CHE 211 Study Guide - Midterm Guide: Partition Coefficient, Solvent

Acetone and isopropyl alcohol are generally not suitable for use in extraction, but are frequently used as recrystallization solvents. Explain. After separating layers in an extraction, it is necessary to "dry" the organic layer with a substance that absorbs water. Explain why this is necessary. Suggest two methods for determining which layer in an extraction is the aqueous layer and which layer is the organic layer. An organic compound has a distribution coefficient of 1.5 in methylene chloride and water. If 50 mg of this compound is dissolved in 15 ml. of water, in which case will more of the compound he extracted into the methylene chloride: one extraction with 15 mL of methylene chloride or three extractions using 5 mL of methylene chloride each time? Refer to Appendix B if necessary.

Post-Lab Questions react 1. Draw reaction mechanisms used to for the acid base Nitroaniline. Indicate e on each side of the the reactions if the organie compound would be in the sqeuous or organic layer chemist made some significant modifications; the solvent was changed to dichloromethane (d-1.33g/ml) and th order of collecting HA and 8 is reversed (compared to today's lab). With these changes in mind, prepare/draw a flow chart going from left to right. Indicate which layer is which (organic or aqeuous), fill in reagents (NaOH or HCl) and draw structures in thei proper forms, do not use letter designations here. , 4 chemist designed an acid-base extraction separating the same compounds from today's lab. However, th z A -.ure:オthe pea's of the se resulting in poor recovery ..…aung and purifying a mixture of 3 organic solids by acid base extraction: Benoc Acid(HA -.ouxylic acid, m-Nitroaniline (B) which contains a basic amine group and p-Dichlorobenzene (NJa non-polar compound which doesn't contain any acidic or basic functionality and is considered to be neutral. (HA) c mp, 122.4°C mp. 53.5°C mp. 114c The separation is achieved by first dissolving the mixture in an organic solvent in a separatory funnel. The acidic compound can be extracted by adding a base [NaOMpwhich will ionize the acid, making off and treated with WOPto return the acid to its neutral state, where it will immediately precipitate out of solid can then be collected and dried via vacuum filtration it water soluble. The water layer is then drawn Acidic Compound Baskc Compound cr Add BASE Add ACID Add BASE Soluble in Organie Insoluble in Water Soluble in Water insoluble in Organic Soluble in Orga Inaluble in