04-BS-12 · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exam 04-BS-12, Organic Chemistry — December 2019. 3 hours, closed-book examination (no calculator; one hand-written aid sheet permitted); NOTES on page 1 state that TEN (10) questions constitute a complete exam paper and only the first 10 as they appear in the answer book are marked, but this sitting prints 13 numbered questions — every question and sub-part below is answered in full.
Reference texts: McMurry, Organic Chemistry, 9th ed. (functional groups, stereochemistry, SN1/SN2 mechanisms and stereochemistry, steroid/bile-acid amphiphilicity, named-drug synthesis design, reaction-energy diagrams, polymer chemistry, arene-oxide metabolism, and mass-spectral/IR/NMR structure elucidation). Every molecular formula, exact mass, and stereochemical (R/S, cis/trans, meso/chiral) assignment below.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Every polymer here is a simple radical addition polymer, so each repeat unit's monomer is found by "un-joining" the backbone at the two single bonds flanking each repeat unit and re-forming the alkene double bond.
a) Teflon is –[CF2–CF2]n–: the monomer is tetrafluoroethylene, CF2=CF2.
b) Poly(ethyl acrylate) is –[CH2–CH(COOEt)]n–: the monomer is ethyl acrylate (ethyl prop-2-enoate), CH2=CH–COOCH2CH3.
Poly(methyl methacrylate). Radical polymerisation opens the CH2=C(CH3)COOCH3 double bond and links the monomers head-to-tail through the former alkene carbons:
