Home /Class 12, Question Bank, Word Problems/ORGANIC WORD PROBLEMS
Arun Kumar Das Gupta
Arun Kumar Das Gupta , populerly know to his students as AKD sir, is a 1 st class M.Sc in inorganic chemistry from Calcutta university. He is also a 1 st class B.Ed from Calcutta university. He is teaching chemistry in secondary and senior secondary level for last 30 years. AKD sir is writer and editor of few books and articles.
Class 12,Question Bank,Word Problems |
ORGANIC WORD
Q.1. An unknown aldehyde (A] on reacting with alkali gives β-hydroxyaldehyde which loses water to form an unsaturated aldehyde but-2-enal. Another aldehyde (B] undergoes disproportionation reaction in the presence of cone. alkali to form products [C] and (D]. The compound (C] is an aryl alcohol with formula C7H8O.
(i) Identify [A] and (B]
(ii) Write the sequence of reactions involved.
(iii) Name the products when (B] reacts with zinc amalgam and hydrochloric acid.
Q.2. An organic compound [A] with molecular formula C5H8O2 is reduced to n-pentane on treatment with Zn-Hg/HCI. The compound [A] forms a dioxime with hydroxyl amine and gives a positive iodoform test and Tollen's test. Identify the compound [A] and deduct its structure.
Q3. An organic compound [A) which has a characteristic odour on treatment with NaOH forms two compounds [B] and [C]. Compound [B} has the molecular formula C5H6O which on oxidation gives back compound [A}. The compound [C] is the sodium salt of an acid [C]. When [C] is heated with sodalime, it yields an aromatic hydrocarbon
[D]. Deduce the structures of [A], [B], [C] and [D].
4. An organic compound 'A' (molecular formula C4H100) reacts vigorously with acetyl chloride and responds to iodoform test. When passed over heated alumina, 'A' is converted into another compound 'B' (C4H8) which upon ozonolysis gives only an aldehyde. Identify 'A' and 'B' with reactions.
5. An alkene [A] on ozonolysis gives acetone and aldehyde. The aldehyde is easily oxidised to acid [B]. When [B] is reacted with bromine in the presence of phosphorus, it yields compound [C] which upon hydrolysis gives hydroxyacid [D]. The acid can also be obtained from acetone by reacting with HCN followed by hydrolysis. Identify the compounds A, B. C and D.
Q6. An aldehyde' A' (C11H5O) which does not undergo self aldol condensation gives benzaldehyde and two moles of 'B' on ozonolysis. Compound 'B' on oxidation with silver ions gives oxalic acid. Identify the compound' A' and 'B'.
Q7 Compound X (C6HIO) gave 2-methylpentane when treated with H2 and Pd. When treated with acid solution of mercury sulphate, it yielded C6HI20. Compound X did not react with ammoniacal Cu2Cl2 or metallic sodium. Suggest the structure X
Q8. An organic compound A with molecular formula C5H8 when treated with sodium in liquid ammonia followed by treatment with n-propyl iodide yields C8HI4(B). When treated with dilute sulphuric acid containing mercuric sulphate, A gives the ketone C (C5H10O). On oxidation with alkaline potassium permanganate B gives two isomeric acids C4H8 02 (D and E) Identify the compounds A to E giving the reactions involved.
Q9 On careful reduction, A(C2H2 ) gives B(C2H4) which reacts with hydriodic acid to give C(C2H5I). A forms a di-sodium derivative which reacts with compound C to give mainly D(C6HIO). With dilute sulphuric acid containing mercuric sulphate D gives E(C6HI20) which reacts with the Grignard derivative of C to give F(C8Hl8O). On oxidation gives G(C3H602) which gives an acid chloride H. The latter reacts with one molecule of the Grignard reagent from C to give I(C5H10O). With two molecules of the same Grignard reagent H gives J(C7HI60). Identify the compounds A to J giving the reactions involved.
Q10 An organic compound A which is a neutral liquid is found to have molar mass of 216 g mor -1. Hydrolysis of the compound A gives an acid B with equivalent mass of 80 g eq-1. B loses carbon dioxide when heated and yields another acid C with equivalent mass of 116 g eq-1. Decarboxylation of C by heating with sodalime yields a hydrocarbon which is identified as as n-pentane. Give the possible structures for .A and B.
Q11 With bromine and caustic potash the straight chain compound C4H90N (A) gives C3H9N(B). With caustic soda it gives C4H702Na (C) and with phosphorus pentaoxide, C4H7N(D). With hydrochloric acid, D gives C4H8O2 of which C is the sodium salt. B may be converted to an alcohol (F) then to a halide. The Grignard reagent from the letter reacts with carbon dioxide to give E. On oxidation F gives successively C3H60(G) and C3H602(H). Identify the compounds A to H.
Q12. An organic compound A(C3H6Cl2) gives with alkali B(C3H60) or C(C3H4). The compound B gives D (C5H12O) with ethyl magnesium iodide. The compound D forms an iodide E. The compound C reacts with dilute sulphuric acid containing mercuric sulphate to give F(C3H60), which gives the salt G(C2H402) with bromine in alkali. The Grignard reagent from E reacts with F to give H(C8H18O). Identify the compounds A to H giving the reactions involved.
Q13 An organic compound A of the formula C2H60 on treatment with concentrated H2S04 gives a compound B(C4H 10O). The latter on treatment with PCl5 gives a product which on subsequent treatment with KCN yields a compound C(C3H5N). The compound C on hydrolysis gives an acid (C3H602) and on reduction with ,sodium amalgam gives a base C3H9N. What are the compounds A, B and C? Also give the reactions involved.
Q14. The compound C8H9CI (A) on treatment with KCN followed by hydrolysis gives B (C9HlOO2). Ammonium salt of B on dry distillation yields C which reacts with alkaline solution of bromine to give C8H11N (D). Another compound E (C8H10 O) is obtained by the action of nitrous acid on D or by the action of aqueous potash on A. E on oxidation gave
F(C8H 6 O) which gives the inner anhydride G on heating. Deduce the structures of A to G giving the reactions involved.
Q15. A substance A shows the following composition: 70.6% carbon, 5.87% hydrogen and 23.5% oxygen. Its vapour density is 68. A when treated with PCI5 and subsequently with NH3 gives a substance B. When reacted with Br2 and KOH, B forms a base C which on diazotization and boiling with water gives a-cresol. What are A. Band C
Q16. A compound A has the molecular formula ClOH1202 and is soluble in aqueous sodium hydroxide but insoluble in ­sodium bicarbonate solution. Treatment of compound A with dimethyl sulphate and aqueous sodium hydroxide gives compound B of molecular formula C11 H1402, while treatment of compound A with strong alkali alone gives an isomeric compound A'. Methyl iodide is formed on refluxing compound A with hydriodic acid. Compound B is insoluble in alkali and decolourises potassium permanganate and bromine; treatment with strong alkali converts compound B to an isomer B'. Ozonolysis of A' gives a compound C of molecular formula C8H803 and isomeric with vaniline. Ozonolysis of compound B' gives a compound D of molecular formula C9H1003 and which is identical with the product of methylation of vaniline. (4-hydroxy-3-methoxybenzaldehyde). Deduce the structures of compounds A, A'. B, B', C and D.
Q.17.An aromatic compound A on treatment with aqueous ammonia and heating forms compound B which on heating with Br2 and KOH forms compound C of molecular formula C6H7N .Write the structures and IUPAC names of compounds A,B,C.
Q.18. An organic compound A with molecular formula C8H16O2 was hydrolysed with sulphuric acid to give a carboxylic acid B and alcohol C. Oxidation of C with chromic acid produced B. C on dehydration gives but-1-ene.Write reactions involved.
Q.19.An organic compound A which has a characteristic odour on treatment with NaOH forms two compounds B and C. Compound B has a molecular formula C7H8O which on oxidation gives back compound A. Compound C is sodium salt of acid. C when heated with sodalime yields an aromatic hydrocarbon D. Deduce structures A-D .
Q.20. A compound 'X' (C2H4O) on oxidation gives 'Y' (C2H4O2). 'X' undergoes haloform reaction. On treatment with HCN 'X' forms a product 'Z' which on hydrolysis gives 2- hydroxy propanoic acid. (i) Write down structures of 'X' and 'Y'. (ii) Name the product when 'X' reacts with dil NaOH. (iii) Write down the equations for the reactions involved.
Q. 21. Primary alkyl halide C4H9Br (a) reacted with alcoholic KOH to give compound (b). Compound (b) is reacted with HBr to give (c) which is an isomer of (a). When (a) is reacted with sodium metal it gives compound (d), C8H18 which is different from the compound formed when n-butyl bromide is reacted with sodium. Give the structural formula of (a) and write the reactions for all.
Q.22. An organic compound (A) with molecular formula C8H8O forms an orange-red precipitate with 2,4-DNP reagent and gives yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens' or Fehlings' reagent, nor does it decolourise bromine water or Baeyer's reagent. On drastic oxidation with chromic acid, it gives a carboxylic acid (B) having molecular formula C7H6O2. Identify the compounds A and B and explain the reactions involved.
Q.23 . An organic compound with the molecular formula C9H10O forms 2,4-DNP derivative, reduces Tollens' reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.
Q.24.A compound 'X' (C2H4O) on oxidation gives 'Y' (C2H4O2). 'X' undergoes haloform reaction. On treatment with HCN 'X' forms a product 'Z' which on hydrolysis gives 2- hydroxy propanoic acid. (i) Write down structures of 'X' and 'Y'. (ii) Name the product when 'X' reacts with dil NaOH. (iii) Write down the equations for the reactions involved. [3]
Q.25. With bromine and caustic potash the straight chain compound C4H90N (A) gives C3H9N(B). With caustic soda it gives C4H702Na (C) and with phosphorus pentaoxide, C4H7N(D). With hydrochloric acid, D gives C4H8O2 of which C is the sodium salt. B may be converted to an alcohol (F) then to a halide. The Grignard reagent from the letter reacts with carbon dioxide to give E. On oxidation F gives successively C3H60(G) and C3H602(H). Identify the compounds A to H.
TAGS: Aldehyde Alkene Alkyne Amines Iodoform Ketones Word problems
Devdip Dutta says:
AKD SIR,
I am Devdip from class 12 S1
will you discuss these problems in our class on thursday ??
http://www.blackberry8800series.co.uk/best-pdf-to-word-converter/icrecream-pdf-converter-review says:
Thank you for the great post
I must get across my admiration for your generosity supporting individuals who actually need assistance with that area of interest. Your real commitment to passing the message up and down has been incredibly informative and have all the time permitted those like me to achieve their endeavors. Your entire invaluable advice implies this much to me and far more to my office workers. With thanks; from all of us.
My husband and i ended up being absolutely fulfilled when Raymond managed to do his web research via the precious recommendations he got through your web pages. It is now and again perplexing just to find yourself giving freely thoughts that people today may have been making money from. And we all recognize we need the blog owner to appreciate for this. The main explanations you've made, the straightforward web site navigation, the friendships you can make it possible to promote – it's everything unbelievable, and it's assisting our son in addition to us know that this content is interesting, which is very fundamental. Thanks for all!