A) osmium tetraoxide
B) selenium dioxide
C) ammoniacal silver nitrate
D) alkaline permanganate
Correct Answer: C
Solution :
Key Idea (i) Osmium tetraoxide \[(Os{{O}_{4}})\] is most often used for syn-hydroxylation of alkenes. \[C{{H}_{3}}-\overset{\begin{smallmatrix} O \\ | \end{smallmatrix}}{\mathop{C}}\,=C{{H}_{2}}\,\,\,\xrightarrow[{{H}_{2}}{{O}_{2}}/t-BuOH]{Os{{O}_{4}}}\] \[C{{H}_{3}}-\overset{\begin{smallmatrix} C{{H}_{3}} \\ | \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix} | \\ OH \end{smallmatrix}}{\mathop{C}}\,}}\,-C{{H}_{2}}OH\] (ii) Selenium dioxide \[(Se{{O}_{2}})\] is used in the oxidation of \[>CO\] and \[-CHO\] group to 1, 2-dicarbonyl compounds \[C{{H}_{3}}-CHO\xrightarrow{Se{{O}_{2}}}OHC-CHO\] \[C{{H}_{3}}C{{H}_{2}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,=C{{H}_{2}}C{{H}_{3}}\,\,\,\xrightarrow{Se{{O}_{2}}}\] \[C{{H}_{3}}-C{{H}_{2}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\] (iii) Ammoniacal silver nitrate (Tollens reagent) oxidised \[-CHO\] group into \[-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-OH\] group. It is mild oxidising agent. It does not attack the \[>C=C<\] bond. \[RCHO+A{{g}_{2}}C\xrightarrow{\Delta }RCOOH+2Ag\] (iv) Alkaline \[KMn{{O}_{4}}\] 15 used in the hydroxylation of double bond. 1% alkaline \[KMn{{O}_{4}}\] solution is known as Baeyers reagent. \[\begin{matrix} C{{H}_{2}} \\ || \\ C{{H}_{2}} \\ \end{matrix}+{{H}_{2}}O+O\xrightarrow{Alk.\,\,KMn{{O}_{4}}}\begin{matrix} C{{H}_{2}}OH \\ | \\ C{{H}_{2}}OH \\ \end{matrix}\] \[C{{H}_{3}}CH=CH.CHO\] is oxidised to \[C{{H}_{3}}CH=CH.COOH\] by using ammoniacal silver nitrate because in this reaction group is \[-CHO\] oxidised into \[-COOH\] group. \[C{{H}_{3}}CH=CH.CHO+A{{g}_{2}}O\xrightarrow{\Delta }\] \[C{{H}_{3}}CH=CH.COCH+2Ag\]
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