are highly flammable.

63
Thiols

• Thiols the SH (sulfhydryl, mercaptan) group
• Most distinguishing characteristic is their
  strong and offensive odor.
• Ethanethiol added to natural gas.
• 1-propanethiol odor in garlic and onions.
• Trans-2-butene-1-thiol odor associated with
  skunks.

64
Sulfur Reactions
O (oxidation) -- (lose Hs as water)
Thiols 2 R?S?H
Disulfide linkage R?S?S?R Found in proteins,
enzymes and hair to retain specific shape
H (Reduction)
M Hg2 or Pb2
Hg2 or Pb2
Accumulates over lifetime Dimethyl mercury is
nonpolar and will reside in fatty tissues and
lymphatic system and cell walls. It is slowly
released doing damage. Children affected more!
Metal Sulfides R?S?M?S?R Distorts shape of
proteins, enzymes making them inactive. Retained
in hair
65

• Thiol Reactions
• Oxidation forms disulfide (-S-S-) linkages which
  are important structural features of some
  proteins.

66

• Thiol Reactions, cont.
• Reacts with heavy metals (Pb2, Hg2) to form
  insoluble compounds, with adverse biological
  results. This is why lead and mercury are always
  in the news as pollutants.
• Why is this so bad?

67
Six Chemical Connectors in Biology

• These will connect (bond) Biological units
  together and are energetically easy to undo.

Thischapter

• Disulfide Linkage
• Glycosidic Linkage (acetal, ketal linkage)
• Ester Linkage (universal connector)
• Amide Linkage
• Phosphate Ester Linkage
• Amino Glycosidic Linkage (DNA, ATP)variation of
  2

Ch 17
Ch 19
Ch 19
Ch 17
Implied from Ch 16 and Ch 15
Note We can make these connections in a test
tube but biologically there is an enzyme to make
and break each connector above.
68
3 Binders used in Biological systems
These hold pieces or parts together but not
bonded, Easier to break
Ch 16,18

• Salt bridges amines () to acids (-)
• H-bonding
• OH to O strong ( starches, alpha helix, beta
  sheet)
• OH to N medium
• NH to O medium (DNA)
• NH to N weak (DNA)
• Nonpolar to Nonpolar (many times also used to
  exclude water)
• Long straight chains (lots of overlap) waxes,
  cell memb.
• Aromatic ring stacking

Thischapt
Ch 12
Ch 13
69

• Polyfunctional Compounds
• Compounds with two or more functional groups.
  Functional groups determine chemical properties
  of compounds.
• Example

70
More examples of finding functional groups in
polyfunctional compounds

• Are found in the handout titled Finding
  Function Groups Practice
• It covers groups from Chapters 11-19