Chapter 26, 27 - Organic Chemistry Y13 Flashcards
what is an alkene
Double carbon bond
CnH2n
-ene
What is an alcohol
OH
-ol
hydroxy-
What is an ether
O in the middle
-oxy-
What are Haloalkanes
-halogen
Chloro-
Brromo-
iodo-
What are aldehydes
Double oxygen bond on the end of chain
-al
What are Ketones
Double oxygen bond in the middle of chain
-one
oxo-
What are carboxylic acids
COOH
-oic acid
What are nitriles
CN
-nitrile
What are arenes (aromatics)
C6H6
-benzene
-phen
What are amines
NH2
-amine
amino-
What are esters
COO
-oate
What are amides
Double oxygen bond and NH2
-amide
What are acyl chlorides
Double oxygen bond and chloride
-oyl chloride
What are acid anhydride
Double oxygen bond - oxygen - double oxygen bond
-anyhydride
What makes carboxylic acids have high boiling points
Hydrogen bonding
What happens to solubility of carboxylic acids as Mr increases
It decreases
Why are small carboxylic acids soluble
They can hydrogen bond with water
How can carboxylic acids be made
Oxidation of aldehydes
Reflux of primary alcohols
What type of acids are carboxylic acids
Weak acids
What reactions can carboxylic acids do
Bases
Alkali’s
Metals
Carbonates
What rate of reactions are carboxylic acid reactions
slow
How are esters named
The first part of the name is the side with the second oxygen on it
The second part is the carbon in the COO and any to the other side of it
What are the uses of esters
Food flavouring’s
Solvents
Perfumes
Plasticiers
What is the name for making esters
esterification
How can esters be made
Reaction of carboxylic acids and alcohols
Reversible and slow reaction
Forms water
What reactions can esters do
Hydrolysis
What is hydroylsis
The reverse of esterification
Reaction of ester
What conditions can hydrolysis be done in
Acidic or alkaline
What is hydrolysis in acidic conditions like
Reaction of ester with water forms carboxylic acid and alcohol
Reaction is slow and reversible
What is hydrolysis in alkaline conditions like
Reaction of ester with strong base forms salt of carboxylic acid and an alcohol
Not reversible
Saponification
What are the other uses of esters
Making soap
making bio diesel
What are lipids
They are naturally occurring esters that are found in animal fat and vegetable oils
What do lipids consist of
3 long chain carboxylic acids, known as fatty acids, joined through glycerol which has 3 alcohol groups
What are the fatty acids like
Saturated or non-saturated
What are lipids derived from mainly unsaturated fatty acids like
Liquids at room temperature and are called oils
What are lipids derived from mainly saturated fatty acids like
Solids and called fats
How is soap made
Saponification
Made from heating fats/oils with sodium or potassium hydroxide
How do soaps work
2 ends
Long hydrocarbon chain (water repelling)
Short ionic end (water attracting part)
What is biodiesel
It is a fuel that can be used in most diesel engines in place of diesel made from crude oil
They are methyl esters of long chain carboxylic acids
How are bio diesels made
Reacting lipids in vegetable oils with methanol using a potassium hydroxide cataylst
How bioethanol is produced
Fermentation
Converting of glucose into alcohols and carbon dioxide
C6H12O6 → 2C2H5OH + 2CO2
How is glucose made
It is made through photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
Plants take in carbon dioxide and water and convert it into glucose and oxygen
How is bio ethanol used as a fuel
It undergoes combustion releasing energy
2C2H5OH + 6O2 → 6H2O + 4CO2
What are the problems with bio ethanol
Deforestation / Sacrifice land that could be
used for food
Loss of biodiversity / habitat
6CO2 in and 6CO2 out but It isn’t actually C neutral as fuel is used in production, distribution, etc
What is an acyl group
CO
Double bond with oxygen
What are acid derivitives
They are a group of compounds all which have the acyl group within their structure
What are the acid derivitives
Acyl chlorides
Acid Anhydrides
Amides
What reactions do acyl chlorides do
Water
Alcohols
Ammonia
Primary Amines
What is acylation
It is the process of introducing an acyl group into another molecule
How does acyl chlorides react with water
(hydrolysis)
Mechanism Name
They react to form a carboxylic acid and hydrogen chloride
Nucleophilic addition- elimination mechanism
What is the mechanism for acyl chlorides with water like
Lone pair on oxygen from water reacts with carbon with the double oxygen bond
One of the bonds breaks with oxygen towards oxygen atom
Lone pair on oxygen reacts with carbon to form a double bond
Bond with chlorine breaks
Bond between oxygen and hydrogen breaks from water towards oxygen
What does the reaction between acyl chlorides and alcohols form
Esters and hydrogen chloride
Nucleophilic addition - eliminations mechanism
What is the mechanism for acyl chlorides with alcohols like
Lone pair from OH reacts with carbon in acyl group
One of the bonds between carbon and oxygen breaks towards oxygen atom
Lone pair on oxygen reacts with carbon forming double bond
Bond between carbon ad chlorine breaks
Bond between hydrogen and oxygen breaks from alcohol towards oxygen atom
What are the benefits of making esters from acyl chlorides and alcohols
not reversible and faster
What does the reaction between acyl chlorides and ammonia form
Amide and ammonium chloride
Nucleophilic addition - elimination mechanism
What is the mechanism for acyl chlorides with ammonia like
Lone pair from ammonia reacts with carbon from acyl group
One of the Bonds between oxygen and carbon breaks towards oxygen
Lone pair on oxygen reacts with carbon forming a double bond
The bond between the carbon and chlorine breaks
Other NH3 reacts with Hydrogen from ammonia
What does the reaction between acyl chlorides and primary amines form
N- substituted amide
ammonia chloride + chain
What is the mechanism for acyl chlorides with primary amines like
Lone pair on amine reacts with carbon from acyl group
One of the bonds breaks between carbon and oxygen towards oxygen
Lone pair on oxygen reacts with carbon to form double bond
Bond between carbon and chlorine breaks
Bond between hydrogen and Nitrogen breaks towards nitrogen
What are the reactions of acid anhydrides like
Similar to those of acyl chlorides but less vigorous
What does the reaction of acid anhydrides with water form
2 carboxylic acids
What does the reaction of acid anhydrides with alcohols form
Ester and carboxylic acid
What does the reaction of acid anhydrides with ammonia form
Amide and ammonium ester
What does the reaction of acid anhydrides with primary amines form
Amide with hydrogen replaced and ammonium ester
What else does acid anhydrides react with
Hydroxides
What are the advantages of acid anhydrides
Less corrosive as acid isn’t formed
Less reactive with water
Safer
What are arenes
Homologous series based on benzene
What is the equation and symbol for benzene
C6H6
Hexagon with a circle inside
What are arenes also known as
Aromatic compounds
What are the features of benzene
Colourless liquid at room temperature
Immiscible with water
Very unsaturated
Very stable
How are arenes named
Benzene forms the root of the name for most compounds
If more than 1 substituent is on the ring, then their position must be shown
In some cases the benzene ring is seen as the substituent known as phenyl group
What groups make the benzene the substituent
Amines - NH2
Carbon chains
Double carbon bonds chains
Ketone
Alcohol
Esters
Amides
When was benzene discovered
1825 by Faraday
When was the formula of benzene discovered
1835
When was the first possible structure of benzene created
1865
By Kekule
What structure of benzene was first made
cyclohexa-1,3,5-triene
What is the structure of benzene
It is a planar molecule
Each carbon bonds with 2 carbons and a hydrogen atom
It leaves an electron in the p-orbital from each carbon
These overlap and become delocalised forming a ring of negative charge ‘electron cloud’ above and below the plane
What evidence is used to support the delocalised structure
Addition reactions
Bond length
Enthalpy of hydrogenation values
How do addition reactions prove the delocalised structure
If benzene contained double carbon bonds then it would undergo addition reactions which it doesn’t
How do bond lengths prove the delocalised structure
X-ray diffraction show the bonds in benzene are all the same and aren’t equal to the length of a single or double carbon bond
It is an intermediate between the 2
How does the enthalpy of hydrogenation values prove the delocalised structure
The value for benzene is less than the value for cyclohexatriene which would be expected to be the same if Kekules structure was right
Why is benzene more stable than cyclohexatriene
Because of the delocalisation of electrons and is known as delocalisation energy (stability)
What are the typical reactions of aromatic compounds
Electrophilic substitution reactions
What does benzene attract
The ring of delocalised electrons attracts electrophiles
What reactions do aromatic compounds do
Nitration
Friedal Crafts Acylation
What does nitration involve
Replacing 1 of H’s on the aromatic ring with NO2 group
Warmed to 50 degrees with a mixture of concentrated nitric and sulphuric acid
What is the equation for nitration which generates the electrophile
HNO3 +H2SO4 > NO2+ + HSO4- + H2O
NO2+ is nitronium ion (electrophile)
What is the mechanism for nitration
Inside of benzene attacks N on NO2+
Forms bond with carbon with other hydrogen atom and half circle in benzene
Hydrogen bond breaks towards the centre of benzene
Product formed with H+ ion
What is the equation for nitration which generates the catalyst
HSO4- + H+ > H2SO4
What are the uses of nitration
Production of explosives
Producing aromatic amines
What is the name of TNT
2,4,6-trinitromethylbenzene
What are aromatic amines used as
Industrial dyes
What is the reaction to produce aromatic amines
Nitrobenzene is reduced using concentrated HCl and a Tin cataylst
What do Friedel Crafts Acylation involve
Replacing one of the H’s on the aromatic ring with acyl group
Aromatic compounds reacted with acyl chlorides or acid anhydrides with AlCl3 catalyst
What is the equation for acylation with acyl chloride which generates the electrophile
AlCl3 + RCOCl > AlCl4- + RCO+
What is the equation for acylation with acid anhydride which generates the electrophile
RCOOCOR + AlCl3 > RCO+ + AlCl3OCOR-
What is the mechanism for acylation of aromatic compounds
Inside of benzene attacks carbon of electrophile
Bonds with benzene forms with hydrogen bond as well and half benzene circle
Hydrogen bond breaks towards inside of benzene ring
Product formed with H+ ion formed
What is the equation from acylation which forms the catalyst back
AlCl4- + H+ > AlCl3 + HCl
Why is hot water used in recrystallisation
Obtain saturated solution
Why is the minimum amount of water used for recrystallisation
allow crystallisation on cooling
Why is the product filtered hot in recrystallisation
remove insoluble impurities
Why is the product cooled with ice in recrystallisation
increase the yield of crystals formed
Why are the crystals compressed in the funnel
Allows better drying
Why is the product washed with cold water
remove soluble impurities
What is the difference between a cyclohexene with the double bonds next to each other and not next to each other
Cyclohexene with double bonds next to each other, the outer electrons become partially delocalised so is more stable
Which bond is longer:
Single carbon bond or double carbon bond
Single carbon bond is longer
Why does the reduction of aminobenzene from nitrobenzene form an aqueous solution
Aminobenzene is present as an ionic salt in the solution
What is the equation for a nitrobenzene to an aminobenzene
C6H6(NO2) + 6[H] -> C6H6(NH2) + 2H2O
Sn/HCl or Fe/HCl then NaOH
What is the equation for the reduction of chromate ions
CrO72- + 14H+ + 6e- -> 2Cr3+ + 7H2O
What is the equation for the reduction of Tollens reagent
[Ag(NH3)2]+ + e- -> Ag + 2NH3
What does Tollens reagent oxidise aldehydes to
Carboxylic acids
Why is the reaction between a benzene compound and ammonia unlikely
Because ammonia is a nucleophile
Benzene repels nucleophiles
How does carbon dioxide cause global warming
C=O bonds in carbon dioxide absorb infrared radiation
This causes IR radiation to not escape from the atmosphere emitted by the Earth
This energy is transferred to other molecules in the atmosphere by collisions
Why does carbon dioxide absorbs infrared radiation
C=O bonds vibrate at the same frequency as IR
