More polar, so boiling point higher than corresponding alkane or ether. Absence of H-bond, so boiling point lower than corresponding alcohol.
A- 1 0 Alcohol gives aldehydes: CH 3 CH 2 OH C u/ 350 o C CH 3 CHO + H 2 B- Secondary Alcohol gives Ketones: OH O CH3CHCH3 Cu/350 o C CH3CCH3 + H2 A- 1 0 Alcohol gives aldehydes: CH 3 CH 2 OH C u/ 350 o C CH 3 CHO + H 2 B- Secondary Alcohol gives Ketones: OH O CH3CHCH3 Cu/350 o C CH3CCH3 + H2
3] Ozonolysis of alkenes:
A) If dihalogen are terminal: CH3CHCl2 H2O/NaOH CH3CH(OH)2 H2O CH3CHO acetaldehyde B) If dihalogen aren’t terminal: CH3CCl2CH3 H2O/NaOH CH3COCH3 acetone
In presence of dry HCl aldehydes and ketones react with two equivalent of alcohols to form acetals and ketals
19 Acetal Formation Acetals are geminal diethers- structurally related to hydrates, which are geminal diols. hydrate (gem-diol) aldehydehemi-acetal acetal (gem-diether) ketonehemi-ketal ketal (gem-diether)
4-Reduction of Aldehydes/Ketones Hydrogenation Hydrogenation
Aldol Condensation - Under the influence of dilute base or dilute acid two molecules of an aldehyde or a ketone may combine to form b- hydroxaldehyde or b-hydroxyketone. This reaction is called aldol condensation.
The Aldol Condensation base an aldol ( -hydroxyaldehyde) ald + ol H3O+H3O+ - H 2 O , -unsaturated aldehyde aldols easily lose water to form a double bond
Aldol Condensation -- Mechanism fast slow enolate ion forms new C-C bond
Add ammonia solution to AgNO 3 solution until precipitate dissolves. Aldehyde reaction forms a silver mirror.
Tollen’s test Fehling’s test Schiff’s test Schiff's Test for aldehydes. Use 2 mL Schiff's reagent + 3 drops unknown. Positive test showing a magenta color after ten minutes.
29 A carboxylic acid Contains a carboxyl group, which is a carbonyl group (C=O) attached to a hydroxyl group (— OH). Has the carboxyl group on carbon 1. carbonyl group O CH 3 — C—OHhydroxyl group or CH 3 COOH carboxyl group
30 The IUPAC names of carboxylic acids Replace the -e in the alkane name with -oic acid. CH 4 methane HCOOH methanoic acid CH 3 —CH 3 ethane CH 3 —COOH ethanoic acid Number substituents from the carboxyl carbon 1. CH 3 O | ║ CH 3 —CH—CH 2 —C—OH methylbutanoic acid
33 Methanoic acid (formic acid) O ║ H ─ C ─ OH ethanoic acid (acetic acid) O ║ CH 3 ─ C ─ OH
Physical properties: 1] They form hydrogen 2] comp. 1-7 soli in H 2 O. 3] mor than 7 carbon less soli. (bec. R increased) 4] Aromatic acids insoluble. In H 2 O 5] BP. Acid > Alcohol
35 Carboxylic acids Are strongly polar. Have two polar groups: hydroxyl ( − OH) and carbonyl (C=O). δ - O ║ δ + δ - δ + CH 3 C O H
36 The boiling points of carboxylic acids Are higher than alcohols, ketones, and aldehydes of similar mass. Are high because they form dimers in which hydrogen bonds form between the polar groups in the two carboxyl groups. O H—O || | CH 3 —C C—CH 3 | || O—H O A dimer of acetic acid
37 Carboxylic acids Form hydrogen bonds with many water molecules. With 1-4 carbon atoms are very soluble in water. Water molecules
Preparation of carboxylic acid 1] Oxidation a) 1 alcohols & Aldehydes
39 Carboxylic acids can be prepared by oxidizing primary alcohols or aldehydes. The oxidation of ethanol produces ethanoic acid (acetic acid). OH O O | [O] || [O] || CH 3 —CH 2 CH 3 —C—H CH 3 —C—OH ethanol ethanal ethanoic acid (ethyl alcohol) (acetaldehyde) (acetic acid)
2] Carbonation of Grignard reagent:
Reactions of acids 1)Salt formation: it react with strong base & we can use Ca or K It reacts with weak base Sodium bicarb. Can be used to distinguish between carboxylic acid and phenols
nucleophilic substitution carboxylic acid + alcohol H+H+ + H 2 O ester condensation reaction reverse =hydrolysis ester+ H 2 O H+H+ carboxylic acid + alcohol 2) Formation of Ester:
4) Formation of acid anhydride: 2) Formation of Ester: 3) Formation of acid chloride: 2RCOOH + P2O5 (RCO)2O + H2O 2CH3COOH + P2O5 (CH3CO)2O + H2O
5- Reduction: RCO 2 H + LiAlH 4 ; then H + RCH 2 OH 1 o alcohol 5- Reduction: RCO 2 H + LiAlH 4 ; then H + RCH 2 OH 1 o alcohol 6- Decarboxylation:( Soda lime) CH3COOH + NaOH/CaO CH4 + Na2CO3 Alkane
aldehydeRCOOHketone ROR alkyne alkene RH RX ROH Alcohols are central to organic syntheses