CHEM 341 Problem Set 20 Halloween Edition When confronted with a vampire (I mean a real one, not one of the Twilight wannabes), the first thing that kicks in is inevitably the flight or fight response. This is brought to you by adrenaline. The molecule below is adrenaline. It actually exists as the R enantiomer. Redraw it as the R enantiomer. 1 OH OH H N H 3 N 2 HO HO OH OH So, you've decided to fight the vampire. Bad decision, but oh well, you should not have invited him inside in the first place. Your best hope, is to fight with light, but with power out (I know it is cliche), you have to generate light somehow. Light sticks work by the slow reaction of hydrogen peroxide with diphenyloxalate to generate a four member ring. The four member ring (dioxetane) decomposes in a single step (2 arrow mechanism) to form carbon dioxide. One of the carbon dioxide molecules is especially excited and when it hits a dye molecule, the dye molecule gives off light. Hydrogen peroxide is nucleophilic enough to attack the unactivated carbonyl of a phenyl ester by itself. Draw the mechanism for the transformation of the diphenyl oxalate with hydrogen peroxide. O O O O OH H O O O 2 O O O H (diphenyl oxalate) (hydrogen peroxide) (dioxetane) (phenol) Draw in the arrows for the decomposition of the dioxetane to give carbon dioxide. One problem, the light isn't bright enough to scare away the vampire. You need it be brighter. Well, sodium hydroxide to your rescue. Hydrogen peroxide has a pKa about 11. If you want the light stick reaction to glow brighter, you can add a catalytic amount of sodium hydroxide. Why would this make the reaction proceed faster and subsequently brighter? (BEWARE: if you make the reaction brighter, the light does not last as long). Hydroxide can deprotonate the hydrogen peroxide making it into a better nucleophile. Having a better nucleophile will speed up the reaction. Turns out the light stick reaction was not bright enough, and well now you are dead or more precisely undead. Even though old age is no longer an issue, you still got quite a few things to worry about. Now, that you are a vampire, you still have to find food. Luckily, people aka (happy meals with legs1) are still quite abundant. Problem is all of them are too smart to invite a vampire in. And vampires are easy to spot. Pale skin? Pointy teeth? Vampire. The teeth you can hide, but the pale skin? You can't exactly get a tan because the whole aversion to sunlight and tanning beds are quite possibly carcinogenic. But, organic chemistry comes to the rescue with spray tans! Erythrulose reacts with the amines found on skin proteins to create red-bronze compounds. 1 That is a reference from Buffy the Vampire Slayer The first step of this process is the formation of imines and enamines. Draw the mechanism for the formation of the imine. R R O OH catalytic N OH HN OH acid NH2 HO HO R HO OH OH OH erythulose Imine Enamine Unfortunately, you went with the cheap spray tans that contain a lot of dihydroxyacetone. Now instead of looking like you were spending the day at the beach, you look like an Oompa Loompa, but at least you don't look like a vampire. Dinner time! Vampires have the worse luck when it comes to oral hygiene. They not only have to worry about gingivitis and plaque, but also unsightly blood stains. Thankfully, Professor Karl Link at the University of Wisconsin came to the rescue in 1938 with his isolation of warfarin, a common blood thinning agent. After brushing their teeth, vampires apply to the anticoagulant to their pearly whites to stop blood from clotting on them. But, it is important that they brush first and apply the warfarin second as the toothpaste is typically basic due to the fluoride and bicarbonate anions. These anions are capable of deprotonating the warfarin and the resulting warfarin anion is washed away. Draw the deprotonated form of warfarin and its resonance structures labeling major and minor. O OH O O Warfarin O O O O O O O O major minor O O O O major When Zombies attack: What would a good Halloween problem set be without the incorporation of zombies? The molecule on the next page is tetrodotoxin. This molecule is the "active ingredient" in poisonous puffer fish and urban legend would have us believe is the principle ingredient to make zombies using Voodoo. What is the molecular formula for tetrodotoxin? Label the stereocenters indicated with an * as R or S. O OH O C H N O O NH2 11 17 3 7 S * N H HO * * N R R HO H OH Tetrodotoxin Is there an antidote for zombieism besides a baseball bat to the head? I don't know, but it might be worth a shot to cook the zombie in a vat of sulfuric acid and water at a high temperature. That could possibly convert tetrodotoxin to one of these compounds (that may or may not cause the undeparted to well depart). Draw the mechanism of the following reactions. O O O OH HO O OH OH HO O NH2 H SO OH OH 2 4 OH NH2 H2SO4 N OH N H H2O CO 2 NH4 HO N H H O NH 2 HO N 2 3 HO H HO H HO OH OH O OH Finding a cure to being cooked in sulfuric acid in water would be a significantly harder challenge. Now, zombies may or may not exist, but zombie ants do! Google it. It is pretty creepy and cool. It turns out there is a fungus that turns ants into mindless zombies. Maybe an antifungal medication would cure those ants. Clotrimazole (the active ingredient is the antifungal Lotrimin) might work. Say McGuyver is trapped in a chemistry laboratory by giant mutant zombie ants and does not have a paper clip, Swiss army knife, or his athlete's foot medication handy, he may still be able to last another season. He can heat imidazole and 2- chlorotrityl chloride in the presence of triethylamine to make Clotrimazole and save the day. Draw the mechanism of the reaction below. Which N is the nucleophilic N? The following pKas may help you decide on the proper mechanism. pKa of conj. acid of imidazole ~ 7 pKa of conj. acid of triethylamine ~ 10 pKa of imidazole ~ 14.5 N H N Cl N Et3N N imidazole Cl Cl clotrimazole 2-chlorotritylchloride (And if the clotrimazole does not work, there is always that vat of sulfuric acid and water). Wikipedia was very helpful in the writing of this problem set. .