Why is the solubility of haloalkanes in water very low?
The haloalkanes are only slightly soluble in water. In order to dissolve a haloalkane in water, energy is required to overcome the attractions between the haloalkane molecules and break the hydrogen bonds between water molecules. Since less energy is released in the formation of new attractions between haloalkane and water molecules and these are not very strong as the original hydrogen bonds present in water and hence the solubility of haloalkanes is low.
Match the structures of compounds given in Column I with the classes of compounds given in Column II.
Which of the following compounds will give racemic mixture on nucleophilic substitution by OH ion?
Diphenyls are potential threat to the environment. How are these produced from arylhalides?
Alkyl halides are prepared from alcohol by treating with
(a) HCl + ZnCl2 (b) RedP + Br2
(c) H2SO4 + KI (d) all the above
Draw other resonance structures related to the following structure and find out whether the functional group present in the molecule is ortho, para directing or meta directing.
How can you obtain iodoethane from ethanol when no other iodine containing reagent except Nal is available in the laboratory?
Name the following halides according to IUPAC system and classify them as alkyl, allyl, benzyl (primary, secondary, tertiary), vinyl or aryl halides:
(i)(CH3)2CHCH(Cl)CH3
(ii) CH3CH2CH(CH3)CH(C2H5)CI
(iii) CH3CH2C(CH3)2CH2I
(iv)(CH3)3CCH2CH(Br)C6H5
(v)CH3CH(CH3)CH(Br)CH3
(vi)CH3C(C2H5)2CH2Br
(vii)CH3C(Cl)(C2H5)CH2CH3
(viii)CH3CH=C(CI)CH2CH(CH3)2
(ix)CH3CH=CHC(Br)(CH3)2
(x)P-CIC6H4CH2CH(CH3)2
(xi)m-ClCH2C6H4CH2C(CH3)3
(xii)o-Br -C6H4CH (CH3)CH2CH3
Molecules whose mirror image is non superimposable over them are known as chiral. Which of the following molecule is chiral in nature?
(a) 2-Bromobutane (b) 1-Bromobutane
(c) 2-Bromopropane (d) 2-Bromopropan-2-ol
What are the IUPAC name of the insecticide DDT and benzenehexachloride?
Why is their use banned in India and other countries?
Write structures of the following compounds:
(i) 2-Chloro-3-methylpentane
(ii) 1-Chloro-4-ethylcydohexane
(iii) 4-tert. Butyl-3-iodoheptane
(iv) 1,4-Dibromobut-2-ene
(v) 1-Bromo-4-sec. butyl-2-methylbenzene.
In the following pairs of halogen compounds, which compound undergoes faster SN1 reaction?
Chlorobenzene is formed by reaction of chlorine with benzene in the presence of AlCl3. Which of the following species attacks the benzene ring in this reaction?
(a) CP (b) Cl+ (c) AlCl3 (d) [AlCl4]–
Give the IUPAC names of the following compounds:
(i) CH3CH(CI)CH (Br)CH3 (ii) CHF2CBrCIF (iii) CICH2C=CCH2Br (iv) (CCl3)3CCl
(v)CH3C(p-ClC6H4)2CH(Br)CH3 (vi)(CH3)3CCH=C(CI)C6H4I -p
Toluene reacts with a halogen in the presence of iron (III) chloride giving ortho and para halo compounds. The reaction is
(a) electrophilic elimination reaction
(b) electrophilic substitution reaction
(c) free radical addition reaction
(d) nucleophilic substitution reaction
Questions on the basis of the following reaction:
Which of the following statements are correct about the mechanism of this reaction?
(a) Acarbocation will be formed as an intermediate in the reaction.
(b) OH– will attach the substrate (iii) from one side and Cl– will leave it simultaneously from other side.
(c) An unstable intermediate will be formed in which OH– and Cl– will be attached by weak bonds.
(d) Reaction proceeds through SN1 mechanism.
Alkyl fluorides are synthesized by heating an alkyl chloride/bromide in presence of or
(a) CaF2 (b) CoF2 (c) Hg,F2 (d) NaF
Why is it necessary to avoid even traces of moisture during the use of a Grignard reagent?
Aryl halides are extremely less reactive towards nucleophilic substitution. Predict and explain the order of reactivity of the following compounds towards nucleophilic substitution:
Cyanide ion acts as an ambident nucleophile. From which end it acts as a stronger nucleophile in aqueous medium? Give reason for your answer.
Assertion (A): Presence of a nitro group at ortho or para position increases Reason (R): Nitro gjoup, being an electron withdrawing group decreases the electron density over the benzene ring.
Compound (A) with molecular formula C4H9Br is treated with aq. KOH solution. The rate of this reaction depends upon the concentration of the compound A' only. When another optically active isomer B' of this compound was treated with aq. KOH solution, the rate of reaction was found to be dependent on concentration of compound and KOH both.
(i) Write down the structural formula of both compounds A' and B'.
(ii) Out of these two compounds, which one will be converted to the product with inverted configuration.
Identify the products A and B formed in the following reaction:
CH3-CH2-CH=CH-CH3 + HCl–>A+B
Assertion (A): It is difficult to replace chlorine by -OH in chlorobenzene in comparison to that in chloroethane.
Reason (R): Chlorine-carbon (C – Cl) bond in chlorobenzene has a partial double bond character due to resonance.
Predict all the alkenes that would be formed by dehydrohalogenationof the following halides with sodium ethoxide in ethdnol and identify the major alkene:
(i)1-Bromo-l-methylcyclohexane
(ii)2-Chloro-2-methylbutane.
(ill) 2,2,3-Trimethyl-3-bromopentane.
How the following conversions can be carried out:
(i) Propene to propan-l-ol (ii) Ethanol to but-l-yne
(iii) l-Bromopropane to 2-bromopropane (iv) Toluene to benzyl alcohol
(v)Benzene to 4-bromonitrobenzene (vi) Benzyl alcohol to 2-phenylethanoic acid
(vii)Ethanol to propanenitrile (viii) Aniline to chlorobenzene
(ix)2-Chlorobutane to 3,4-dimethylhexane (x) 2-Methyl-1 -propene to 2-chk>ro-2-methylpropane.
(xi)Ethyl chloride to propanoic acid (xii) But-1-ene to n-butyliodide
(xiii)2-Chlropropane to 1-propanol (xiv) Isopropyl alcohol to iodoform
(xv)Chlorobenzene to p-nitrophenol (xvi) 2-Bromopropane to 1-bromopropane
(xvii)Chloroethane to butane , (xviii) Benzene to diphenyl
(xix) tert-Butyl bromide to isobutyl bromide (xx) Aniline to phenylisocyanide
What happens when .
(i)n-butyi chloride is treated with alcoholic KOH.
(ii)bromobenzene is treated with Mg in the presence of dry ether.
(iii)chlorobenzene is subjected to hydrolysis.
(iv)ethyl chloride is treated with aqueous. KOH.
(v)methyl bromide is treated with sodium in the presence of dry ether,
(vi) methyl chloride is treated with KCN.
Which of the following are secondary bromides?
(a) (CH3),CHBr (b) (CH3)3C CH2Br
(c) CH3CH(Br)CH2CH3 (d) (CH3)2CBrCH2CH3
Assertion (A): In monohaloarenes, further electrophilic substitution occurs at ortho and para positions.
Reason (R): Halogen atom is a ring deactivator.
In the following pairs of halogen compounds, which compound undergoes faster SN1 reaction?
Explain why
(i)the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride?
(ii)alkyl halides, though polar, are immiscible with water?
(iii)Grignard reagents should be prepared under anhydrous conditions?
