I need help explaing how the mechanism works step by step and also shpwing it please from this lab Reduction of 4-Nitrobenzaldehyde to 4-Nitrobenzyl Alcohol and ThinLayer ChromatographyBackground. Oxidation and reduction are among the most common organic reactions,both in the laboratory and in biochemical processes. There are literally dozens ofdifferent methods of oxidizing alcohols to ketones or aldehydes, and almost as many toreduce ketones or aldehydes back to alcohols. In this experiment, we will be using one ofthe most common reducing agents, sodium borohydride, to reduce 4-nitrobenzaldehyde to4-nitrobenzyl alcohol. Note that sodium borohydride is not able to reduce the nitro groupto the corresponding amine. The reaction occurs via a nucleophilic attack of the hydrideon the carbonyl group. (See Karty, Chapter 17, page 821.)H.CH2OHNaBH4(1)NO2When running a chemical reaction, it is important to know when the reaction is complete.This information can prevent you from stopping a reaction too early or wasting timewaiting for a reaction to finish. So how can you easily monitor the progress of thereaction, without using up most of the contents of the reaction mixture for NMRanalyses? By far the most common technique used is Thin Layer Chromatography (TLC).Generally, TLC is a simple, effective and inexpensive method for separating andanalyzing a mixture of compounds (such as the one that may be present half way throughthe reduction) using only a very small amount of the sample – less than a milligram. TLCis a qualitative technique. It does not give you information on how much of a givencompound is in a sample. For details on how Thin Layer Chromatography works, seeyour lab text. You must read this section prior to performing this experiment. Experimental Procedure.You will be using pre-prepared TLC plates and spotters in this experiment.In a small Erlenmeyer flask, dissolve 200 mg (1.30 mmol) of 4-nitrobenzaldehyde in 10ml of methanol.TLC will be used to monitor the progress of your experiment. Prepare a TLC plate sothat two spots will be eluted (Starting material – SM; Crude product 1 – CP1). Spot aTLC with your starting material (SM). The spot of the 4-nitrobenzaldehyde should bereadily visible by UV, since the compound absorbs very strongly in the UV region.Take the sodium borohydride out of the dessicator, quickly weigh out 70 mg of NaBH4,and put the sodium borohydride container back to the dessicator. Add the sodiumborohydride to the Erlenmeyer flask that contains the methanol solution of the 4-nitrobenzaldehyde, with stirring. In your laboratory notebook, record the time of additionof sodium borohydride to your reaction flask. Some of the sodium borohydride might notdissolve in the solution. These particles are an insoluble salt which is a product of thereaction.Now spot your second spot (of the reaction mixture that is stirring in your flasks) on theTLC plate (mark it CP1), and note the time in your lab notebook. While the reactionmixture is stirring, elute the TLC using 30% ethyl acetate in petroleum ether (30% ethylacetate; 70% petroleum ether). Remember to keep the elution solvent below the level ofthe TLC spots when you place the plate in the elution chamber.From this TLC, find out if there is any starting material (4-nitrobenzaldehyde) left in thereaction mixture. If there is none, stop stirring. Your reduction is complete. If there is stilla spot on the TLC due to the starting material, continue stirring for about five minutes,then take another TLC with one spot (mark it as CP2). If the reaction is still not complete,add some more sodium borohydride and continue stirring.After the reaction has been completed, add about 20 mL of methylene chloride(dichloromethane/ DCM), and pour the solution into a separatory funnel. Add 20 mL ofwater to the separatory funnel. Shake and let the aqueous and organic layers separate.Place the organic layer (which layer is that?) with your product in an Erlenmeyer flask.Repeat with another portion of methylene chloride. Combine the organic layers and add adrying agent. Gravity filter the solution into 100 mL pre-weighed round-bottom flask andwash the flask and drying agent with an additional 5mL of methylene chloride, alsofiltered into your round bottom flask. Evaporate the solvent on a steam bath in the hood(Erlenmeyer), or use the rotary evaporator (round bottom flask). Weigh the flask againand calculate the crude yield.(Be sure all solvent has been removed!)

Question

Accepted Answer

Sodium borohydride is An mild reducing Agent whivh converts Aldehydes and ketones to Alcohols.