Rate studies and their mechanistic implications for the reaction of 2-methylquinoline 1-oxide and acetic anhydride

Abstract

with the reactivity orders of reagents that react via a cyclic or free-radical mechanism. These observations support the conclusion that iodine isocyanate behaves the double bond. With terminal olefins, dienes, or alkynes, the use of performed solutions of iodine isocyanate is the method of choice.'5 asan electrophilic reagent.The relative reactivities also show that it is advantageous to use the in situ method to prepare iodine isocyanate adducts of internal olefins since the total reaction time (INCO generation plus addition) is less than 3607-48-5; methyl [l-(iodomethyl) heptyllcarbamate, 16666-25-4; 4-iodo-~-a m h h e x a n e hydrochloride, 16666-26-5; 3-iodo-2amino-2,3-dimethylbutane hydrochloride, 16666-27-6. t'hat required to perform iodine isocyanate and add it to (15) B. Grimwood and D. Swern, J . Org. Chem., 82, 3665 (1967).The rate of reaction of 2-methylquinoline I-oxide (1) with acetic anhydride has been measured by three methods which gave similar results. The rate constants are believed to be a product of the equilibrium constant for reaction of 1 with acetic anhydride to form I-acetoxy-2-methylquinolinium acetate (2) and of a rate constant for the latter to yield 2-quinolylmethyl acetate (4). cu,cu,a-Trideuterio-2-methylquinoline I-oxide was found to react one-half rn rapidly as the undeuterated derivative. This, plus the fact the product (4) formed a t about the same rate as the equilibrium mixture of 1 and 2 disappeared, indicates that removal of a methyl hydrogen is the rate-determining step. Also it can be seen that any intermediate between 2 and 4 must have a very fleeting existence.

Deuterium isotope effects and the influence of solvent in the redox and rearrangement reactions of 2-picoline N-oxide and phenylacetic anhydride

“…Analysis by XH NMR spectroscopy indicated a deuterium content of 98% in the methyl group. Phenylacetic anhydride-d4 containing 97% deuterium in the benzyl positions was prepared as described in the Experimental Section. In the first series of reactions the production of benzal- fl Yields were determined by VPC (FID), 6 Results are for duplicate experiments, except for I, which was run in triplicate. Reactions were performed simultaneously.…”

“…d 4 equiv of IV-oxide and 1 equiv of anhydride in 25 ml of benzene heated at reflux under nitrogen for 24 hr. 6 The ratio of each run was determined and the average reported here. dehyde and esters17 was taken as a measure of the relative importance of oxidation and rearrangement pathways, respectively, i.e, k2/kx ^% benzaldehyde/% esters.…”

“…Similarly, a mixture of labeled IV-oxide and labeled anhydride heated in fl Yields were determined by isothermal VPC (TC). 6 Results are for duplicate experiments. 6 Reactions correspond to those in Table I.…”

“…It should be noted that in this system the determination of hydrogen isotope effects by the method of competition has an inherent advantage over a direct measurement of ka and kn-Variations in product ratios reflect simply the relative rates of decomposition of acylated N-oxide 1 (R = Me), whereas ka (or kr,) would contain a contribution from a pre-rate-determining equilibrium (acylation) step. 6 The latter could conceivably be subject to a secondary isotope effect when phenylacetic anhydride-c¿4 is allowed to react. Determination of hydrogen isotope effects by competition avoids the necessity for knowing the uncertain magnitude of that effect.…”

Aromatic N-oxides. VII. Reaction of diphenyl-2-pyridylmethane N-oxide with acetic anhydride

“…Received September 18,1974 Acetylenedicarbonyl fluoride (3) has been prepared by (a) reaction of SF4 with the monopotassium salt of acetylenedicarboxylic acid and (b) by reaction of phenylsulfur trifluoride with acetylenedicarboxylic acid. The physical and spectral properties including a mass spectral analysis of 3 have been determined.…”