Exam Technique Flashcards
Why does phenol react more readily with. Hlorined then benzene
3 main points
The lone pair from oh partially delocalised into the system of light bonds
This increases electron density
And so phenol can polarise chlorine more
In comparison to benzene
Why 2-4direcitn have mixture of products
SUBSTITUION AT DIFFRENT PLACES
How to do STRUCTURAL ISOMER QUESTIOSN
Say for c8H10
remember if you add something on the benzene you lose a hydrogen, use this to make sure hydrogen count is correct
Here you know benzne ring will take c6h6, but actually if you add a c then you lose a H, so you can put two Hs extra you thought not before , !!
Showing bro inaction with ohenol what to do?
SHOW THREE BEZNENES ON IT EVEN IF IT DINT MENTION
Remmeber when cyclohexene adds on bromine what it becomes
CYCLOHEXANE!
How to compare resistance of brominatioj what need to say
- cyclohexene electrons are loalcise dso greater electron density
-benzene electrons are delocalised ! (In a CONTINOUS system of pi bonds. Thus electron density is spread out )
- phenol lone pair on O oh OH partially delocalised into pi system to increase electron density co pared to benzene
As cyclohexene and phenol have greater electron density compared to beznene, they can successfully induce a dipole (in whatever ) more / attract electrophile more
Thus addition happens more readily reduces resistance
So localised electrons vs delocalised benzene and partially delocalised
How this changes density
Okay fir makes what to say comparing reavtivitied between ebnende and Alkenes
PI ELEFTROMDNare delocalised for Beinen
And PI a electroms are local sided between 2 carbons in aleken
Thus between 2 carbons Alkenes age more electron density and thus can polarise bromine more and atgrvst the electrophiles
!!pi ELECTROMD
How ti de Sri be structure if benxne with diagram
EXTRA STUFF MAKE SURE INCLUDE
Show diagram either before and after to show pi bonds have overlapped or just draw rings to show
Then say benzene is planar ring 6 carbon 3 electrons et
Last electron sits in p orbialts 90 to plane
These OVERLAP to form a CONTINOUS ring of electron density ABIVE AND BELOW THE RING, forming a system of PI BONDS. Here the ELECTRONS ARE DELOCLAISED
4 things
Overlap
- forming electron density above and below
- forming system of pi bonds
- where electrons are said to be delocalised
2) HERE - ring is planar (got that)
- sigma bonds between cc and ch (got that
- BONDS ARE ALL EQUAL IN LENTGH
- and angles are 120° (as planar)
Extra things to mention in strufture of benzene
Bind angles are 120
And lentgh is the same everyhwere
And planar
And a,so sigma between others
Oh damn if they say suggest anither product likely to be formed in nitration of ohenol what you say
Lie 3 nitro
Or double substituier just something extrem
BEUV MAKE SURE YOU STATE ALL CONDITIONS FOR NITRATION IF BEZNEN VS OHENOL
Benzne = conc nitric cinc sulfuric
AND 50° PLEASE
but phenol just dilute nitric
If an acyl chloride reacts with ohenol what happens?
It’s not ACYLATION, instead it is a NEUTRILISATION REACTION
Explain term delocalised pi bond electrons
INCORRECR
DELOCLAISED electrons are electrons that are spread over MORE THAN TWO ATOMS
And the pi bond bit is that they are FORMED BY AN OVERLAP OF P ORBITALS !
so electrons that are spread across more than 2 atoms where they are formed by an overlap of p orbitals
How to show bromine as an electrophile ?
Show the polar charge
- say it accepts an electron pair if electrophile
- show example from rando reaction
ALSO ANOTHER REASON FIR WHY BEZNENE LESS READILLY RECATS WITH BROMINE COMPARED TO CYCLOHENE (other than the electron density)
ALSO BENZNE MUCH MORE STABLE
- This More Energy needed to react with
If saying write equation and not space then
PLEASE USE LETTERS, especially if it says balance
Remember if yield by max is something and you’re working back need to DIVIDE BY 0.45!OR WHATEVER LERCENTAGE YIELD IS
Name two types of commercially importsnt material whose manufacture involves nitration of benzne
- pharmaceuticals like paracetamol?
- dyes / explosives?
So answer is
- fibres/ dyes/ explosives / Pharma
For nitration what are specific conditions
Coco acids so cinc nitric and conc sulfuric
50
What does curly arrows movement mean
1) movement of a PAIR OF ELECTROND
2) also breaking or forming a covalent bond
Remember key word for definition of electrophile
Accepts a PAIR of electrons
Compare number of electrons and nature in benzne vs horseshoe
When talking about electrons being DELOCLAISED, always mentioN PI BONDING electrons
1) pi bonding electrons are DELOCLAISED in both structured, yet there are 6 complete wlectrons here in first,
- which spread across the ALL CARBON AROMS
x in second there are only 4 delocalised pi electrons , which spread across 5 CARBONS ( giving it listigerem )
so 1) DELOCLAISED 2) how many) 3 where they spread!
How else find rate constant if order 1
You know it’s just any rate / any cknc
So if you found grsdient for first conc then just do one over other
Or find ln 2
For moles, do the correct calc, then multiply by Avogadro to get total formula mass and then compare
Don’t assume the charge on NO2 as +!
Gotta see how many it connect with other ion, here it wa mg so NO2 is -1 and thus N is 3
Remember to check units for the activation energy stuff
So like make sure joule vs kilojoules
How to say order 0 for straight line on comic time growth
Lit jus say it is constant grsifent so zero ordere
Say straight line through 00 correct, also directly proprtionsl and as one increases it increase by same factor
BRUV REMEMBER BALACING YOU ARE ALLOWED HALF NUMBERS
bun that remember thst it should be balanced I’m the first place 😭😭😭 then it will work out
Remember how to find out iverla order if they give units?
Just use units and manipulate snd youll findit
Catalyst added to system in dynamic equilibrium
The rates of friars and backward inc by same amount
Nothing happens to the concentrations!
Two ways a catlayst helps chemical companies make processes more sustainable and less harmful
Can be carried out at lower temperature which means lower energy demand
And thus less fossil fuels burnt and less co2 emissions
And can reduce use of TOXIC SUBSTANCES
Also if it is in the presence of something BUT NOT IN THE EQUATION, can it still pop up in the rate equation?
Yh ti can , make sure to use all evidence they give!
Also why does a large excess of a reactant mean in terms of orders
OR
Most likely that the reactant has no order so haveing large excess means it can be 0 order
Large excess which basically means it’s CONSTANT
OR TO MAKE SURE EQUILIBRIUM POSITION TO THE RIGHT
Whenever get graph and maybe dont knowwhat order is, work out half life if it is a curve
Half life will mean itd 1st
Not means 2nd
Straight means 0
Okay make sure thet if asking in minutes DOMT do conversion
And if they ask for initsl rste snd yiu have rste equation instead of doing tangent business try do
Try do rste formula and substitute in
Damn how to find kc constant if you don’t have VOLUME so can’t find concentrations but still have moles
Well all the volumes say CANCEL out in final division so just do kc but using the moles thstsit
This is because in equilibrium the volume of everything is the same, just different moles?
Chlorine risk and benefit for wwter treatment
BENEDIT = KILLS BACTERUA AND STERILISED WATER
Risk it can run into plants where CAN FORM chlorinate hydrocarbons can be made which are toxic and carcinogens WHEN RUN OFF
Bruv if iodide has higher boiling point and weaker permanent dipole, then the reason for this is because of london firces cmon man
PATRERN how read a few time s
When showing Boltzmann change usijg temperature, what to make sure to do
Right and upwards, mark ea and say popetion ofmmoelcuels with required eamhsd nie increases so rate respirier increases
How to do recrystallisation to obtain pure product
Dissolve it in min volume of hot water
Cool solution and fikter solid
And wash with cold solvent and let it dry
Check its purity by finding melting point
And comparing it against known values
The closed ti is the more pure it is
Trend with mit much actual substance how to shown
Just say this the most this the least reactive or jitrwted
How to say REASON FOR LESS ELECTRON DENSKTY IN DEACTIVATING GROUPS
Say as CooH group is an ELECTRON WITHDRAWING Group , the electron density is lower then BEZNENE so it attracts electrophiles and polarised them less
Phenol partially delocalised increase
Remember Mass of the molecules is what on the mass spectrum
The Peak at the Right the molecular ion so find molecular formula find the percentage empirical snd kultipyl to ger molecular
Why major product formed
Because the carbocations formed forms on the carbon with the most alkyl group as thisnis stable most, thus it happens lket his,
Get this right man what is the weaker base and what can it only react with
The weaker base is the sodium cabrinate so only reacstw ith carbox
Stringer is Na hydrodide and this reacts with BITHN
REMEMBER TO WORK OUT EZ BY DRAWING AND CANCELLING EACH OUT
Oh damn don’t get caught lacking with Ethernet and bromine bonds broken it’s BOTH PINAND SIG,A
!! Because pi bond in Alkenes. And sit,a bond in bromine
Remmeber Potsdoum hydroxide can react with ohenol as neutriksaiton !
SIMILARITY SND DIFFERENC EWITH KEKULE AND DELOCALISED MODEL for overlap
- bith hsve side on overlap of p orbitals to make pi bonds
But BEZNENE has a system kf pi bonds above snd below
Where as kekelule localised
And alternation linbodjs comsore do delocalised drink shdgem around sll 6
So 2) alternating bs sround all
2) bith ive,ap to make pi bonds
One is local one is delocla
Describe 3 evidence
2) bond lemthnall the same
2) hydrogenation less than expected for model
3) benzne is less reactive than Alkenes as brominatioj wouldn’t happen without catalyst
Okay so we got curly arrow moving up to positbe whatnhspoens
Now positbe negative and what was lost 2 so positbe !
Hereltotyic fission
Both electrons go to one
WHEN A COVSLENT BOND BRESKS
Damn add three pronaonesand balance equation ti get same cabrin as before
Scatalsyr is it is produced snd msde so not used up too!
