Qn(s) frm one of the OrG. tests here.
1) Among the following which is highly acidic?
3-hydroxy Benzoic acid
2-hydroxy Benzoic acid
4-hydroxy Benzoic acid
a) 3>1>2
b) 2=1>3
c) 1>2>3
d) 1>3>2
( ANs: d... explanation: Ortho effect is not applicable fr phenol. But,, yahaan pe toh -COOH ki acidity ki baat ho rahi hai naa ki -OH waale HYdrogen ki)
Q2) No Prob Here
Assertion - IN 2- NITRO CHOLORO BENZENE THE AROMATIC NUCLEOPHILIC SUBSTITUTION TAKES PLACE
Reason1: DUE TO ELECTRON WITHDRAWING GROUP
Reason 2: DUE TO ELECTRON RELEASING GROUP
W: ASSR IS RIGHT and 1,2,CORRECT EXPLANATION
X: ASS IS RIGHT 1 IS CORRECT ,2 IS WRONG
Y: ASS IS RIGHT , 1,2, IS NOT A CORRECT EXPLANATION
Z: ALL THREE STATEMENTS ARE WRONG [hide
Q3) dipole moment of HCl, HF bond length of HCl, HF
a) 1>2 2>1
b) 2>1 1>2
c) 1>2 1>2
d) 2>1 2>1
(Ans: a)...matlab bond length HF gr8ter than HCl...yeh sahi hai ?)
Q4)CycloPenatanol + P → a four membered ring.
P is-
a) H2SO4
b) KMnO4
c) K2Cr2O7
d) heat@1000k
(Ans: a)...saying tht eliminated product banega....but why will we make a 4-mem. ring..?)
39Avik...in Q1 -OH is not a bulky enough group that it will force the ortho effect into place. Chelation aur ortho effect alag hain..
which you have so graciously stated in your hidden posts :P
In Q2, X is the correct statement.
Yaar in Q3...Cl ka size zyaada hai toh HCl ka bond length HF se zyaada nahi hona chaiye?
Don't know why ring contraction should even happen in that case...there were some exceptions to Cannizzaro reaction which I remember caused ring contraction. Why would it slip down to 4 member when 5 member is more stable?
131) But,,, i was taught,,,tht due 2 ortho eff.in Benzoic Acid....if any group is attached at Ortho (any group), its acidity wud increase.
& Pritish, Then toh agar Cl/Br/CN bhi hoga toh bhi koi effect nahi hona chahiye....??
2) Meri hidden reasoning toh padho..
3) I think same.
39Haan Avik those are not bulky groups. Ortho effect is not applicable for them....I read this on yahoo answers..the guy who answered was finishing his PhD in chemistry.
http://answers.yahoo.com/question/index?qid=20071012080118AABWL03
Zaahir si baat hai ki the group has to be bulky. It forces carboxyl group out of the plane.
Avik mere pyaare, dulaare, pinku, chintu, etcetc bhai....do NOT compare SNAr to EAS. Never. Comparing those two on the same basis is nothing but a crime which makes you liable to the CID.
What prevents SN in aryl substrates? Their delocalised electron density. What reduces this density? Deactivating groups. Will substitution become easier? YES.
All SNAr needs is a leaving group and something which reduces its electron density, making approach of nucleophile easier. Capiche?
And you were asking on chat about terminal alkynes giving Tollen's test. Actually baat yeh hai ki terminal alkyne mein removable hydrogen hota hai. This is replaced by metal atom in acid base type reaction. It gives a ppt of metal acetylide.
For eg, ethyne reacts with tollen's reagent to give AgC(triple)CAg, which has a yellow colour(not sure about the colour).
13Abhi maine ^^^Essay padha nahi,,,
But see one thing, am only saying to see-
o-Hydroxy benzoic acid (pKa 2.98)> m-hydroxybenzoic acid (pKa 4.08)> Benzoic acid (pKa4.20) > p-hydroxy benzoic acid (pKa 4.58)
[3]...Ye ultimate Confirmation Technique hai...[3]
13Fr 2) :O U picked it right....I was Thinking of EAS all this while.
Thnx...(Lekin itna bada essay likhne ki zaroorat nahi thi :P)
(btw whts "Capiche"..?)
& "Paste" ka woh matlab nahi tha :)
39lola...phir toh OH ka asar pad raha hai...lekin halogens mein asar nahi pad raha tha!
I didn't paste. I wrote it.
Capiche means understand in italian :P
13Chloro Derivatives of Benzoic ACid mein bhi asar pad rahaa hai.
See the pKa Values-
o-Cl-BenzoicAcid (2.92), meta-derivative (3.8), para derivative (3.98)
39Hmm..achcha that comparison was between fluoro and chloro benzoic acids.