In the last molecule, after the reduction of the ester by lithium aluminium hydride, the product drawn has fewer carbon molecules than the reactant, mistake maybe? please check it out.
It's true that two carbons were lost, but it's not a mistake. The reaction of esters with LiAlH4 goes a different (though related) mechanism than the reaction with aldehydes/ketones, but it wasn't shown in this video. With and esters, a hydride adds, then an alkoxide is eliminated to produce an aldehyde, then a second hydride adds. In this specific example with an ethyl ester, it will eliminate CH3CH2O(minus) when it forms the aldehyde, before the second hydride is added. After workup, you get the primary alcohol, and the CH3CH2O(minus) will end up as ethanol which is washed away.
In the last molecule, after the reduction of the ester by lithium aluminium hydride, the product drawn has fewer carbon molecules than the reactant, mistake maybe? please check it out.
It's true that two carbons were lost, but it's not a mistake. The reaction of esters with LiAlH4 goes a different (though related) mechanism than the reaction with aldehydes/ketones, but it wasn't shown in this video. With and esters, a hydride adds, then an alkoxide is eliminated to produce an aldehyde, then a second hydride adds. In this specific example with an ethyl ester, it will eliminate CH3CH2O(minus) when it forms the aldehyde, before the second hydride is added. After workup, you get the primary alcohol, and the CH3CH2O(minus) will end up as ethanol which is washed away.