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http://www.chemguide.co.uk/organicprops/arylhalides/reactions.html
for hydrolysis of haloarenes
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reaction will be faster if the electronegativity difference is greater. The slight positive charge on the carbon will be larger if it is attached to a chlorine atom than to an iodine atom.
That means that there will be more attraction between a lone pair on the water and a carbon atom attached to a chlorine atom than if it was attached to an iodine atom.
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sorry can't edit the above post, as the format is out of place
so the factor of weaker bond strength (as in C-I) , is more significant than the factor of the more electron deficient(and hence magnitude of partial +ve charge) on the C atom attached to Cl, and hence rate of hydrolysis of R-I is greater than R-Cl?
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Originally posted by Flying grenade:
sorry can't edit the above post, as the format is out of place
so the factor of weaker bond strength (as in C-I) , is more significant than the factor of the more electron deficient(and hence magnitude of partial +ve charge) on the C atom attached to Cl, and hence rate of hydrolysis of R-I is greater than R-Cl?
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yet another factor favouring hydrolysis of SiCl4 greater than CCl4 ?
delta +ve on Si greater than C. bond str Si-Cl > C-Cl. but SiCl4 much higher propensity to be hydrolysed
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Originally posted by Flying grenade:
yet another factor favouring hydrolysis of SiCl4 greater than CCl4 ?
delta +ve on Si greater than C. bond str Si-Cl > C-Cl. but SiCl4 much higher propensity to be hydrolysed
Minor contributive point. Doesn't make it to the top 3 reasons.And instead of overthinking and obsessing over conceptual stuff like these (which the rest of the Singapore JC cohort just memorize and move on, efficiently albeit blindly ; your desire to focus more deeply on understanding is commendable and serves you well up to a certain easy-to-accidentally-pass point, beyond which being anally obsessive is like missing the forest for the trees, allowing you to win the battle but lose the war), and you J2 students really ought to be practicing as many Prelim papers as you can right now. You'll be far better off (as far as your A level results and hence the quality of the rest of your life are concerned) focusing on doing and asking about Pelim paper qns here, instead of OCDing about conceptual ideas too much.
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Thanks Ultima
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https://en.m.wikipedia.org/wiki/Williamson_ether_synthesis
page 145 mindmap of haloalkanes
btm of page
Williamson's synthesis of asymmetric ethers
george chong forgot to insert the O atom
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page 143 btm of page
CN is substituted, not Br. typo error.
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page 112
does george chong meant lp shld reside in unhybridised p orbital? not sure why he made the mistake 3 times in one page.
what's the hybridisation of O and N? is it sp for O, Sp2 for N?
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pg 145 Nu sub of RX to amine, excess conc NH3, heat in sealed tube. George chong says sealed tube to create high pressure?
sealed tube to prevent NH3(g) from escaping
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then for other gaseous reagents, e.g. Cl2 or H-Cl, no need sealed tube?
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https://www.dropbox.com/s/a3pr13zfs37qway/20160821_101651-1.jpg?dl=0
this molecule can have cis trans?
the first and last molecule
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pg 147, part c
last molecule shld be propylamine, G.C. made a typo error, didn't replace CN with NH2
im paying it forward by helping proof read
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ethane-1,2-diol can be synthesised by ethene->(Cl2 in CCl4) 1,2-chloroethane -> (aq NaOH,heat) ethane-1,2-diol
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page 152
C2H5O- more bulky than C2H5OH, and hence makes SN2 more difficult, lmao? how does one less H makes more bulky, and how does SN2 gets impeded?
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Hi UltimaOnline,
I've a few questions here to consult you.
Q1: IJC/09/P1/39
In which sequence are the compounds listed in order of increasing ease of hydrolysis?
Choice 3 (chlorobenzene, chloromethane, chloroethane) is not a correct choice.
Remarks: In ascertaining the ease of hydrolysis, I'll first have to see the C-X bond strength. Since it's the same in this choice, I'll have to consider either (I) Resonance within the reactant and (II) stability of the intermediate products.
In this case, shouldn't 3 also be correct? What's the difference in the electron donating effect between the methyl and ethyl substituent?
Q2: In relation to VJC/09/P1/29:
Remarks: How do I establish the relative acidity of an alcohol (CH3CH2OH) to that of an acidic salt (CH3CH2NH3+Cl-)?
Q3: VJC/09/P1/23
Remarks: It must have been my blind spot, but why is A not an acceptable answer as well?
Thank you very much Ultima!
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chemguide didn't address why rxn rates of 3° is faster than 1°. the example provided consists of equal no. of C atoms
would be interested to know the difference in the rate of hydrolysis of chloromethane and chloroethane also
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pg 161 , example 6.12 qn incomplete, solution is complete
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when will O and N be sp2 and sp3 hybridised?
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2008 p2 qn 1
noradrenaline qn
qn : draw the pdt when noradrenaline reacts with bromine dissolved in a suitable solvent
super open to interpretation?
if Br2 dissolve in water, will have multi sub
if Br2 dissolve in CCl4, will have mono sub
pls take a look at pg 233 of organic made easy book, therein writes Br2 in CCl4 will only have mono substitution. Thanks ultima.
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2008 p2 qn1
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Originally posted by Flying grenade:
2008 p2 qn 1
noradrenaline qn
qn : draw the pdt when noradrenaline reacts with bromine dissolved in a suitable solvent
super open to interpretation?
if Br2 dissolve in water, will have multi sub
if Br2 dissolve in CCl4, will have mono sub
pls take a look at pg 233 of organic made easy book, therein writes Br2 in CCl4 will only have mono substitution. Thanks ultima.
If you're a BedokFunland JC student, you'll be exam-smart enough to write out both answers, with qualifications, ie. "If this solvent is used, this product is obtained ; if that solvent is used, that product is obtained". Cambridge examiner will exclaim, "Excellent student! Must be BedokFunland JC!" -
Originally posted by UltimaOnline:
If you're a BedokFunland JC student, you'll be exam-smart enough to write out both answers, with qualifications, ie. "If this solvent is used, this product is obtained ; if that solvent is used, that product is obtained". Cambridge examiner will exclaim, "Excellent student! Must be BedokFunland JC!"ok nice, thanks !!