Read and be familiar with the Semi-Microscale lab procedure. Omit Step 1 \"Recry

Question

Read and be familiar with the Semi-Microscale lab procedure. Omit Step 1 "Recrystallizing benzil" and begin with Step 2 using 1 g of benzil in a 125-mL Erlenmeyer flask. You will assess the purity of your product by obtaining i) an IR spectrum, ii) TIC, and iii) comparing the melting point of your product to the known compounds. Melting points can be used to assess purity (and identity) In a perfect crystal with no impurities the melting point will occur at one temperature However when impurities arc introduced there is no longer a continuous crystal structure. Instead the solid is made up of different regions, some with more crystal imperfections than others This will cause melting to begin earlier than expected and to occur over a longer range of temperatures. Even water or solvent can be an impurity, that is why it's important to make sure the crystals arc dry. Often in an organic chemistry research lab, one will obtain a "co-spot" of the starting material and product on a TLC plate to ascertain if the reaction has gone to completion Prepare your TLC plate as follows: i) In the left-hand lane spot the starting material; ii) In the right hand lane, spot your product: and iii) In the middle spot both starting material and product (on top of each other). What hazards arc associated with the use of the reagents and solvents used in this lab? How will melting point and IR be useful for identifying the product of your reaction? How many moles of ketone or aldehyde can you reduce with one mole of NaBH_4? What changes would you expect lo observe in the 'HNMR and 'CNMR upon reducing a ketone lo an alcohol? What arc the physical property (mp, bp, R_f) differences between two enantiomers? Diastereomers? Meso compounds? What is the relationship between R_f and polarity?

Explanation / Answer

QUESTION 01

The hazards associated with a chemical compound can be found using the Material Safety Data Sheet (MSDS). The hazards associated with benzil and Sodium Borohydride are as follows.

Benzil

Hazardous in case of skin contact (irritant), of eye contact (irritant), of inhalation (lung irritant).

Sodium Borohydride

Extremely hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Very hazardous in case of skin contact (corrosive).

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