Predict the reagent(s) required to complete the following transformation: 1)O_8O
ID: 994452 • Letter: P
Question
Predict the reagent(s) required to complete the following transformation: 1)O_8O_4; 2)NaHSO_3, H_2O NaNH_2 H_2, Pt Na, NH_3(I) H_2, Lindlar's catalyst Predict the reagent(s) required to complete the following transformation: 1)O_8O_4; 2)NaHSO_3, H_2O 1)Hg(OAc)_2,H_2O; 2)NaBH_4 H_2, Pt 1)9-BBN; 2)H_2O_2, NaOH 1)O_3; 2)DMS Predict the reagent(s) required to complete the following transformation: 1)O_8O_4; 2)NaHSO_3, H_2O 1)Hg(OAc)_2,H_2O; 2)NaBH_4 H_2, Pt 1)9-BBN; 2)H_2O_2, NaOH 1)O_3; 2)DMS What is the common name for the following compound? 1-butoxybutane see-butyl isopropyl ether see-butyl t-butyl ether n-butyl isopropyl ether none of the above What is the IUPAC name for CH_3CH_2OCH_2CH_2CH_2CH_2OCH_2CH_3? 1,4-ethoxyoctane n-butyl isopropyl ether 1, 2-diethoxymethane 1, 2-diethoxyhexane 1,4-diethoxybutane Which one of the following reactions would produce t-butyl methyl ether in high yield? t-butyl chloride+sodium methoxide t-butanol+methanol in presence of H_2SO_4 at 140 degree C t-butyl bromide+bromomethane in presence of NaOH Sodium t-butoxide+bromomethane Predict the product for the following reaction. 3-methyl-3-pentanol 3-ethoxy-3-methylpentane- 3-methyl-2-pentanol 2-ethoxy-3-methylpentane 1-ethoxy-3-methylpentane Predict the product(s) for the following reaction. ethanol+phenol phenol+1-iodoethane iodobenzene+ethanol iodobenzene+1-iodoethane none of theseExplanation / Answer
18. (E) Explanation: Special, partially poisoned catalysts were developed for the selective hydrogenation of alkynes to alkenes. The generally-known Lindlar catalyst, for example, is made up of palladium on a calcium carbonate carrier which is partially poisoned with lead acetate in the presence of amines (e.g. quinoline). The hydrogenation with Lindlar catalyst is a stereospecific cis hydrogenation.
19. (D) Explanation: the reaction sequence of hydroboration, oxidation and hydrolysis of terminal alkynes with a sterically-hindered borane yields aldehyde as the addition HBR2 to an alkyne is a stereospecific cis addition and the boron atom is regiospecifically added to the lower-substituted carbon atom. This is an important difference to the mercury(II)-catalyzed hydration (oxymercuration) in which terminal alkynes are transformed into methyl ketones.
20. (B) Explanation: The hydration of alkynes by oxymercuration yields the Markovnikov enol. f a terminal alkyne is applied, the product of the subsequent tautomerization is a methyl ketone (oxymercuration method).
21. (C) The IUPAC name of the given compound is 2-(tert-butoxy)butane. The principal functional group in this compound is ether linkage and there are two groups attached with either sides of the oxygen - sec-butyl group and tert-butyl group. So, the compound can be called as sec-butyl tert-butyl ether.
22. (E) The IUPAC name of the compound is 1,4-diethoxybutane.
23. (D) The reaction between sodium tert-butoxide and bromomethane goes through an SN2-mechanism. Now, the primary alkyl halide is a very good substrate for SN2 reaction. On the other hand, sodium tert-butoxide is a good nucleophile. So, the reaction would produce the desired product in high yield. In the first case, as tert-butyl chloride is not a good substrate for SN2 reaction due to steric bulkness at the centre carbon, the reaction would not yield the desired product well. In the second case, in the presence of strong Bronsted acid, tertiary carbocation will form from tert-butanol. Now, methanol can attack this cation to form the ether compound, but there will be a side reaction - formation of alkene from the carbocation which would lower the yield of the desired ether product.
24. (B) Explanation: This is an example of alkoxymercuration-demercuration reaction in which the regioselectivity is governed by Markovnikov's rule. The alcohol would attack at the more substituted carbon.
25. (B) Explanation: This is an example of acid-mediated cleavage of ethers. The products will be phenol and 1-iodoethane. Now, as SN2 reaction is not possible on the phenyl ring, even the excess of hydrogen iodide will fail to convert phenol to phenyl iodide as it would have done in case of alcohols bearing alkyl groups.