04-BS-12 · Undated paper
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exam 04-BS-12, Organic Chemistry — May 2019 sitting (the page-1 header and the running footer, "04-BS-12/May 2019", both give the date). 3 hours, closed-book examination; one Casio/Sharp-approved calculator 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. (acid/base theory, functional-group identification, SN1/SN2 mechanisms and stereochemistry, alkyne/acetylide synthesis, electrophilic aromatic substitution, IR/NMR/mass-spectral structure elucidation, named-drug synthesis design, and step-growth polymer chemistry). Every molecular formula, exact mass, and stereochemical (R/S, cis/trans) 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.
The difference is one of polarity and fat solubility, not of dose or potency. THC (tetrahydrocannabinol) is an almost entirely hydrocarbon molecule — a large fused-ring system bearing only one phenolic O–H and one ether oxygen among some twenty carbons — so it is highly lipophilic (log P ≈ 6–7). It partitions out of the blood and into adipose (fatty) tissue, where it is stored with a very long tissue half-life; it is then released back into the bloodstream slowly over days to weeks and its metabolites (11-nor-9-carboxy-THC) remain detectable in urine long after the drug's psychoactive effects have ended. Ethanol, by contrast, is a small, fully water-miscible molecule (log P ≈ −0.3) with no significant fat depot to accumulate in. It is metabolised rapidly and completely by alcohol dehydrogenase and aldehyde dehydrogenase (zero-order kinetics at typical doses, roughly one standard drink per hour) and is essentially fully cleared from the body within a day, leaving no persisting parent compound or long-lived metabolite for a screen to find weeks later.
