Question

2. Was benzene present as a side product in the GC? If so, try to identify it (there is likely no standard for comparison in our lab facility because of benzene's toxicity). 3. What steps were taken to keep the system water free? Name each precaution taken. 139

Answer 1

2) GC is not given here and hence may not be possible to answer this question. In GC try to locate the small peak having a small retention time. This small peak may be is of the benzene. 3) Drying is very essential in case of Grignard reaction. Even traces of water may fail the experiment. I am not sure what steps you followed in the experiment, however in general these are the precautions we take while performing this experiment: 1) All apperatus should be dried before use. 2) All the solvents used should be distilled and dried and stored in dry condition. 3) Acetone used in this experiment should be distilled and dryed over molecular seves. 4) Mechanism: CH3 CH L. Học | Н4С OH MgBr CH3 Hacov 2-phenylpropan-2-01 Grignard reagent makes the polarity reversed in brom obenzene. The carbon becomes and nucleophile and attacks on electrophilic carbonyl carbon. 5) Your IR should contain: 3300: broad peak -OH stretching 3026: sp2 C-H stretching 2976 and 2872: sp3 C-H stretching

1609: Aromatic C=C stretching 1495: CH3 rocking 1373: C-H bending 1267: C-O stretching The reference IR is available in "2-phenyl-2-propanol" chemicalbook. open source: search for the 6) THF is more basic in nature than the DEE and it forms more stronger complex with Mg2+ to stabilize the Grignard reagent. 7) Alternative synthesis: 0 H.C. 93 CH3COcio CH3MgBr CH. THE Y OH AICI3 step-1: Fridel-Craft acylation and then reaction with Grignard reagent methylmagnesium bromide to give desired alcohol. 8) The alcoxide anion need to be protonated and hence we add HCl to make the pH low so that protonation is ensured. 9) It may not be possible to answer as procedure is not given here. 10) NMR:

(C2H HA? CH, CE B ¢MOHDi c ppm 7.44 7.36 7.25 2.05 1.552 (BHG KMU A CH,(E) ICH НКА) 11) Litrature boiling point is 202°C 12) If IR, NMR and boiling point matches then the reaction is succesful.