Clayden pp. 1200 – 1299

p. 1201 — Don’t understand what happened to the bromine atom in the next to the bottom row of reactions (or if it did happen, how it happened).

p. 1205 — How strong is the N – N bond?

p. 1208 — Would Ethoxide be a strong enough base to deprotonate toluene (e.g. the compound in the second row of reactions without a nitro group?

p. 1212 — You have nitric acid (HN03) as an oxidizing agent, both here and on p. 863, but no clue as to its mechanism of action.

pp. 1217 – 1218 — The problems are getting harder and that’s good. #1 was particularly hard. An amazing series of reactions. How did Botteghi ever think of it?

p. 1219 — “all humans, have their stomach on their left and their liver on the right”. Well, almost all of them do, but there is something called situs inversus in which most body asymmetry is reversed.

p. 1220 — I see why R and L limonene are labeleled the way they are by Cahn Ingold Prelog, but S and R carvone seem incorrectly labeled; C=O should be of high rank than CH=CC.

p. 1220 — Dexfenfluramine (Redux) was also removed from the USA market in ’97 because of side effects. So this part had best be changed in the next edition as it is seriously incorrect. Misprints are one thing, but something totally wrong will start the average reader wondering what else not to believe.

p. 1232 — “Another powerful method of discriminating between enantiomers is to add an enantiomerically pure compound to the sample that does not react with the compound but simply forms a complex with it”. Spoken like a true organic chemist, but not a physical chemist or a biochemist. Complex formation with proteins is the mechanism of action of nearly all the drugs we possess. There’s a huge amount of work to be done here.

p. 1233 “borane is sufficiently reactive to reduce ketones only when complexed with nitrogen atom” — better — “only when borane is complexed with a nitrogen is it reactive enough to reduce a ketone”

p. 1234 — It is isn’t clear (to me) what (if anything) the two phenyl groups are doing in the CBS reagent — they seem to be well out of the action. They might decrease the O – C – C angle in the 5 membered ring.

o, 1235 — Why is trichlorosilane a reducing agent when chloroform CHCl3 is not?

p. 1237 — The diagrams at the top are extremely unclear and should be reworked (perhaps with different colors)
p. 1241– “after treatment with fluoride to remove the silicon” How does this work without wrecking the epoxide??

p. 1249 — “Thiols (RSH) are more acidic than alcohols” — what’s the pKa. Earlier you gave the pKa of ROH at around 15.

p. 1251 — Sidebar. Sulfones are chiral. “Tetrahedral nitrogen atom of an amide” This isn’t true. A larger question is why sufones are chiral and tertiary amines with three different groups attached are NOT chiral. Some explanation should be given in the next edition (assuming one exists).

p. 1252 — “Carbanions next to sulfones are planar, while anions next to sulfoxides and sulfides are ‘believed’ to be pyramidal (sp3 hybridized). Hasn’t anyone been able to look?

p. 1252 — “ab initio calculations suggest that the C-S bond in CH2SH is longer than in CH3SH” — hasn’t anyone measured the bonds?

p. 1254 — “Alkylations of cyclic sulfoxides result in trans stereochrmistry between the new alkyl group and the sulfoxide oxgen atom.” Is this a steric effect of the oxygen atom, or an electronic effect of where the carbanion orbital wants to be?

p. 1256 — There are many more methods for hydrolyzing dithioacetals and their multiplicity should make you suspicious that none is very good.” This is true in spades for any therapy in medicine. Lots of treatments for a disorder mean that none is very good. I once tried over 30 treatments that were all supposed to work for a patient with post-herpetic neuralgia. None did.

p. 1263 — Since sulfur is bigger than carbon the carbon sulfur single bond should be longer making 3 membered sulfur heterocycles more stable than epoxides. So how long is the CS bond? A table of bond lengths and strengths should be in the next edition.

p. 1264 — the C=S bond is described as ‘weak’ and reasons are given, but how weak is it?

p. 1273 — Problem #1 — good to see an extremely hard problem (what happened to the methy group or is this an error?) I didn’t get it. Now to look at the answer after I finish the others. The drawing of the initial structure is incorrect — the methyl group on the oxirane isn’t present in the answer given. I did get to the two 3 membered rings linked together a a quaternary carbon however. It’s a great series of reactions, and the problem should be corrected in the next edition. I feel a lot better now.

p. 1275 — Problem #14 — quite hard — good to see.

p. 1275 — Problem #15 — what does DME stand for ? Not in the index.

The problem set of Chapter 46 was great. Most of the problems were solved by real chemists solving real problems implying that the reader is now up to the sophistication of someone who can read the literature.

p. 1278 — Boron is found in an unusual compound called AI-2. Significantly, it is a quorum sensing molecule — e.g. a way that bacteria ‘talk’ to each other. Since quorum sensing molecules aren’t found in humans, they represent a logical point of attack for drug chemists to develop new antibiotics.

p. 1278 — No explanation of the wierd bonding in B2H6? No one seemed to understand it 50 years ago. Just a bunch of handwaving back then. I hope you explain what’s going on in the next edition.  Surely someone knows by now.

p. 1279 — It seems that you could make more of the fact that the electronegativity of boron (2.04) is less than that of hydrogen (2.20) explaining why BH4- is a good reducing agent. The electronegativity of aluminum is even less (1.61) explaining why AlH4- is a stronger reducing agent that BH4-.

p. 1279 — You actually give the strength of the O – O bond in H2O2 on p. 1051 — why not state this again instead of saying that it very weak ? E. g. 53 kiloCalories/Mole == 222 kiloJoules/mole.   Also to know why carbon migrates to oxygen we should have the strength of the C – B bond (assuming the reaction is thermodynamically driven).

p. 1282 — At the top stereoselectivity is said to be 9:1, but underneath the actual products you have 8 and 1.

p. 1282 — “use the vacant orbital on boron to attack the nucleophile” — a bit strange as you are attacking something (the nucleophile) with nothing (a vacant orbital).

p. 1282 — How do you make O-hydroxylaminosulfonic acid — react ammonia and sulfuric acid?

p. 1287 — The electronegativity of Si is given here as 1.8, but the back of the book has it at 1.9.

p. 1289 — Silyl halides are hard electrophiles — true enough but why are they hard electrophiles? Their electron cloud is more diffuse and larger than that of carbon, so I’d expect the opposite.

p. 1289 — The term triflate is used here before being defined (p. 1321).

p. 1292 — In the discussion of ipso substitution substitution you show the double bond on the left reacting with E+ and then the + charge on the right. Resonance is resonance but this is unnecessarily confusing.

p. 1293 — How do you make R-SiPhMe2 in the first place ? By a Grignard and Cl-SiPhMe2 ??

p. 1297 — “Allyl silanes are more reactive than vinyl silanes as a result of the INCREASED energy of the HOMO due to the interaction of the pi bond with the C-Si bond”. I’d think that this interaction would LOWER the energy of the HOMO.

p. 1299 — What is TMSOTf (TMS is probably trimethyl silicon). It isn’t in the index.
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