CHM 219 Module 5
Alcohol - answerGeneric formula R-OH, defined by the presence of a Hydroxyl group (-
OH). Organic derivatives of water, as one of the hydrogen atoms from the water
molecule is replaced by an alkyl group.
Phenols - answerHydroxyl group directly attached to a benzene ring
Methyl Alcohol - answerOnly H atoms attached to the carbon bearing the-OH group
Primary Alcohol - answerone alkyl group attached to the carbon atom bonded to the -
OH group
Secondary Alcohol - answerTwo alkyl groups attached to the carbon atom bonded to
the -OH group
Tertiary Alcohol - answerThree alkyl groups attached to the carbon atom bonded to the
-OH group
Boiling Point of Alcohols - answerHigh due to Hydrogen bonding between the positively
charged H and negatively charged O
Water solubility of alcohols - answerAs the carbon chain length increases alcohol
becomes correspondingly less soluble in water.
Alcohols Acidity/Basicity - answerCan act as a weak base (accepting H+ using a lone
pair on the O atom) or weak acid (donating the O-H proton as H+)
Amphoteric - answera substance that can act as both an acid and a base
Alkoxide Ion - answerconjugate base of an alcohol, very strong base
Alkyloxonium Ion - answerThe conjugate acid of the alcohol is often called a protonated
alcohol,
Dehydration - answerLoss of water. An alcohol molecule will lose H2O to form an
ALKENE. Type of elimination reaction — lose the -OH from one C and H atom from the
adjacent C.
First step — alcohol acts as a base.
Tertiary alcohols - E1
Primary alcohols - E2
All dehydration begins with... - answerProtonation of the alcohol group.
, Order of ease of dehydration of alcohol substrates... - answer3>2>1
Tertiary require the least harsh conditions (typically 25% aqueous acid and 60-80
degrees C) whereas primary require fully concentrated acid and temperatures
approaching 200 degrees C.
If more than one alkene product is possible... - answerThe major product is the one
whose C=C has more alkyl groups attached.
ZAitsev's Rule - answerThe production of the more highly substituted alkene as the
major product.
Alcohols —> Alkyl Halides - answer-Substitution REaction , replacing the -OH with a
halogen
-Alcohol (R-OH) + Hydrogen Halide (H-X) ——> alkyl halide (R-X) + water (H-OH)
-the use of Hydrogen halides promotes the substitution in two ways
1. Acid protonates the -OH of the alcohol to make it a good leaving group
2. Halide ions are good nucleophiles but weak bases so substitution is promoted over
elimination
Order of Reactivity of Alcohols with HX - answer3>2>1
Primary Alcohols react via.... (With HX) - answerSn2
-OH group is protonated and then displaced as a water molecule by a chloride ion
Secondary Alcohols react via... (with HX) - answerSn1 or Sn2 - depending on the
structure of the specific alcohol
Conversion using Phosphorous Halides (PX3) - answerX= Cl or Br
- Alcohol (3R-OH) + phosphorous trihalide (X2P-X) —> alkyl halide (3R-X) + H3PO3
-particularly efficient as one molecule of PX3 can convert 3 molecules of alcohol to the
corresponding alkyl halide
-byproduct of the reaction is phosphorous acid
Conversion using Thionyl Chloride (SOCl2) - answerAlcohol (R-OH) + Thionyl Chloride
(Cl-S=O-Cl) —> alkyl Chloride (R-Cl) + SO2 ^ + HCl
- very efficient with primary and secondary alcohols d/t the main byproduct (SO2) beig
formed as a gas and leaving the reaction mixture.
Oxidation to Aldehydes, Ketones and CArboxylic Acids - answerOxidation - increasing
the oxygen content (number of oxygen atoms) or the oxygen character (more bonds to
oxygen)
-Primary Alcohols —> aldehydes —> Carboxylic Acids
-SEcondary Alcohols —>ketones
-Tertiary - unreactive
Alcohol - answerGeneric formula R-OH, defined by the presence of a Hydroxyl group (-
OH). Organic derivatives of water, as one of the hydrogen atoms from the water
molecule is replaced by an alkyl group.
Phenols - answerHydroxyl group directly attached to a benzene ring
Methyl Alcohol - answerOnly H atoms attached to the carbon bearing the-OH group
Primary Alcohol - answerone alkyl group attached to the carbon atom bonded to the -
OH group
Secondary Alcohol - answerTwo alkyl groups attached to the carbon atom bonded to
the -OH group
Tertiary Alcohol - answerThree alkyl groups attached to the carbon atom bonded to the
-OH group
Boiling Point of Alcohols - answerHigh due to Hydrogen bonding between the positively
charged H and negatively charged O
Water solubility of alcohols - answerAs the carbon chain length increases alcohol
becomes correspondingly less soluble in water.
Alcohols Acidity/Basicity - answerCan act as a weak base (accepting H+ using a lone
pair on the O atom) or weak acid (donating the O-H proton as H+)
Amphoteric - answera substance that can act as both an acid and a base
Alkoxide Ion - answerconjugate base of an alcohol, very strong base
Alkyloxonium Ion - answerThe conjugate acid of the alcohol is often called a protonated
alcohol,
Dehydration - answerLoss of water. An alcohol molecule will lose H2O to form an
ALKENE. Type of elimination reaction — lose the -OH from one C and H atom from the
adjacent C.
First step — alcohol acts as a base.
Tertiary alcohols - E1
Primary alcohols - E2
All dehydration begins with... - answerProtonation of the alcohol group.
, Order of ease of dehydration of alcohol substrates... - answer3>2>1
Tertiary require the least harsh conditions (typically 25% aqueous acid and 60-80
degrees C) whereas primary require fully concentrated acid and temperatures
approaching 200 degrees C.
If more than one alkene product is possible... - answerThe major product is the one
whose C=C has more alkyl groups attached.
ZAitsev's Rule - answerThe production of the more highly substituted alkene as the
major product.
Alcohols —> Alkyl Halides - answer-Substitution REaction , replacing the -OH with a
halogen
-Alcohol (R-OH) + Hydrogen Halide (H-X) ——> alkyl halide (R-X) + water (H-OH)
-the use of Hydrogen halides promotes the substitution in two ways
1. Acid protonates the -OH of the alcohol to make it a good leaving group
2. Halide ions are good nucleophiles but weak bases so substitution is promoted over
elimination
Order of Reactivity of Alcohols with HX - answer3>2>1
Primary Alcohols react via.... (With HX) - answerSn2
-OH group is protonated and then displaced as a water molecule by a chloride ion
Secondary Alcohols react via... (with HX) - answerSn1 or Sn2 - depending on the
structure of the specific alcohol
Conversion using Phosphorous Halides (PX3) - answerX= Cl or Br
- Alcohol (3R-OH) + phosphorous trihalide (X2P-X) —> alkyl halide (3R-X) + H3PO3
-particularly efficient as one molecule of PX3 can convert 3 molecules of alcohol to the
corresponding alkyl halide
-byproduct of the reaction is phosphorous acid
Conversion using Thionyl Chloride (SOCl2) - answerAlcohol (R-OH) + Thionyl Chloride
(Cl-S=O-Cl) —> alkyl Chloride (R-Cl) + SO2 ^ + HCl
- very efficient with primary and secondary alcohols d/t the main byproduct (SO2) beig
formed as a gas and leaving the reaction mixture.
Oxidation to Aldehydes, Ketones and CArboxylic Acids - answerOxidation - increasing
the oxygen content (number of oxygen atoms) or the oxygen character (more bonds to
oxygen)
-Primary Alcohols —> aldehydes —> Carboxylic Acids
-SEcondary Alcohols —>ketones
-Tertiary - unreactive
