(a) (i) Aldehydes are more reactive than ketones due to the following two reasons : (ii) The release of a proton from carboxylic acid is much easier than phenols because carboxylate ion is much more resonance stabilized than phenoxide ion. (ii) Benzaldehyde and acetophenone : (i) p-Methylbenzaldehyde (ii) 4-Methylpent-3-en-2-one (b) How will you bring about the following conversions? (a) (i) Ethanol to 3-hydroxybutanal : Question 55. Add I2 and NaOH in both the solutions. (Comptt. (a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an aldehyde or a ketone. IUPAC name : Pent-2-enal, Question 9. (ii) Tollen’s Test: Benzaldehyde and acetophenone can be distinguished by the Tollen’s test. (i) HCN (ii) H2N – OH (iii) CH3CHO in the presence of dilute NaOH (Comptt. (iii) Pentan-2-one and Pentan-3-one (Comptt. The reaction is known as decarboxylation. (a) Give chemical tests to distinguish between (All India 2010) Give the structure and IUPAC name of the product formed when propanone is reacted with methylmagnesium bromide followed by hydrolysis. Warm each organic compound with I2 and NaOH solution. (c) Out of CH3CH2 – CO – CH2 – CH3 and CH3CH2 – CH2 – CO – CH3, which gives iodoform test? C = But-2-enal. Write the structural formula of 1-phenylpentan- 1-one. Answer: Question 33. (b) (i) Benzoic acid and Phenol : On addition of NaHCO3 to both solutions carbondioxide gas is evolved with benzoic acid while phenol does not form CO2. Hydride transfer reagents, such as NaBH4 and LiAlH4, are widely used in organic chemistry,[11][12] primarily in the reduction of carbonyl compounds to alcohols. Question 78. In basic medium OH- will attack carbonyl group. The reduced fluid can also carry uranium-bearing minerals. Answer: Question 83. Ultimately glucose undergoes oxidation to CO2 and H2O. Answer: Question 69. Write the IUPAC name of the following: (Comptt. Compound ‘C’ is the sodium salt of the acid. A common application of cathodic protection is in galvanized steel, in which a sacrificial coating of zinc on steel parts protects them from rust. The process of electroplating uses redox reactions to coat objects with a thin layer of a material, as in chrome-plated automotive parts, silver plating cutlery, galvanization and gold-plated jewelry. All India 2013) (b) (i) Due to much stronger I-effect of F over Cl, the FCH2COO– ion is much more stable than ClCH2COO– ion and hence FCH2COOH is a stronger acid than ClCH2COOH. (a) Carboxylic acid is a stronger acid than phenol because: [15][16] For example, a reagent that is oxidized loses electrons; however, that reagent is referred to as the reducing agent. Formaldehyde does not contain a-hydrogen atom. Question 106. (a) Describe the following giving linked chemical equations : Answer: (a) (i)Phenol and Benzoic acid: On addition of NaHCO3 to both solutions carbon dioxide gas is evolved with benzoic acid while phenol does not form CO2 (Comptt. And, because it "accepts" electrons, the oxidizing agent is also called an electron acceptor. (Comptt. Answer: IUPAC name : 2-methypropanal. (Comptt. (ii) 4-Methoxybenzoic acid < Benzoic acid < 3, 4-Dinitro benzoic acid. Compound (C) when heated with soda lime yields an aromatic hydrocarbon (D). (All India 2014) (i) Cannizzaro reaction (ii) Decarboxylation (i) Clemmensen reduction Question 67. (a) Give reasons : As a result, simple half-reactions cannot be written for the individual atoms undergoing a redox process. (i) Cross aldol condensation (ii) Decarboxylation alkali and produce alcohol and carboxylic acid salt. (i) Acetophenone and benzaldehyde Question 14. (i) CH3CO(CH2)4CH3 (ii) Ph — CH = CH — CHO (iii) On adding NaHCO,, benzoic acid produces brisk effervescence of C02 gas whereas ethylbenzoate does not. Exercise 5. Question 90. (b) (i) Ethanal and Propanal : Ethanal and propanal can be distinguished by iodoform test. Delhi 2012) Give a chemical test to distinguish between Benzoic acid and Phenol. (ii) Benzaldehyde and Acetophenone (Delhi 2010) What type of aldehydes undergo Cannizaro reaction? [citation needed], Though sufficient for many purposes, these general descriptions are not precisely correct. Draw the structure of 3-methylbutanal. Write one usefulness of this reagent. (b) Complete each synthesis by giving the missing material, reagent or products : (Delhi 2009) (a) Give chemical tests to distinguish between compounds in the following pairs of substances : (i) Ethanal and Propanal (ii) Benzoic acid and Phenol (Delhi 2013) Acetophenone-yellow precipitates of iodoform are formed. Write the equations involved in the following reactions: (ii) It forms a 2, 4-DNP derivative and reduces Tollen’s reagent. (ii) Decarboxylation reaction (Delhi 2017) Give the chemical equations involved. (ii) Decarboxylation using soda lime. "RED CAT" and "AN OX", or "AnOx RedCat" ("an ox-red cat") — reduction occurs at the cathode and the anode is for oxidation, "RED CAT gains what AN OX loses" – reduction at the cathode gains (electrons) what anode oxidation loses (electrons), "PANIC" – Positive Anode and Negative is Cathode. Write the structure of 4-chloropentan-2-one. (i) Out of these compound which gives iodoform test. (i) Ethanal and Propanal (ii) Benzaldehyde and Acetophenone Aldehydes with a hydrogen atom undergo Aldol condensation. (All India 2014) (ii) Phenol and Benzoic acid: On addition of NaHCO3 to both solutions carbondioxide gas is evolved with benzoic acid while phenol does not form CO2. (b) An organic compound contains 69.77% carbon, 11.63% hydrogen and rest oxygen. Tollen’s reagent and undergoes Cannizzaro’s reaction. (iv) ‘A’ on treatment with I2/NaOH gives yellow ppt (Delhi 2012) C8H1602 upon hydrolysis with dil. Cellular respiration, for instance, is the oxidation of glucose (C6H12O6) to CO2 and the reduction of oxygen to water. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions. (a) Account for the following : Answer: (i) C6H5COCH3 < CH3COCH3 < CH3CHO Write chemical equations for all reactions taking place. of cuprous oxide is obtained while propanone does not respond to test Benzaldehyde does not respond to this test. Because there is no net change in charge during a redox reaction, the number of electrons in excess in the oxidation reaction must equal the number consumed by the reduction reaction (as shown above). IUPAC name : 2-methylcyclohexanone. Delhi 2016) (i) Cannizzaro’s reaction (i) Benzene amide and 4-aminobenzoic acid (ii) Methyl acetate and Ethyl acetate Question 72. (a) Give chemical tests to distinguish between the following pairs of compounds : (a) (i) Propanone to Propan-2-ol Answer: Answer: Ammonical silver nitrate solution is called Tollen’s reagent. (b) (i) Pentan-2-one and Pentan-3-one In general, for reactions in aqueous solution, this involves adding H+, OH−, H2O, and electrons to compensate for the oxidation changes. (b) (i) Wolff-Kishner reduction reaction : The reduction of aldehydes and ketones to the corresponding hydrocarbons by heating them with hydrazine and KOH or potassium tert-butoxide in a high boiling solvent like ethylene glycol is called Wolff-Kishner reduction. (iii) It does not reduce Tollen’s reagent so it is not an aldehyde. (Delhi 2012) (i) Propanone oxime (ii) Semicarbazone of CH3CHO Answer: Question 36. (iii) Phenol and Benzoic acid (All India 2009) Antoine Lavoisier demonstrated that this loss of weight was due to the loss of oxygen as a gas. Answer: Write IUPAC name of the following : (Comptt. Question 96. Question 10. (c) Why carboxylic acid does not give reactions of carbonyl group? The word "redox" was first used in 1928. Furfural formation Enolization Oxidation Reduction Osazone formation 43. (iii) Because of smaller +1 effect of one alkyl group in propanal as compared to larger + I effect ol 2 alkyl groups of propanone, the magnitude of positive charge on the carbonyl carbon is more in propanal than propanone. t – butyl alcohol is readily oxidsing in acidic solution (K 2 Cr 2 O 7 / H 2 SO 4) to a mixture of a ketone and an acid each containing lesser number of carbon atoms than the original alcohol. This catalytic behavior has been described as a futile cycle or redox cycling. (i) Propanone to propane (ii) Benzoyl chloride to benzaldehyde (a) State and illustrate the following : Answer: Question 98. Answer: All India 2015) (a) How will you carry out the following conversions? (a) Describe the following giving chemical equations : This results in reduced oxidation of acetyl-CoA in the TCA cycle and the re-oxidation of reduced NADH and FADH 2 via the oxidative phosphorylation pathway. (i) Propanal and Propanone, (ii) Benzaldehyde and Acetophenone. Answer: IUPAC name : 4-Hydroxypentan-2-one, Question 30. Answer: Substances that have the ability to reduce other substances (cause them to gain electrons) are said to be reductive or reducing and are known as reducing agents, reductants, or reducers. Answer: (ii) KMnO4 (Alkaline Potassium Permanganate). (a) (i) Benzaldehyde from Phenol. Due to smaller +1 effect of one alkyl group in aldehydes as compared to larger +1 effect of two alkyl groups, the magnitude of positive charge on the carbonyl carbon is more in aldehydes than in ketones. (All India 2014) Example : Question 65. Further since oxidation of (C) with chromic acid produces the acid (B), therefore both the carboxylic acid (B) and the alcohol (C) must ’.contain the same number of carbon atoms. (i) Propanal and Propanone (ii) Acetophenone and Benzophenone Question 50. Answer: of cuprous oxide is obtained while propanone does not respond to test. (i) Butanal and Butan-2-one (ii) Benzoic acid and Phenol (All India 2017) p-methylbenzaldehyde. All India 2013) (i) Acetylation (ii) Cannizzaro reaction (iii) Cross aldol condensation (Comptt. (a) Mechanism of a nucleophilic attack on the carbonyl group Question 17. Example : (a) (i) Cannizzaro reaction. (Delhi 2013) Answer: anhydrous aluminium chloride (AlCl3) which acts as a catalyst. (a) Give chemical tests to distinguish between the following pairs of compounds : As a result nucleophilic addition reactions occur more readily in aldehydes than in ketones. (i) Electrophilic substitution in Benzoic acid takes place at meta position. (a) Write the products of the following reactions : Question 64. Answer: Answer: Draw the structure of 2-methylbutanaI. For example, during the combustion of wood with molecular oxygen, the oxidation state of carbon atoms in the wood increases and that of oxygen atoms decreases as carbon dioxide and water are formed. (a) (i) Aldol condensation : Two molecules of aldehydes or ketones condense in presence of a dil.alkali to form a β-hydroxy aldehyde or β-hydroxyketone respectively. (b) Write simple chemical tests to distinguish between the following pairs of compounds (i) Cl – CH2COOH is a stronger acid than CH3COOH. (a) (i) Acetylation: The addition of acyl (-COCH3) group on the ortho and para positions of acyl halide in the presence of a Lewis acid i.e. Oxidation of (C) with chromic acid also produced (B). Add ammonical solution of silver nitrate to both the compounds, HCOOH gives silver mirror but CH3COOH does not (iii). (a) Write the chemical equation for the reaction involved in Cannizzaro reaction. Propanone on reacting with I2 and NaOH gives a yellow ppt of iodoform but propanal does not respond to this test. (Comptt. Give an example of the reaction in each case. (ii) Benzaldehyde and acetophenone : (Comptt. Question 58. Write the reactions involved in the following: The second step, which also occurs in the mitochondrial matrix, involves the oxidation of acetyl-CoA to CO 2 … Write the IUPAC name of the compound. (ii) Benzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength) Answer: (a) Give chemical tests to distinguish between (i) Benzoic acid and Phenol (ii) Propanal and Propanone. Yes, it is possible. (b) How are the following conversions carried out? Delhi 2013) Illustrate the following reactions giving a suitable example for each. of a proton easier. Answer: Question 51. Aldehydes and Ketones have lower boiling points than corresponding alcohols. The net reaction is the oxidation of the flavoenzyme's coenzymes and the reduction of molecular oxygen to form superoxide. (iii) Phenol and Benzoic acid (Delhi 2012) Answer: The shift from fatty acid oxidation and glycolytic oxidation, as well as amino acid metabolism, occurs when the need for energy diminishes. The term "hydrogenation" could often be used instead of reduction, since hydrogen is the reducing agent in a large number of reactions, especially in organic chemistry and biochemistry. (a) Arrange the following compounds in an increasing order of their indicated property : Electron donors can also form charge transfer complexes with electron acceptors. Ethanol: Ethanol does not form silver mirror with Tollen’s reagent. Since the — COOH group in benzene is an electron withdrawing group, therefore it is meta directing group. (Delhi 2009) (i) Acetaldehyde, Acetone, Methyl tert-butyl ketone (reactivity towards HCN) (All India 2009) (a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an aldehyde or a ketone. (i) Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength) (a) Give chemical tests to distinguish between the following : Thus one sulfur atom is reduced from +2 to 0, while the other is oxidized from +2 to +4. Formic acid is the only acid which contains aldehydic group and thus shows reactions with Tollen’s reagent (silver nitrate) and Fehling’s solution which Acetic acid does not show. Question 89. of cuprous oxide is obtained while propanone does not respond to test. (c) CH3CH2 – CH2 – CO – CH3 gives Iodoform test. Its functional isomer A will be propanal. Compound (B) has the molecular formula C7H8O which on oxidation with CrO3 gives back compound (A). [3] The chemical species from which the electron is removed is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. Answer: Question 49. Question 101. On vigorous oxidation it gives 1, 2-benzenedicarboxylic acid. (ii) Aldol condensation: Those aldehydes and ketones with atleast one a-hydrogen atom condense together in presence of dil. Many important biological processes involve redox reactions. Rearrange the following compounds in the increasing order of their boiling points: (All India 2013) (iii) Benzoic acid from Ethylbenzene? (c) In FCH2—COOH fluorine is more electron withdrawing than chlorine in ClCH2– COOH so FCH2 – COOHis more acidic than ClCH2—COOH, hence its pKa value is lesser than ClCH2COOH. Write the structure of p-Methylbenzaldehyde molecule. of iodoform but benzaldehyde does not. An aerobic oxidation of primary and secondary alcohols to aldehydes and ketones using TEMPO-CuCl as catalyst in the ionic liquid [bmin][PF 6] … By Iodoform test: Ethyl benzoate on boiling with excess of NaOH solution gives ethyl alcohol which on heating with iodine gives yellow ppt. By Iodoform test: Acetophenone being a methyl ketone on treatment with I2 and NaOH (NaOI) undergoes iodoform test to give yellow ppt. (i) Benzoic acid and Ethyl benzoate, (ii) Benzaldehyde and Acetophenone. Question 4. Elements, even in molecular form, always have an oxidation state of zero. Answer: The reverse reaction, respiration, oxidizes sugars to produce carbon dioxide and water. (iii) Bromobenzene to benzoic acid (All India 2010) (a) Draw the structure of the following : The catalytic hydrogenation reaction is an important industrial process. Write the structure of 3-methyl butanal. Since the — COOH group in benzene is an electron withdrawing group, therefore it is meta directing group. Redox reactions are characterized by the actual or formal transfer of electrons between chemical species, most often with one species (the reducing agent) undergoing oxidation (losing electrons) while another species (the oxidizing agent) undergoes reduction (gains electrons). These metals donate or give away electrons relatively readily. (i) Rosenmund reduction (ii) Cannizzaro’s reaction (a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an aldehyde or a ketone. (iii) Benzoic acid and Ethyl benzoate (Comptt. Ethyl alcohol and 2( methyl alcohol gives haloform reaction. Answer: On addition of NaHCO3 to both solutions carbon dioxide gas is evolved with benzoic acid while phenol does not form CO2. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes, respectively, when they occur at electrodes.