General Organic Chemistry

The larger the force of attraction between the molecules more would be its boiling point. Or the larger the electronegativity difference between the molecule, the more would be its polarity or boiling point. The force of attraction generally increases in the following order: electrostatic force of attraction hydrogen bonding > dipole-dipole attraction > van der Waals force of attraction.By the logic of which,Alkanes < Alkenes < Alkynes < Haloalkanes < Ether < Ester < Amine < Aldehyde < Ketone < Alcohol < Carboxylic Acid < Amide.I- AlkaneII- AlcoholIII- AldehydeIV- Carboxylic Acid$ $

To determine which molecules are aromatic using Huckel's rule, we check if they follow the -electron rule, where is a non-negative integer ( ).Molecule : It has -electrons (from three double bonds). Huckel's rule: , which gives . It is aromatic.Molecule : It has -electrons. Huckel's rule: , which gives . It is aromatic.Molecule O: It has -electrons ( 4 from double bonds and 2 from a lone pair on nitrogen). Huckel's rule: , which gives . It is aromatic.Molecule P: It has -electrons (from two double bonds). Huckel's rule: , which gives . It is not aromaticTherefore, the aromatic molecules are , and O .

Hückel's Rule of Aromaticity:Compound I:All carbon atoms are hybridized.Contains three carbon atoms forming a conjugated system with a positive charge, resulting in π electrons.Applying Hückel's rule: electrons, where .Hence, Compound I is aromatic.Compound II:This is the furan cation, which is cyclic and planar.Contains 6 π electrons: 4 from the double bonds and 2 from the lone pair on the oxygen atom.According to Hückel's rule, for , .Therefore, Compound II is aromatic.

To determine the most acidic compound among phenol, benzoic acid, picric acid, and o-nitrophenol, we must consider the electron-withdrawing effects of the substituents and their ability to stabilize the conjugate base.1.Phenol: Phenol has a hydroxyl group attached to a benzene ring. It is relatively acidic due to the resonance stabilization of the phenoxide ion, but it lacks strong electron-withdrawing groups to further stabilize the conjugate base.2.Benzoic Acid: Benzoic acid has a carboxyl group ( -COOH ) attached to a benzene ring. The carboxyl group is a strong electron-withdrawing group, significantly stabilizing the conjugate base (benzoate ion) through resonance and inductive effects, making benzoic acid more acidic than phenol.3.Picric Acid (2,4,6-trinitrophenol): Picric acid has three nitro groups at the 2,4 , and 6 positions. Nitro groups are very strong electron-withdrawing groups that greatly stabilize the conjugate base through resonance and inductive effects. The extensive stabilization provided by the three nitro groups makes picric acid extremely acidic.4.o-Nitrophenol: o-Nitrophenol has a nitro group at the para position relative to the hydroxyl group. The nitro group is a strong electron-withdrawing group and significantly stabilizes the phenoxide ion through resonance and inductive effects, making o-nitrophenol more acidic than phenol but less acidic than compounds with additional or stronger electron-withdrawing groups.Picric acid is the most acidic compound among the given options. The three nitro groups provide strong electron-withdrawing effects, which greatly stabilize the conjugate base, making picric acid significantly more acidic than the others.

Solution:Step 1: Write the carbon skeleton correctlyName:2-methyl-3-phenyl-pentan-1-alParent chain:pentan-1-al(5 carbons, aldehyde at C-1)Substituents:Methyl (–CH₃)atC-2Phenyl (–C₆H₅)atC-3Structure (numbered):O||C1–C2–C3–C4–C5| |CH3 PhO||C1–C2–C3–C4–C5| |CH3 PhCHO–CH(CH3)–CH(Ph)–CH2–CH3Step 2: Identify α- and β-carbonsα-carbon: Carbonadjacent to –CHOHere →C-2β-carbon: Carbonnext to α-carbonHere →C-3👉 β-hydrogens are hydrogens attached toC-3 onlyStep 3: Count hydrogens on β-carbon (C-3)C-3 is bonded to:C-2C-4Phenyl group (–Ph)That makes3 σ-bonds, so carbon issp³and has:4 − 3 = 1 hydrogenSo far:β-hydrogens on C-3 = 1Step 4: Important concept — consider β-hydrogens on substituent alkyl groupsThemethyl group at C-2is alsoβ to the –CHO group(because its carbon is two bonds away from –CHO via C-2).Methyl group (–CH₃):Has3 hydrogensAll areβ-hydrogensStep 5: Add all β-hydrogensSourceβ-HydrogensC-31Methyl at C-23Total4✅Answer: 4