Functional derivatives of carboxylic acids
= functional carboxyl group is changed
2.1. SALTS
Basic Chemistry XII
Vladimíra Kvasnicová
R―COO- M+ (M+ = metal cation)
= products of neutralization
(acid + base → salt + water)
• suffix: -ate or -oate
-ic acid → -ate
/ -oic acid → -oate
• R―COO- = carboxylate (anion of c.a.)
• full name: cation carboxylate
(sodium acetate)
2.2. ESTERS
R1―O―CO―R2
= products of esterification
(acid + alcohol → ester + water)
Examples of esters
• ethyl formate = ethyl methanoate
• the opposite reaction = ester hydrolysis
• methyl butyrate
• suffix: -ate
some esters have a fruity smell:
• R1―O― = rest of alcohol
• CH3-CH2-CH2-CO-O-CH3 (apple)
• R1 = alkyl (from the alcohol name: „alkyl“ alkohol)
• CH3-CH2-CH2-CO-O-(CH2)4-CH3 (apricot)
• full name: alkyl carboxylate
• CH3-CO-O-(CH2)4-CH3 (banana)
(methyl acetate = methyl ethanoate)
• CH3-CH2-CH2-CO-O-CH2-CH3 (pineapple)
• H-CO-O-CH2-CH3 (rum smell)
Properties and reactions of esters
• lower boiling points than carboxylic acids and
alcohols (~ absence of hydrogen bonds)
• less soluble in water than carboxylic acids
• esters have a fruity smell
2.3. ANHYDRIDES
R1―CO―O―CO―R2
• acid → anhydride
(acetic acid → acetic anhydride)
• organic, organic-inorganic
• reactions:
ester hydrolysis
examples
saponification = hydrolysis by a strong base
→ salt and alcohol
→ salts of long chain fatty acids are SOAPS
• acetic formic anhydride
polymerization → polyesters (from difunctional monomers)
• „phosphoglycerate“ (= phosphoric glyceric anhydride)
2.4. AMIDES
R―CO―NH2
• suffix: -amide (ethanamide)
• -ic or –oic acid → -amide (acetamide)
• substituted –NH2 group: N-alkyl…amide
• glutaric anhydride
2.5. ACYLHALIDES R―CO―X X = halogen
• acyl name + halide
• e.g.
acetyl chloride (= ethanoyl chloride)
butyryl bromide (= butanoyl bromide)
• substituted amide groups are found in proteins
(the peptide bond = „amide bond“)
• nitrogen atom contains an unshared pair of
electrons → delocalization ⇒ amides are not basic
• strong intermolecular H-bonds: amides are solids
• low MW amides are soluble in water
• carboxylic acid + ammonia (or amine) → amide + water
2.6. NITRILES
R―C≡
≡N
• hydrocarbon + suffix: -nitrile
or alkyl cyanide
CH3CN
• e.g
ethanenitrile or methyl cyanide
butanenitrile or propyl cyanide
• mostly toxic liquids
CH3CH2CH2CN
Exercise
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Exercise
H2N-CH2-CH2-CH2-COOH
CH3-CO-CH2-COOH
CH3-CH(OH)-CH2-COOH
CH3-CH2-CH2-CO-O-CH3
CH3-CO-COOH
CH3-CH2-O-CH3
CH3-CO-CH2-CH3
CH3-(CH2)14-COOH
CH3-CH2-CH2-COONa
(CH3-CH2-COO)2Ca
CH3-CH2-O-CO-H
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Carbonyl functional group:
H2N-CH2-CH2-CH2-COOH
CH3-CO-CH2-COOH
CH3-CH(OH)-CH2-COOH
CH3-CH2-CH2-CO-O-CH3
CH3-CO-COOH
CH3-CH2-O-CH3
CH3-CO-CH2-CH3
CH3-(CH2)14-COOH
CH3-CH2-CH2-COONa
(CH3-CH2-COO)2Ca
CH3-CH2-O-CO-H
>C=O
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γ-aminobutyric acid
acetoacetic acid
β-hydroxybutyric acid
methyl butyrate
pyruvic acid
ethyl methyl ether
ethyl methyl ketone
palmitic acid
sodium butyrate
calcium propionate
ethyl formate
Carbonyl compounds
• carbonyl- = oxo- group
• names: systematic or common (trivial)
• polar, planar, 2 nonbonded pairs of electrons (:O:)
• aldehydes: substitution principle or name
derived from common name of a corresponding
acid
• it is found in aldehydes and ketones
• ALDEHYDES: terminal carbon; -CHO
• in addition to a cyclic chain:
• prefix: formyl-
-al
-carbaldehyde
(1,2,3-propane tricarbaldehyde)
• KETONES: middle carbon; -CO• prefix: oxo- or keto-
- one
• ketones: substitution principle / radical function
principle or common names
• properties:
formation of H-bonds with water → solubility of low
MW carbonyl compounds in water (C1-C4)
sharp and irritant odour (↓ MW) – toxic comp., alergy;
or pleasant smell (↑ MW)
Carbonyl compounds
• important aldehydes:
Carbonyl compounds - REACTIONS
1. oxidation
methanal = formaldehyde
•
prim. alcohol → aldehyde → carboxylic acid
ethanal = acetaldehyde
•
sec. alcohol → ketone → no more oxidized
2,3-dihydroxypropanal = glyceraldehyde
Tollens´ reagent: [Ag(NH3)2]+ → Ag
benzaldehyde (bitter almond odour, little toxic)
Benedict´s or Fehling´s solution: Cu2+(l) → Cu2O (s)
• important ketones:
2. reduction
propanone = dimethyl ketone = acetone
•
aldehyde → primary alcohol
1,3-dihydroxypropanone = dihydroxyacetone
•
ketone → secondary alcohol
ketones are more narcotic than aldehydes
Alcohols
• contain the hydroxyl –OH functional group
Alcohols - properties
• primary / secondary / tertiary
• low MW alcohols: colourless liquids, specific
odour (unpleasant from C4), narcotic effect, toxic
• monofunctional / polyfunctional
• polyfunctional alcohols: sweet taste
• naming: -ol (or alkyl alcohol)
-diol (or alkyl glycol)
–triol,...
• higher alcohols (from C12): solid compounds
• -OH attached directly to the benzene ring
→ phenols (= group name)
If the hydroxyl group is not the principle one:
hydroxy-
• H-bonds → solubility in water, higher boiling
points than alkanes
• structure:
polar functional group
nonpolar hydrocarbon chain
hydrophobic properties increase with MW
Alcohols – important examples
• methanol = methyl alcohol
• ethanol = ethyl alcohol
Alcohols - toxicity
Ethylene glycol
• toxic: 50 mL, lethal: 100 mL
• ethane-1,2-diol = ethylene glycol
Methanol
• propane-1,2,3-triol = glycerol
• 5-10 mL toxic, 30 mL lethal
• cyclohexanol, inositols
• cholesterol
! add structure formulas !
• loss of eyesight, metabolic acidosis
Ethanol
• lethal: 6-8 g/kg (∼ 1 L of vodka)
• degradation: oxidation of 0,15 g/kg/hour
0,5 L of beer (4%) ∼ 20 mL of ethanol = 16 g
70 kg man: 0,7 x 70 = 49 kg (L) water
i.e. 16 g etOH / 49 L = 0,33 g / L = 0,33 ‰
Color Atlas of Biochemistry / J. Koolman, K.H.Röhm. Thieme 1996. ISBN 0-86577-584-2
29,4 kJ/g of ethanol
Obrázek převzat z: Color Atlas of Biochemistry / J. Koolman, K.H.Röhm. Thieme 1996. ISBN 0-86577-584-2