S3.2 Functional groups: Classification of organic compounds

What are the 5 types of formulas organic compounds can be represented in?

Empirical

Molecular

Structural (full and condensed)

Stereochemical

Skeletal

What is a homologous series

A group of compounds with the same functional group and general formula, where successive members differ by a CH2 group

What is a functional group?

An atom or group of atoms that gives organic compounds their physical and chemical properties

Why does boiling point increase as number of carbon atoms in a homologous series increases?

Molecule size increases→larger electron cloud→stronger London dispersion forces

Why does solubility of alcohols decrease as the carbon chain gets longer?

Alcohols form hydrogen bonds with water due to the presence of OH.

As non-polar chain increases, it overpowers polar OH grp, disrupting its hydrogen bonding=less solubility

What are advantages and disadvantages of using alcohols as fuels?

Adv: alcohols are renewable or burn cleanly (less soot)

Disadv: they have lower energy density than hydrocarbons or their production compete with food crops for land

Name a structural isomer with formula C2H2Br that does not show cis-trans isomerism

1,1-dibromoethene

Which ⁣homologous ‍family is ‌characterized by ‌a ‍functional group ‍in which ‍carbon ‌and nitrogen ‍are joined ‍by ‍a triple ‍bond?

Nitriles

Name the reaction undergone and which substances are needed to convert an alkene to alcohol (eg: oct-4-ene to octan-4-ol)

Hydration reaction

Steam and concentrated phosphoric acid or sulfuric acid catalyst

What’s the different between an alkene and alkyne in terms of structure?

An alkyne has a C triple bond while alkene has C double bond

Which reactions do alkanes undergo?

Combustion

Free radical substitution

Which reactions do alkenes and alkynes undergo?

Combustion

Electrophilic addition

Which reactions do aldehyde undergo?

Oxidation (to form carboxylic acid)

Reduction (to form primary alcohols)

What is the functional group of aldehyde?

R-CHO (double C-O bind)

Which reactions do ketones undergo?

Reduction

What is the functional group of a ketone?

R-CO-R’ (double bond on C-O)

Which type of reactions do esters go through

They are formed between nucleophilic reactions between alcohols and carboxylic acids

What is the functional group of an ether?

R-O-R’

Which reactions do alcohols undergo?

Combustion

Oxidation

Nucleophilic substitution with carboxylic acid to form esters

Which types of reactions do carboxylic acids undergo?

Nucleophilic substitution with alcohols to form esters

Reduction

What is a homologous series?

A series of organic compounds of the same family which differ by a common structural unit (-CH2)

True or false: members of a homologous series have different chemical properties and the same physical properties

False. They have similar chemical properties and distinct physical properties

What is an isomer?

Molecules that share same molecular formula but different structural formula

Between branched chain isomers and straight chain, which has higher bp and why?

Straight chain

Branches prevent molecules from getting close tg, hence, weaker London forces→lower bp

Rank butanoic acid, butanal, butanol and butane from least to most likely to form hydrogen bonds and explain why

Butane<butanal<butanol<butanoic acid

Butanoic acid forms stronger H-bonds as its carboxyl grp has 2 oxygen atoms, allowing formation of 2 H-bonds rather than 1

The OH grp in alcohols allows both hydrogen bonds which donation and acceptance (compared to butanal O)

Why are alcohols general more soluble in water than aldehydes of similar molecular mass?

The OH grp in alcohols allows for both hydrogen bonds donation and acceptance