Organic Flashcards
What is the simplest hydrocarbon
Benzene , C6H6
What are aromatic hydrocarbons
Family of cyclic hydrocarbons
What functional group do alcohols contain
Hydroxyl group (OH)
What makes a primary alcohol
When the hydroxyl group is on the end, hence the carbon the OH is attached to is only attached to one other carbon for example 1-propanol CH3-CH2-CH2-OH
What do organic compounds with a hydroxyl functional group end in
-ol eg Pentanol
What constitutes a secondary alcohol
When the C the OH is bonded to is bonded to 2 other carbons,
Eg 2-Propanol
What constitutes a tertiary alcohol
When the C the OH is bonded to is attached to 3 other carbons
Eg, methyl 2-propanol
What is the condensed formula of aldehydes, plus two examples
R-CHO, methanal or ethanal
What is the condensed formula of ketones and what are two examples
R-CO-R’
Propanone and 2-pentanone
What is the condensed formula of carboxylic acids and what are two examples
-COOH OR - CO2H
Ethanoic acid and butanoic acid
What is the condensed formula of carboxylate ions and what is one example
R-COO(-) Sodium ethanoate (CH3COONa)
What is the condensed formula of esters and what is one example
R-COO-R’
Methyl Ethanoate
What is the condensed formula of primary amines and what are two examples
R-NH2
1-butanamine
Methlyamine
For compounds with identical functional groups the boiling point ‘…’ As the length of the chain increases
Increases
Why do boiling points increase As the length of carbon chains increase
As the strength of dispersion forces increase with molar mass, the longer the hydrocarbon chain the stronger the dispersion forces between molecules and higher the boiling point
What is the boiling point of alcohols in comparison to ketones and aldehydes
Alcohols have higher boiling points
Why is the boiling point of alcohols higher than that of ketones and aldehydes
As alcohol can form strong hydrogen bonds with each other due to the polar hydroxyl groups while aldehydes and ketones can only form weaker dipole dipole interactions
What is a carboxylic acid that has the same molecular formula as a group of esters called
Isomeric acid
Is the boiling point of esters of isometric acids lower
Esters
Why is the boiling point of esters much lower than their isometric acid
In the carboxyl groups in carboxylic acids hydrogen bonding can take place as they have C=O and O-H groups while only dipole dipole interactions can occur in esters
Why can’t hydrocarbons soluble in water
They are non polar and like dissolves in like
What is required of polar functional groups form them to form hydrogen bonds with water
The carbon chain they are attached to must be less than 6 carbons long
What happens to the solubility of molecules if there is more than one polar functional group is present
It increases its solubility such as in the case of diols and diamines
Why are some molecules with polar functional groups classified as non Polar
As they have a long carbon chain of 6 carbon atoms or more
Are potassium and sodium carboxylates soluble in water? Why?
Yes, strong ion-dipole bonds form between the negatively charged carboxylate ions and polar water molecules
What’s the general formula for carbohydrates
Cx(H2O)y
What are the simplest carbohydrates and what are two examples
Monosaccharides,
Glucose & Fructose
What is formed when two monosaccharides link together through the loss of a water and what is two examples
Disaccharides sucrose, maltose and lactose
What’s formed when many monosaccharides join together and what’s two examples
Polysaccharides Starch & Cellulose
Reaction for the hydrolysis of polysaccharides to monosaccharides
Starch (C6H10O5)n -H2O & enzyme-> nC6H12O6 Glucose
Reaction for the hydrolysis of disaccharides to monosaccharides
C12H22O11 -H2O & enzyme-> 2C6H12O6
Reaction for the fermentation of glucose to ethanol and carbon dioxide
C6H12O6 -> 2CH2CH2OH + 2CO2
What is the optimum temperature for fermentation and what happens if this the temperature is outside this range
20 & 30 degrees, enzymes will denature if it becomes too hot
What happens if oxygen enters the fermentation vessel
As fermentation is anaerobic process and if oxygen does enter it can bring about the oxidation of ethanol to ethanoic acid
In fermentation should the solution be acidic or alkaline
Acidic
What’s a primary alcohol
An alcohol where the carbon atom the hydroxyl group is bonded to is directly bonded to only one other carbon atoms
Example: Methanol CH3-OH
What’s a secondary alcohol
An alcohol where the carbon atom the hydroxyl group is bonded to is directly bonded to two other carbon atom
Eg: 2-Pentanol
What’s a tertiary alcohols
An alcohol where the carbon atom the hydroxyl group is bonded to is directly bonded to three other carbon atom
Example: 2-methyl-2-butanol
Where do the differences arise in the three classes of alcohols
When they react with oxidising agents
What happens to primary alcohols when they’re oxidised
They form the corresponding aldehyde, if there is continued contact with the oxidising agent the aldehyde is further oxidised to the corresponding carboxylic acid
What happens to secondary alcohols are oxidised
They form the corresponding ketones, does not undergo further oxidation
What happens when tertiary alcohols are oxidised
They are not readily oxidised! Do no react with an acidified dichromate solution
What colour change occurs when primary and secondary alcohols react with potassium dichromate
Orange -> Green however heating is required to observe the colour change at a reasonable time
What’s the difference between aldehydes and ketones
Aldehydes the carboxyl group is in a terminal position
Ketones the carboxyl group is in a non-terminal position
How are aldehydes prepared
The controlled oxidation of primary alcohols
How are ketones prepared
By the oxidation of secondary alcohols, do not undergo further oxidation so the ketone does not need to be distilled off
Equation for the preparation of aldehydes
R-CH-OH –Cr2O7^2-/H+ & Heat–> R-CHO
What happens when aldehydes are heated with an acidified solution of dichromate ions and the relevant half equation
They undergo oxidation to carboxylic acids
RCHO->RCOOH
What is tollens test
Heating aldehydes with ammoniacal silver nitrate solution where they undergo oxidation, under certain conditions can form a silver mirror on the reaction vessel
How can carboxylic acid be prepared
By heating primary alcohols or aldehydes with excess acidified dichromate solution
What do carboxyl acid molecules contain
Carboxyl group -COOH
A carbonyl group and a hydroxyl group attached to the same atom
Ionisation of carboxylic acids in water equation
RCOOH + H2O ->
Neutralisation of carboxylic acid by hydroxide ions
RCOOH + OH^- -> RCOO^- + H2O
Neutralisation of carboxylic acids by carbonate ions
2RCOOH + CO3^2^- -> 2RCOO^- + H2O + CO2
Neutralisation of carboxylic acid by hydrocarbonate ions
RCOOH + HCO3^- -> RCOO^- + H2O + CO2
Are carboxylate salts soluble in water? Why/ why not?
They are soluble in water due to the strong ion-dipole bonds that forms between the negatively charged carboxylate ions and polar water molecules
Why are the structures of aspirin and ibuprofen insoluble, how is this overcome
They have a large non polar component, they are usually mixed with sodium hydrogencarbonate, when mixed with water the the carboxylic group react to form water soluble carboxylate ions
Why are drugs mixed with sodium hydrogencarbonate
The drug becomes easier to administer and faster acting
What’s the difference in structure of esters and carboxylic acids k
The hydrogen atom of the carboxylic acid has been replaced by an alkyl group in the ester
How are esters prepared and what is this known as
Reacting, under reflux, an alcohol with a carboxylic acid in the presence of concentrated sulphuric acid as a catalyst
Esterification
What is reflux and what does this allow
Process by which a mixture of the reactants and products is boiled for a prescribed period of time, allows extended heating of the reaction mixture without loss of reactant and products by evaporation
Two ways to increase the yield of an ester
Use excess alcohol or excess carboxylic acid
Remove water as its formed
What is the hydrolysis of esters
Reverse of esterification where water is consumed as a reactant
Products of hydrolysis of esters in acidic conditions
Carboxylic acid and an alcohol, reaction is catalysed by the acid
Products of hydrolysis of esters in alkaline conditions
Carboxylate ions and an alcohol
As there are ions reaction is irreversible
How are amines classified
Into derivatives of ammonia depending on how many carbons the N is attached to i.e if 1 then is primary
What happens when amine molecules accept a proton
Form a positively charged ammonium ion known as the protonated form of the amine
Are protonated amines soluble in water why/ why not?
Yes, they form strong ion-dipole bonds between positively charged protonated amine ions and polar water molecules
How are drugs with tertiary amine groups usually administered
Water-soluble chloride salts
What’s an amide
A molecule that has an amino group attached to a carboxyl group eg propenamide
Theoretically How could an amide be prepared
A condensation reaction between ammonia or amine with a carboxylic acid
What do Amino acids consist of
At least one amine functional group and one carboxyl functional group with a central carbon Atom,
What is a zwitterion
The result of amino acids undergoing self ionisation where a proton a transferred from the carboxyl group to the amine group in the same molecule
What is formed in nature when a carboxyl group from one amino acid undergoes a condensation reaction with an amine group from another amino acid
A dipeptide joined by a peptide link - forms water too
Result of the continuation of condensation process between two amino acids
Formation of a polypeptide (proteins)
