Concept explainers
Interpretation:
The reason for the introduction of an acetal group, mechanism of its synthesis and hydrolysis, conversion of an
Concept introduction:
Acetals are the functional moieties in which a carbon atom is bonded to two oxygen atoms which are then bonded to alkyl chains. These are formed when alcohols react with carbonyl compounds or dihydropyran in an acidic medium or a basic medium. The acetal can be cleaved in an acidic medium to get back a carbonyl compound and an alcohol.
Carboxylic acids undergo reduction in the presence of sodium amalgam, to form alcohols.
Carbonyl compounds are nucleophilic in nature and undergo an addition reaction with
Treatment of
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Organic Chemistry
- A student was given from the list of the conmpounds below A, B and D blindly and asked to identify them all. He treated each of them with Brady's reagent (2,4-ditrophenylhydrazine) and isolated a bright yellow compound for one of them, but the other two gave false negatives. The student reasoned that the false negatives may be due to sterics and, on further thinking, it dawned on him that he might be able to rule out one of the false negatives with the haloform test. What compound did he find compatible with the haloform test? That compound did indeed give a false negative in the Brady test. Which of the other two was positive in the Brady test? A = haloform B = Brady A = haloform D = Brady B = haloform A = Brady B = haloform D = Brady D = haloform A = Brady D = haloform B = Bradyarrow_forward(c) Answer ALL parts (i) to (v). (i) Draw the structure of the enolate ion 5 formed by deprotonation of the ester 4 by the base NaOEt. (ii) Suggest a mechanism for the formation of the enolate 5 and for its reaction with ethanol to produce the diastereoisomeric ester 6. (iii) For each diastereoisomer (4 and 6) draw the two chair conformations (4 chair diagrams in total). (iv) By referring to your chair diagrams, predict which diastereoisomer (4 or 6) will predominate when equilibrium has been reached. (v) What do you think the result would be if the reaction was instead performed using NaOMe in MeOH? NaOEt O H он OEt OEt Ме. Me Ме Ме. Me- Me 4. 9arrow_forward2. (a) Ozonolysis of compound A, C,H12 gave two products B and C. Further analysis of these two compounds of B and C, showed positive results with 2,4-dinitrophenylhydrazine. Compound B reacts with Tollens' reagent while compound C does not indicate any positive result to the same reagent. However, both B and C gave same positive results with iodoform test. (i) By writing all the chemical equations involved, identify A, B and C.arrow_forward
- . (a) Azulene, shown below, has the ability to react with both electrophiles as well as nucleophiles. Use resonance to show how this is possible, indicating in the IUPAC numbering system which C's will react in which way. (b) Hence, write down the product of reaction between azulene and (i) AICI3/CH3COCI. (ii) K* OMe/MeOH. c. What products would you expect from each of the reactions in (b) above if azulene were substituted as follows:arrow_forwarda. sec-butyl alcohol remains optically active in aqueous base, but racemizes when mixed with dilute sulfuric acid. Suggest a mechanism accounting for this observation. b. The following 1935 experiment established that in SN2 reactions, a molecule undergoes an inversion of configuration. Optically active 2-iodooctane was reacted to with Na1311 in acetone. It was observed that the rate of reaction depended on both [RI] and [I-], but the rate of racemization was two times faster than isotopic exchange. Explain this set of results. c. Explain the following observations: (i) why neomenthyl chloride and menthyl chloride yields the following products below; and, (ii) why menthyl chloride reacts 1/200 times as fast as neomenthyl chloride to yield the same product as neomenthyl chloride. da C neomenthyl chloride 2-menthene 25% 2-menthene 75% menthyl chloride 2-menthene only productarrow_forward(a) Give reasons :(i) CH3—CHO is more reactive than CH3COCH3 towards HCN.(ii) 4-nitrobenzoic acid is more acidic than benzoic acid.(b) Describe the following :(i) Acetylation (ii) Cannizzaro reaction (iii) Cross aldol condensationarrow_forward
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- In laboratory, Dr. Nur found out that the hydrolysis of nitriles (R—CN) when heated under reflux with dilute sulfuric acid yielded a major compound A. When compound A reacts with element N it showed that two products are produced (salt and gas). Meanwhile, the reaction of compound A with methanol yielded aromatic scent of compound B. She also noticed two products (compounds C and D) were obtained when she react compound B with reagent Lithium Aluminium Hydride (LiAlH4). Dr. Nur was observed compound C can be prepared naturally in the presence of enzymes in yeast through anaerobic conditions. Further investigation showed when compounds C and D can react with acidified potassium permanganate will produce compound (compounds E and F) with similar functional group. Dr. Nur also discovered compound E will produce silver mirror when react with reagent M and vice versa from compound F. Identify the possible expanded structure of compound A, B, C, D, E and F. Predict the…arrow_forwardConsider the transformation shown in Scheme 1 and answer ALL parts of the question. O (1) (a) Identify reagent X. H i. Reagent X, Et₂0 ii. H*, H₂O Scheme 1 (b) Name compounds (I) and (II). OH (11) (c) Provide a curly arrow mechanism for the transformation in Scheme 1.arrow_forward5. Optically pure 2-octyl sulfonate was treated with varying mixtures of water and dioxane, and the optical purity of the resulting product (2-octanol) was found to vary with the ratio of water to dioxane, as shown in the following table (J. Am. Chem. Soc. 1965, 87, 287-291). Given that dioxane possesses fairly nucleophilic oxygen atoms, provide a complete mechanism that explains the variation in in the product's optical purity due to changes in solvent composition. Hint, the solvent is doing more here than just dissolving.. it is partaking in the reaction. Solvent Ratio (water : dioxane) 25:75 50: 50 75: 25 100 :0 Optical purity of (S)-2-octanol 77% 88% 95% 100% H20 он (R)-2-Octyl sulfonate (optically pure) (S)-2-Octanol (dioxane)arrow_forward
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