Exam > Columbia University CHEM UN2045 Organic Chemistry I CHEM UN2045 Exam 2

Document Content and Description Below

1. Consider the alkene isomers below, each labeled with a letter of the alphabet. Each one of the alkenes above was subjected to two separate chemical transformations, ozonolysis and bromination. In... terestingly, only the three alkenes in boxes i, ii, and iii gave one unique product after ozonolysis (the alkenes in box ii and iii yielded the same product). Out of those three alkenes, the alkene in box i gave an achiral, non-meso compound after bromination, box ii gave a racemic mixture, and the alkene in box iii gave a meso compound. The remaining two alkenes in box iv and v gave two products after ozonolysis, but after bromination, the alkene in box iv yielded an achiral, non-meso compound; and the other alkene in box v produced diastereomers. 1a. 18 pts. Identify the alkenes in the appropriate boxes below, corresponding to the label above; and draw the chemical structure of the resulting product(s) in the empty boxes below. 1b. 6 pts. Another experiment with all of the alkene isomers showed that in a reaction with DBr, three alkylhalides were formed as a result of a rearrangement (1,2-shift by hydrogen, methyl, or alkyl groups). Draw the structures of the resulting alkyl halides below (no need for dashes/wedges in this answer). A B C D E F G H I J L M N O P R K Q Alkene isomers: C6H12 one product 1) O3 2) Me2S one product 1) O3 2) Me2S 1) O3 2) Me2S 1) O3 2) Me2S 1) O3 2) Me2S two products two products achiral, non-meso compound a meso compound racemic mixture achiral, non-meso compound diastereomers (draw one) ALKENES: (insert alphabetical label) Br2/ DCM Br2/ DCM Br2/ DCM Br2/ DCM Br2/ DCM box i box ii box iii box iv box v This study source was downloaded by 100000859607764 from CourseHero.com on 01-02-2023 10:36:47 GMT -06:00 https://www.coursehero.com/file/28301942/Exam-2pdf/Name: 3 pts. this pg. 2. There are various alkene constitutional isomers of the molecular formula C5H8 (two degrees of unsaturation). A few of those isomers (compounds A-F) were reacted under vigorous oxidation (with H3O+ and KMnO4) to yield specific products. Please provide the correct structure of the reactants and products in the corresponding boxes that fit the appropriate description. Draw dashes and wedges, where necessary, to show stereogenic centers. Note: you can assume that CO2 will bubble away whenever it is generated. So, if a reaction yields one product and CO2, it is okay to assume that the product is pure because CO2 will bubble away. 2a. 8 pts. Compounds A and B are diasteromers that yield the same products upon vigorous oxidation. 2b. 4 pts. Compound C loses 2 eq. of CO2 that bubble out of the reaction mixture to yield a single symmetric product (i.e. it contains a plane of symmetry). 2c. 8 pts. D and E are cyclic compounds that form products X and Y, plus CO2. Both X and Y are constitutional isomers of each other (molecular formula C4H6O). Compound D is a racemic mixture (a pair of two enantiomers), and so is its product X. Just draw one enantiomer, or simply draw only one line-structure that represents the racemic mixture. or KMnO4 H3O+ A B KMnO4 H3O+ C + 2 CO2 continued (next page) KMnO4 H3O+ D (racemic) + CO2 KMnO4 H3O+ E + CO2 X (C4H6O, racemic) Y (C4H6O) 4 pts. this pg. 2d. 4 pts. Compound F yields a single di-ketone product (no formation of CO2, no carboxylic acids). 3. 12 pts. Fill in the chemical structure in the empty boxes below. Compounds A, B, and D are isomers with a molecular formula of C9H16. Note: There is no need to draw dashes and wedges where chiral centers are formed. KMnO4 H3O+ F A 1. OsO4 [Show More]

Last updated: 1 year ago

Preview 1 out of 7 pages