A particularly good reagent for allylic bromination is N-bromosuccinimide (NBS). The mechanism. The bromine reacts with the alkene by radical chain mechanism. The bromination reactions and mechanisms are compared. In fact, this reaction starts out just like the alkene halogenation mechanism. Allylic Bromination Explained: Under radical conditions, alkanes containing allylic hydrogens enter into allylic halogenation. name: danielle curtis partners: gabbi nguyen misturah abdulkareem ta: olapeju oyesiku 4/6/2017 experiment 10: greener bromination of stilbene and qualitative. The second Br breaks away as a negative bromide in solution. During a chain reaction, for every reactive species you start off with, a new one is generated at the end - and this keeps the process going.The over-all process is known as free radical substitution, or as a free radical chain reaction. Organic Chemistry Laboratory I (CHM2210L) Academic year . The attacked bromine atom retaliates and attacks the carbon with one of its lone electron pairs. Course. Sign in Register; Hide. The nucleophilic pi electrons attack a neutral bromine molecule. You will probably find that your examiners will accept this one, but you must find out to be sure. Reaction of an alkene with aqueous potassium permanganate results in addition of two hydroxyl groups to each side of the double bond to form a glycol. 2016/2017. University. We describe two new greener alkene bromination reactions that offer enhanced laboratory safety and convey important green chemistry concepts, in addition to illustrating the chemistry of alkenes. The resulting product is a vicinal (neighboring) dihalide. University of South Florida. You need to refer to recent mark schemes, or to any support material that your examiners provide. Helpful? Organic Chemistry Lab Report #10. You almost certainly won't be able to tell this from your syllabus. Reaction Overview: The alkene halogenation reaction, specifically bromination or chlorination, is one in which a dihalide such as Cl2 or Br2 is added to a molecule after breaking the carbon to carbon double bond. I earned an A in this lab class. The mechanism involves a chain reaction. 19 4. The halides add to neighboring carbons from opposite faces of the molecule. To Conduct Demonstration: Pour two samples of heptane and two samples of cyclohexene into separate test tubes in a lighted rack. One version is simplified to bring it into line with the other alkene electrophilic addition mechanisms.