Dibal h nitrile reduction

DIBAL is useful in organic synthesis for a variety of reductions, including converting carboxylic acids , their derivatives, and nitriles to aldehydes . DIBAL efficiently reduces α-β unsaturated esters to the corresponding allylic alcohol. [4] By contrast, LiAlH 4 reduces esters and acyl chlorides to primary alcohols , and nitriles to primary amines [use Feiser work-up procedure]. DIBAL reacts slowly with electron-poor compounds, and more quickly with electron-rich compounds. Thus, it is an electrophilic reducing agent whereas LiAlH 4 can be thought of as a nucleophilic reducing agent.

To be complete, I wasn’t reducing an ester, it was a thioimide. It was an (OH-protected) aldol adduct utilizing a thiazolidinethione as a chiral auxiliary. We developed the conditions for the aldol addition in our laboratory. Suffice it to say we did the diastereoselective aldol addition a lot . Partial reduction of the thioimide to the aldehyde was a common next transformation, so we always had a fresh bottle of DIBAL in the fridge. I reduced 5 different thioimides this way who knows how many times as I ran through the synthetic scheme who knows how many times.

LiAlH 4 contains wt% hydrogen, thereby making LAH a potential hydrogen storage medium for future fuel cell -powered vehicles . The high hydrogen content, as well as the discovery of reversible hydrogen storage in Ti-doped NaAlH 4 , [36] have sparked renewed research into LiAlH 4 during the last decade. A substantial research effort has been devoted to accelerating the decomposition kinetics by catalytic doping and by ball milling . [37] In order to take advantage of the total hydrogen capacity, the intermediate compound LiH must be dehydrogenated as well. Due to its high thermodynamic stability this requires temperatures in excess of 400 °C, which is not considered feasible for transportation purposes. Accepting LiH + Al as the final product, the hydrogen storage capacity is reduced to wt%. Another problem related to hydrogen storage is the recycling back to LiAlH 4 which, owing to its relatively low stability, requires an extremely high hydrogen pressure in excess of 10000 bar. [37] Cycling only reaction R2 — that is, using Li 3 AlH 6 as starting material — would store wt% hydrogen in a single step (vs. two steps for NaAlH 4 which stores about the same amount of hydrogen). However, attempts at this process have not been successful so far. [ citation needed ]

Dibal h nitrile reduction

dibal h nitrile reduction


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