chemistry - physical properties of organic chemistry

Physical Properties of Organic Compounds PROPERTIES TYPES

Alkanes Aliphatic Aromatic

Alkenes Aliphatic Aromatic

Arenes Benzene

Halogen Derivatives Haloalkanes Haloarenes

Arenes

CH3 EXAMPLE

NOMENCLATURE

H3C

CH3

CnH2n+2 ~e

H2C

CnH2n Cyclo~e

CH2

CH3Cl

CnH2n

CnH2n–2

Presence of cis and trans isomer

↑es with ↑ C g

↑es with ↑g C ↑ in Mr = More e = more id-id *Branching ↓ bp Branched isomer has lower surface area than straight-chain isomer = lower id-id interactions. –

BOILING POINT

Higher bp than corr. aliphatic alkanes

MELTING POINT

SOLUBILITY (POLAR SOLVENTS)

SOLUBILITY (NON POLAR SOLVENTS)

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C6H6 Phenyl~

Variable

Higher bp than corr. aliphatic alkenes

Higher bp than 6C alkane (69°C) and 6C alkene (63.5°C). Comparable bp with cyclohexane (81°) and cyclohexene (83°C).

5.5°C Higher mp than corr. aliphatic alkanes

↑es with ↑g C Trans–isomers pack better into a regular lattice i.e. higher bp than cis-isomers.

CnH2n+1X

80°C

Similar bp as alkane with same number of C *bp may be slightly higher for cis isomers as the dipole moment do not cancel out = pdpd interactions  Higher bp

↑es with ↑g C M.P affected by how close the molecules can pack together Branchg may ↑ mp Though less efficient id-id forces, isomer able to pack into regular arrays

Cl

Higher mp than corr. aliphatic alkenes

Insoluble

Insoluble

Soluble (CCl4)

Soluble

Higher mp than 6C alkane (– 95°C) and 6C alkene (–138°C). Comparable mp with cyclohexane (6.5°). Has higher mp than cyclohexene (–104°C)

Dependent on e– cloud size (molecular weight)

Dependent on molecular weight and shape. For isomers, 1,4usually has the highest mp compared to 1,2and 1,3-. More symmetrical molecular fits better into crystal lattice.

Insoluble Soluble (acts as solvent)

C6H5X

Higher bp than corr. alkanes due to larger Mr. (for some also due to presence of pd-pd)

Bp ↑es -with size of X. Effect of id-id forces outweigh ↓ polarity of bond i.e weaker pd-pd -with more subsn of X

Higher mp than corr. alkanes due to larger Mr.

Comparable bp to corr. alkyl halides i.e higher bp than corr. alkanes

Comparable mp to corr. akyl halides i.e higher bp than corr. alkanes

Insoluble (unable to form H bondg with water)

Soluble

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Physical Properties of Organic Compounds DENSITY (WRT WATER)

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Less Dense

Less Dense (Denser than aliphatic alkanes)

Less Dense

Less Dense (Denser than aliphatic alkenes)

Less Dense

Less Dense

Denser

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Physical Properties of Organic Compounds PROPERTIES TYPES

Hydroxy Compounds Alcohols Phenols

Carbonyl Compounds Aldehydes Ketones

OH EXAMPLE

NOMENCLATURE

BOILING POINT

MELTING POINT

SOLUBILITY (POLAR SOLVENTS)

CnH2n+1OH CnH2n+2O Much higher than correspong alkanes.IMF H bondg. Lower alc are liquids at room temp till 12C Factors *Length of Alkyl Chain (id-id) *Branching

C6H5OH

182°C Higher than hexanol (156.5°C)

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O

O C

O

R

R

~al/formyl~

~one/oxo~

Polar compds. Higher bp than non-polar compds of similar Mr. Lower bp than acid and alc. because no H bonding

Much higher than correspong alkanes.

41°C Higher than hexanol (–52°C)

Lower alc are soluble. Solubility ↓ as C ↑ due to ↑ h.phobic nature

Partially soluble in rt due to H bg but has big h.phobic ring. Solubility is enhanced by heating or addition of alkali.

Polar compds. Higher mp than nonpolar compds of similar Mr. Lower mp than acid and alc. because no H bonding

RCOOH

H3C

Lower aldehydes and ketones are soluble in water, ability to form H bonding with water

C

Cl

ethanoyl chloride

~oic acid

~yl chloride

Higher bp due to H bonding in polar compd. Stronger than alcohol because -OH is more polarized (presence of e– carbonyl groups)

Higher mp due to H bonding in polar compd.

Branching & packing affects mp too.

SOLUBILITY DENSITY

R C

CH3OH

Lower acids are soluble in water

Nitrogen Compounds Amines Amides O R N R R C N R R R ~amine/ 1°: ~oic acid ~amide 2°: alkyl on N as sub. amino~

Acid chlorides: Lower bp wrt to carboxylic acid because of its inability to form H bonding.

Acid amides: Has –NH2 group and posses IM H bonding. Higher bp.

Acid chlorides: Polar, no H Bg Acid amides: Polar, H Bg Acid derivat.s: depend on size Amides & Acid Chloride: soluble

Polar compds (ex 3°) can H Bondg. Higher mp than nonpolar compds of similar Mr but lower than alc and carboxylic acid.

High bp due to H bondg, usually higher than corr carboxylic acids. (1° or 2°)

Higher mp than non-polar compds of similar Mr but lower than alc and carboxylic acid.

High mp due to H bondg, usually higher than corr carboxylic acids.

Lower amines are soluble due to H Bondg

Lower amides are soluble due to H Bondg

Soluble (solubility decreases with increasing C for all these compounds)

(NON POLAR SOLVENTS) (WRT WATER)

H

Carboxylic Acid & Derivatives Carboxylic A. A. Derivatives

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