Organic Chemistry Flashcards
What does saturated mean?
Contains single carbon bonds only
What does unsaturated mean?
Contains a C=C double bond
What is steroisomerism?
Molecules with the same structural formulae but have different spatial arrangments of atoms
How do you class which atom is the priority group
The atom with the bigger atomic number
When do E Z isomers arise?
When there is restricted rotation around the C=C double bond
and when there are two different groups/isomers attached to both ends of the double bond
How do you identify an Aldehyde and what does its name end in?
It always has a C=O bonf on the first carbon chain so it does not need a number only di or tri. Its name ends in -al.
How do you identify ketones and what is their suffix?
Ketones have 5 carbons or more in a chain then it needs a number to show position, if not it dosent need one. Ketones have double carbon bonded to oxygen on any but the first carbon. Its suffix is -one
How do you identify carboxylix acids in stuctural formulae and what is their suffix?
No number neccesary for this group as it must always be at the end of the chain. It consists of an -OH group and double bond of oxygen attached to the same carbon at the end ends in oic acid
When is the hydrox- prefix used?
When aldehydes and alchohols are in the same molecule, aldehydes take higher priority than alchohols and so the al suffix is used whereas hyrox prefix is used, e.g. 4-hydroxylbunanal
Describe the process of fractional distillation
Oil is pre-heated then passed into column.
The fractions condense at different heights
The temperature of column decreases upwards
The separation depends on boiling point.
Boiling point depends on size of molecules.
The larger the molecule the larger the London forces Similar molecules (size, bp, mass) condense together Small molecules condense at the top at lower temperatures
big molecules condense at the bottom at higher temperatures.
What is cracking?
The conversion of large hydrocarbons to smaller molecules by breaking c-c bonds in thermal decomposition +the production of hydrogen
Describe the economic reason for catalytic cracking
-Shorter chain molecules are more in demand
- Makes use of excess larger hydrocarbons to supply demand for shorter
-Products of cracking are more useful as materials and used as fuel
Why does cracking require high temperatures?
It is a chemical process that nvolves splitting of strong covalent bonds and so requires high temperatures
What does reforming do?
Turns straight chain alkanes into branched and cyclic alkanes and aromatic hydrocarbons
Explain why alkanes are used as fuels?
They readily burn in the prescence of oxygen, This combustion of alkanes is highly exothermic
What would be the physical observation that incomplete combustion has occured?
A sooty flame would be produced
Describe the properties of CO and how it is dangerous to humans
CO is a colourless gas that is toxic to gumans as it can form a strong bond with haemoglobin in red blood cells. This is a stronger bond than made with oxygen s it prevents oxygen attaching to the haemoglobin
What bonds does the double covalent bond in alkenes consist of?
One sigma (o) bond and One Pi bond (π)
Describe makes double covalent bond in an alkene so vunerable to attack by electrophiles
The double covalent bond consists of exposed Pi bonds either side of the bond, Pi bonds have high electron denity makeing them more vunerable to attack
Describe how a sigma bond is formed and the movement around the bond
One sp (squared) orbiatal from each carbon overlap to form a single c-c bond called sigma. Rotation can occur around the bond
Describe the formation of a pi bond ,how it results in it being more subseptible to attack by electophiles, its strength in comparison to the sigma bond and rotation around the bond
The Pi bond is formed by sideways overlap of two P orbiatals on each carbon atom. This forms a Pi bond above and below the plane of the molecule. Because Pi bonds have high electron density, theis leaves bond with high electron density above and below line between two nucleui so eletrophiles are attracted. It sis weaker than the sigma bond and there is restricted rotation aroud the bond
What is an addition reaction?
When two molecules reacts to produce 1
Describe the reagent, condition and type of reaction used to turn an alkene into an alkane
Reagent- Hydrogen
Conditions- Nickel catalyst
Type of reaction- Addition/reduction
Describe what is formed from the reaction of alkenes with bromine/chlorine and the reagent used, conditions, mechanism and type of bond fission
Formed- Dihalegenoalkane
Reagent- Halogen reagent dissolved in organic solvent
Conditions- Room temperature, No UV light
Mechanism- Electrophilic addition
Bond fission- heterolytic
Describe the reaction of hydrogen bromide with alkenes including what type of molecule is formed, the reagent used, the conditions, the type of mecahnism and the type of bond fission
Formed- Halegenoalkane
Reagent used- HCL or HBR (H+ electrophile)
Conditions- Room temperature
Type of mechanism- Electrophillic addition
Type of bond fission- Heterolytic
Describe happens as Br2 approaches the alkene molecule to produce carbocation
The Pi bonds in the electrons reject the electron pair in Br-Br, this induces a dipole making Br2 polar and electrophillic.
Explain why teriary rather than secondary and secondary rather than primary carbocations are more stable than
Because the methyl groups on either side or one side of the positive carbon formed after first bromie/chlorine molecule produces the carbo cation are electreon releasing, reducing the charge on the ion therefore making it more stable.
Describe the reagent,condition,reaction and its observations of an alkene forming a diol diol
Cold KMnO4 in acidified solution at room temperature is added to the alkene which undergoes an oxidation reaction. The purple colour of MnO4 ion is changed from purple to colourless.
Write out the displayed formula of propene reacting to become a diol and name the diol
What is a radical and how is it formed?
It is a species with unpaired electrons that is formed by homolytic fission of a covalent bond and results in the formstion of radicals
Describe another test for alkenes that dosent involve diols
Bromine dissolved in water at room temperature undergoes an addition reaction with alkenes . The porange colour of bromine water will decolourise to colourless
Describe how alkenes form alchohols
They undergo hydration reaction with water in the precence of the acid catalyst- H3PO4 (phosphoric acid) under high temperature(300-600”) and high pressure of 7atm