Question

1.explain why a single pair product is obtain from hydroboration - oxidation of 2 - butyne, whereas two products are obtained from Hyderabad kitchen of 2 - pentyne

2. the ketone to heptanone has been identified as contributing to the odor of a number of dairy products, including condensed milk and cheddar cheese. describe a synthesis of 2-heptanone from acetylene and any necessary organic or inorganic reagents

Answer 1

Н 2) H2O2; NaOH CH3 1) ВНЗ -CH3 H Cнз Hас- Hас Нас Cнз Нас H-BH2 but-2-yne BH2 ОН butan-2-one 2-butyne is a symmterical alkyne and hence addition of borohydride leads to single isomers and further oxidation gives single enol and respective ketone. Whereas, 2-pentyne is an unsymmetrical alkyne. Hence hydroboration gives two different Н н ketones. CH3 2) H2O2; NaOH HаС 1) ВНЗ HаС "CHз Нас- Нас "СHз CHз ОН pentan-3-one ВН2 ВН2 OH Hас pentan-2-one "CHз "CHз Hас Hас CH3 Н Н

1) ВНЗ 2) Н202; NaOH н,с CH3 1) NaNH2 1) NaNH2 CH3 > Нас ——СH НСCH Нас 2) CH3-Br prop-1-yne 2) n-BuBr heptan-2-one acetylene hept-2-yne Acetylene is methylated first and then n-butylated on the other side using strong base NANH2 and respective alkyl halides. The 2-heptyne is further hydroborated to give desired ketone as one of the major product 3-heptanone is also formed but is in less quantity.