CHEM - ORG

Optical Isomers (definition)

molecules with the same molecular formula but different (3D) arrangements of the same atoms in space

What is required for geometric isomers

Carbon-carbon double bond and 2 different atoms/group of atoms attached on each carbon of the double bond

Optical Isomers

contain a chiral carbon and are therefore non-superimposable enantiomers

What is a chiral carbon

C atom that has 4 different atoms/group of atoms attached

Optical isomers difference

rotate plane polarised light in opposite directions. One optical isomer will rotate plane-polarised light in one direction while the other will rotate it in the opposite direction

What are enantiomers

molecules that are optical isomers

Racemic mixture

mixture that contains equimolar quantities of each enantiomer 50/50, therefore the rotation of plane polarised light cancels out, so racemates are not optically active

Naming alcohols in presence of other functional groups

hydroxy

Which type of alcohol is more reactive

Tertiary

What is distillation and what does it produce

• oxidising alcohol by heating it with MnO4-/H+

• produce aldehyde

How does distillation work

seperates organic molecules by evaporating and condensing molecules based on boiling points

How is an aldehyde formed and extracted in distillation

has a lower bp than alcohol, so it vaporises when heated and is then condensed and collected before it is further oxidised to a carboxylic acid

Why is reflux used

ensures that volatile molecules are containde when the reaction is heated so that an alcohol is fully oxidised to carboxylic acid

How does reflux work

as the alcohol is heated with MnO4-/H+, it produces aldehyde, which vaporises. As it travels upwards, the vapour is condensed in the condenser, and drops back into the reaciton micture to be further oxidised to carboxylic acid

What is soluble in Luca’s reagent

Alcohols

Reactions with lucac’s reagent

Tertariy: immediately,cloudy Secondary: cloudy after a few minutes, Primary: no visible reaction

Hydration & Reactant

Alkene > Alcohol

H2O

H2SO4 (dilute) (catalyst)

When to use Markovnikov’s Rule

hydration (alkene > alcohol)

If assymetric

Haloalkanes > Alcohol (reactant)

OH-(aq)

Dehydration (reaction + reactant)

Alcohol > alkene

H2SO4 (conc)

When to use Anti-Markovnikov/Saytzeff’s

dehydration (alcohol > alkene)

Alcohol to Haloalkane (reactant)

SOCl2

What are aldehydes

CHO - one H attached to carbonyl

What is ketone

2 carbons attached to carbonyl group

How to make ketone

oxidising secondary alcohol under reflux usong Cr2O72-/H+

Aldehyde > Primary Alcohol

NaBH4 (reduction)

Ketone > Secondary Alcohol

NaBH4 (reduction)

What does tollen’s reagent only react with

Aldehyde, forms silver mirror and carboxylic acid

What does Benedicts/Fehling’s solution react with

aldehyde, blue solution changes to brick red precipitate, forms carboxylic acid

What does ketone react with

Nothing (not even potassium dichromate or permanganate)

What are acyl chlorides

carboxylic acids with the -OH group replaced with a chlorine atom

Generalisation about all acyl chloride reactions

all reactions are exothermic (heat releasing) and give high yield products. HCl gas (white fumes) are observed

Acyl chloride > Carboxylic acid

Water reacts with acyl chloride to produce HCI gas and a carboxylic acid

Acyl Chloride > Amide

Ammonia(alc)

Acyl Chloride > Ester

alcohols react with acyl chlorides to form HCI gas and esters

What catalyst is needed to form esters from acyl chlorides and alcohol

none

What is an amide

Carboxylic acid derivative in which the -OH group is replaced by NH2 (primary), NH (secondary), N(teritary)

Chemical properties of amides

• weaker bases than amines

• do not react with litmus

• do not react with acids

What is a dipeptide

Formed when H from NH2 and OH from COOH form water and the

molecules join together

What is hydrolysis

a reaction using water and heat (under reflux) to split large organic compounds (esters, amides) into smaller ones. It breaks C-N bonds, adding -H and -OH from water

What types of hydrolysis are there

acid catalysed and base catalysed

What are condensation polymers

a small molecule (H2O or HCI) is expelled when 2 monomers join

How are Polyesters formed

reacting “double-ended” molecules (e.g. diols, dicarboxylic acid, acyl chloride)

Alkane > Haloalkane

BR2/Cl2 Halogenation (slow requires UV light)

Alkene > Haloalkane

HCl (hydrohalogenation), fast

Alkene > Alcohol

H2O/H+, heat, hydration, H2SO4 (dilute)

Alkene > Dibromoalkane

Br2, halogenation

Haloalkane > Amine

NH3(conc) warm

Haloalkane > Alcohol

KOH (aq), reflux, substitution, heat

Alcohol > Alkene

H2SO4 (conc)

Alcohol > Haloalkane (chloroalkane)

SOCl2, reflux

Alcohol > Ketone

Cr2O72-/H+, heat

Alcohol > Carboxylic Acid

Cr2O72-/H+ reflux

Alcohol > Aldehyde

Cr2O72-/H+

Alcohol + Carboxylic acid > Ester

H2SO4 (conc)

Aldehyde > Carboxylic Acid

Cr2O72-/H+ under reflux

Carboxylic Acid > Acid Chloride

SOCl2 (reflux)

naming esters

1st part comes from number of C atoms in the alcohol group and the 2nd part comes from number of C atoms in the carboxylic acid group (ethyl propanoate)

Alkene > Alkane (reactants, a catalyst if need be, classify)

H2, Pt/Ni catalyst, additon

what do all addition reactions involve

alkene

Markovnikov’s Rule

hydrogen atom is attached to the carbon atom with the highest number of hydrogen atoms already attached (major product)

What do all elimination reactions produce

alkene

Haloalkane > Alkene

KOH(alc), elimination

Saytzeff’s/Anti-Markovnikov’s Rule

Major product is the one where the hydrogen atom is removed from the carbon with the least number of hydrogens already attached

What does an addition reaction require and what happens

addition of water across an alkene’s double bond, requires an acid catalyst

In which reactions do you use Markovnikov’s Rule

addition reactions

What happens in elimination reactions

atoms are removed from two neighbouring carbon atoms in the main chain

Alcohol > Alkene

H2SO4 (conc), elimination reaction

In which reactions to use Saytseff’s Rule

elimination reactions

Haloalkane > Alkene

KOH(alc), elimination

What happens in the Haloalkane > alkene reaction

hydrogen and halogen atom that were removed, combine to form HCl or HBr

Which alcohols can be oxidised

hydroxy group on the 1st carbon atom

Order of oxidising a primary alcohol

Alcohol, aldehyde, carboxylic acid

Order of oxidising secondary alcohol

Alcohol > Ketone

Ketone > Secondary alcohol

NaBH4

Aldehyde > Primary alcohol

NaBH4

Carboxylic acid > Primary alcohol

cannot happen because NaBH4 is not a strong enough reducing agent for this reaction to occur

Alkene > Diol

Only MnO4-/H+ (NOT DICHROMATE)

Cr2O72-/H+ for alkene > diol

cant use cuz its too strong, permangante is more mild

What happens during Carboxylic acid > Acyl Chloride

-Cl from SOCl2, bonds to the COOH (therefore removing -OH), SO2 is by product, the other -Cl from SOCl2, forms with -H from -OH to for HCl

Acyl Chloride > Carboxylic Acid

H2O

How do Acyl Chlorides react with water

vigorously

Acyl Chloride > Amide

NH3(alc), -NH2 from ammonia jumps on to form amide. Remaining hydrogen from ammonia combines with chlorine to form HCl

What happens every time carboxylic acid reacts

loses a hydrogen ion to form an ion or salt

Reaction for amine with water

CH3CH3NH2 + H2O > CH3CH2NH3+ + OH-

Reaction for amine with acid

CH3CH2NH2 + HCl > CH3CH2NH3+ + Cl-

What is a condensation reaction

reaction involving 2 smaller molecules together to create one large molecule

What happens during alcohol and carboxylic acid

water gets removed

What type of reaction is forming an ester

condensation reaction

Acyl Chloride + Alcohol > Ester

remove -Cl from acyl chloride and the hydrogen from the hydroxyl group of the alcohol

What is required for Alcohol + Carboxylic acid > Ester

H+/Heat, dehydrating agent

Acyl Chloride + Amine > Amide

remove -Cl from acyl chloride and a single hydrogen from the amine group in the amine

Hydrolysis

reaction where the large molecules are broken down into smaller molecules

Haloalkanes, polar or non-polar

Non-polar

Small amines, alcohols, and compounds with carbonyl group

Polar

Non-polar molecules and mp/bp

weak froces, does not take up much energy to be seperated