Category Archives: Fall 2012 Organic Chemistry Lab

A Dibromination Dibromance Part IV

We divided the procedure into three different studies. One study involved the “traditional” use of 1 mL of concentrated HBr and H2O2. The second study mixed 0.5 mL of HBr and 0.5 mL of HCl, and the third study used 1 mL of HCl. The products were recovered by neutralizing the reaction mixture and collecting […]

A Dibromination Dibromance Part III

The protocols for the in situ formation of bromine from hydrobromic acid and hydrogen peroxide and subsequent reaction with an alkene vary somewhat in the literature. If the alkene can be dissolved in a water-miscible solvent such as ethanol, then the reaction can be done without a phase transfer compound. For example, trans-stilbene is dissolved […]

A Dibromination Dibromance Part II

Another interesting aspect to the dibromination reaction is that three different methods have been developed to perform the same reaction in the undergraduate laboratory. Of course, many more methods of dibromination exist in the chemical literature. Some laboratory manuals, such a Nimitz, still propose the dibromination reaction using diatomic bromine in a halogenated solvent such […]

A Dibromination Dibromance Part I

This year we performed a dihalogenation reaction that is featured in the reactions of alkenes: a topic  typically covered during first semester Organic Chemistry. This reaction has been a popular undergraduate experiment for decades. I did quite a bit of background research in setting this one up. The two most popular substrates are trans-cinnamic acid […]

Watered Down Dehydration

We are continuing our investigation of the acid catalyzed dehydration of 2-methyl-1-cyclohexanol. This year we compared diluted phosphoric acid to the concentrated phosphoric acid (48% w/w aqueous solution) that we have been routinely using. The procedure calls for 11.5 grams of alcohol and 2.5 mL of concentration H3PO4 which may be a large excess of […]

E2 Brutus? Part IV

We did not remove the solvent because the amount of liquid product would have been too small to do analyses like RI and IR. Instead, the students performed a Br2 qualitative test with the upper (organic) phase. This was a little problematic as well. The students were instructed to count how many drops it took […]

E2 Brutus? Part III

The manner of heating and stirring the reaction was also an issue I considered. I decided to use boiling stones rather than stirbars. Stirbars are expensive and students tend to dump them down the drain or wash them into the waste bucket. I went with using the thermwells rather than the boiling water bath. We […]

E2 Brutus? Part II

Scale: The original lab is written for microscale using 0.22 mL of 2-bromoheptane with an overall reaction volume of 2.22 mL. The 2-bromoheptane is a pretty expensive reagent and ended up being the limiting factor in how much the reaction could be scaled up. The smaller the reaction volume, the greater skill is required of […]

E2 Brutus? Part I

This is an experiment that I performed as part of a Chemistry Collaborations Workshops & Community of Scholars (cCWCS) workshop during the summer of 2011. I had planned on incorporating the experiment the next time I taught Organic Chemistry I. Since substitution and elimination is a topic in first semester organic chemistry (Chapter 6 in […]