14. Alcohols, Ethers, Thiols

Question 1

Tinctures

Answer 1

Solutions in which ethanol is the solvent

Question 2

Alcohol

Answer 2

-functional group —OH (hydroxyl) group
-bonded to tetrahedral carbon atom
-Classified depending on number of carbon groups bonded to carbon bearing —OH group
•Primary (1°)
•Secondary (2°)
•Tertiary (3°)

Question 3

IUPAC naming
ALCOHOL

Answer 3

1. Longest carbon chain containing —OH group as parent alkane;
   Number to give hydroxyl group lowest possible;
   Hydroxyl group takes precedence over alkyl group, aryl group, halogens
2. Ending of parent alkane from -e to -ol; Use number to locate —OH group; For cyclic alcohol, numbering starts at —OH group
   (i.e. ,1-Butanol, cyclohexanol)
3. Diol, triol, etc… depending on the number of —OH group;
   Final -e in parent alkane is retained when using these (1,2-ethanediol)

Question 4

Common name
Alcohol

Answer 4

1. Name alkyl group bonded to —OH and add the word alcohol
   (Isobutyl alcohol, tert-Butyl alcohol, Cyclohexanol alcohol)
2. Compounds containing two —OH group on adjacents on adjacent carbon atoms (GLYCOLS)
   (i.e. ethylene glycol, propylene glycol)

Question 5

Glycerin/ Glycerol

Answer 5

1,2,3-Propanetriol

Glycerin + HNO3 ➡️ 1,2,3-Propanetriol trinitrate (nitroglycerin) + H2O

Question 6

Dynamite

Answer 6

-mixture of nitroglycerin, diatomaceous earth, sodium carbonate
-Albert Nobel

Question 7

Polarity of alcohols

Answer 7

—OH group
-large electronegativity difference between C-O and O-H
-polar covalent
-higher boiling point than alkanes, alkenes and alkynes of similar molecular weight (due to hydrogen bonding)

Question 8

⬆️ Molecular weight ⬆️ Boiling point

Question 9

Solubility of alcohol in water

Answer 9

⬆️ Molecular weight
⬇️ Water solubility
due to increase of hydrocarbon portion (decreases water solubility) of the alcohol

Question 10

Acidity of alcohol

Answer 10

-about same pKa as water

Question 11

Acid-catalyzed dehydration alkenes

Answer 11

-elimination of water molecule of water from an alcohol. OH is removed from one carbon and H from adjacent carbon

Ethanol ➡️ Ethylene (alkene) + H2O
-heating with 85% phosphoric acid or concentrated sulfuric acid

-primary alcohols: most difficult to dehydrate (high temp)
-when isomeric alkenes yield, alkene with greater number of alkyl groups on double bond predominates

Question 12

Oxidation of primary and secondary alcohol

Answer 12

Primary alcohol oxidizes to:
➡️ Aldehyde ➡️ Carboxylic acid
-reagent most commonly used for oxidation of alcohol to carboxylic acid is potassium dichromate (K2Cr2O7) dissolved in aqueous sulfuric acid

Secondary alcohols oxidizes to
➡️ Ketones
-reagent used potassium dichromate (K2Cr2O7)

Tertiary alcohols RESIST OXIDATION
-carbon bearing —OH is bonded to 3 C so it cannot form CO double bond

Question 13

Ether

Answer 13

-compound containing oxygen atom bonded to 2 carbon atoms
-tetrahedral angle (at O)

Question 14

IUPAC naming
ETHERS

Answer 14

(For complex ethers)

1. Name the simpler alkyl group + O atom as an ALKOXY SUBSTITUENT by changing -yl to -oxy
2. Name the remaining alkyl group as ALKANE with the alkoxy group as susbtituent
   (i.e. 4-ethoxyoctane)

Question 15

Common name
Ethers

Answer 15

(For simple ethers)

1. Name both alkyl groups bonded to oxygen; arrange alphabetically
2. Add word ether
3. For symmetrical ethers, name alkyl group then add di-

Question 16

Cyclic ethers

Answer 16

-an ether in which ether oxygen is one of the atoms of a ring
-known by common names
(i.e. ethylene oxide, tetrahydrofuran)

Question 17

Heterocycle

Answer 17

-any cyclic compound containing heteroatom (atom other than C)

Question 18

Physical properties
Ethers

Answer 18

-polar compounds
-only weak forces of attraction exist between ether molecules in pure liquid
-boiling point of ethere is close to hydrocarbons of similar weight
-more soluble in water than hydrocarbons of similar molecular weight and shape

Question 19

Reaction of Ethers

Answer 19

-resemble hydrocarbons in their resistance to chemical reaction
-do not react with oxidizing agents (K2Cr2O7)
-do not react with reducing agents (H2)
-good solvent properties for organic reactions (diethyl ether, tetrahydrofuran)

Question 20

Laughing gas

Answer 20

N2O2
-Nitrous oxide
-colorless gas
-isolated by Joseph Priestly (1772)

-Sir Humphry Davy (1799) demonstrated compound’s anesthetic effect (laughing gas)

-di naging effective laughing gas sa dental practice

-Charles Jackson: anesthesized himself using DIETHYL ETHER; eventually nagamit sa surgery

Question 21

Thiols

Answer 21

-compound containing —SH (sulfhydryl) group bonded to tetrahedral carbon atom
-parang alcohol structure pero -SH imbes -OH

-stench (low molecular weight thiols)
-skunk, rotten eggs, sewage

Question 22

Mercaptan

Answer 22

-common name for any molecule containing -SH group
-“mercury capturing”
-thiols react with Hg2+ in aqueous solution to give sulfide salts as insoluble precipitates
-i.e. C6H5SH + Hg2+ ➡️ (C6H5SH)2Hg

Question 23

Physical properties of Thiols

Answer 23

-nonpolar covalent
-lower boiling pt. and less soluble in water than alcohols of similar structure

Question 24

Disulfide

Answer 24

Compound containing —S—S—- group

Question 25

Reactions of Thiols

Answer 25

-weak acids comparable in strength to phenols
-react with strong bases to form thiolate salts
-most common reaction in biological systems is oxidation to disulfides

Question 26

Wood alcohol

Answer 26

-methanol
-derived from heating hard wood in limited supply of air

Question 27

Ethylene glycol

Answer 27

-major component in automobile antifreeze

Question 28

Isopropyl alcohol

Answer 28

-rubbing alcohol, hand lotions, after-shave lotion etc

Question 29

Glycerin

Answer 29

-by product of the manufacture of soaps by saponification of animal fats and tropical oils