I need to write about the mechanism and how it happens in this lab please help me explain what happens and how in order for Reduction of 4-Nitrobenzaldehyde to 4-Nitrobenzyl Alcohol and Thin Layer Chromatography 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. 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!)Purification by recrystallization. Take a melting point of your crude product. Read thesection on recrystallization in your lab text before you come to class. Recrystallization isa technique for purification of a solid compound. In general, the compound (and anyimpurities) is dissolved in a minimal volume of hot solvent (or solvent mixture). This hotsolution is left to cool slowly to room temperature, and then placed in an ice bath. Thesolubility of compounds is less in colder solutions, so crystals of compound should formslowly from the saturated solution. (Since the impurity should be present in smallquantities, the impurity will stay in solution while the compound of interest iscrystallizing). If crystal formation is slow enough, the crystal should be pure compound.The purified compound is physically separated from solution by filtration. However, ifthis crystal formation is fast, impurities may be trapped in the rapidly forming lattice ofthe solid crystal. Therefore, it is important to be patient while performing arecrystallization.It may help you to see pictures of a movie of theprocess.Recrystallize the product from methylene chloride, and determine the weight percentagerecovery for this purification step once this purified solid has completely dried. If yourTLC of CP1 or CP2 contained multiple spots, take a TLC of the purified compound bydissolving a few crystals in methylene chloride and eluting with the same solvent asabove (30% ethyl acetate; 70% petroleum ether). Mark this purified product PP.

Question

Accepted Answer

In the above reaction hydroboration takes place where CHO group reduced to -CH2OH.