The Decomposition of Phenyliodoso Acetate¹

Abstract

Notes 2051 tin in boiling acid solution.1 It was assumed that this coloration was due to the formation of ß-(5pyrrolenyl) -isatin or pyrrole blue B. Recently it has been shown,2 however, that pyrrole blue B in glacial acetic acid has a maximum absorption at 680-690 µ while the maximum absorption in the microreaction was observed in the range for 510-560 m/i. For a more exact comparison the absorption spectrum of the color reaction was determined in a Hilger-Nutting spectrophotometer. The resulting curve A in Fig. 1 is quite different from the spectrum of pyrrole blue B, shown in curve B. The logarithm of specific extinction K is calculated per grams of pyrrole per liter. Thus the compound formed in the color reaction is certainly not pyrrole blue B but seems to be its decomposition product which also forms when solutions of pyrrole blue B are standing for some time. It has been indicated2 that the decomposition product has an absorption maximum at 520 µ.The author is greatly indebted to the Chemistry Department of the University of Michigan for the permission to use a spectrophotometer and to Dr. F. F. Blicke for the supply of pyrrole.

A Catalyst‐Free Minisci‐Type Reaction: the C–H Alkylation of Quinoxalinones with Sodium Alkylsulfinates and Phenyliodine(III) Dicarboxylates

“…[17a], Next, I‐radical B integrates quinoxalin‐2(1 H )‐one ( 1a ) to afford the carbonyl group‐coordinated iodine radical species D , which undergoes a decarboxylation process to form the aminyl radical intermediate E and extrude CO 2 as well as PhI. [7b], [10b], In addition, an alternative route to the intermediate E is also feasible, namely, alkyl radical B′ which is generated form the decomposition of I‐radical B attacks the substrate 1a to furnish intermediate E . Then, intermediate E leads to the target product G through oxidation and deprotonation.…”

Photomediated Controlled Radical Polymerization and Block Copolymerization of Vinylidene Fluoride

“…The vast majority of HVIC applications are oxidations, but as the weak I−O bond of R­(CO)­O−I­(Ph)−O­(CO)­R HVICs is also predisposed to both thermal and photolytic (UV) homolysis, examples of HVIC-based radical processes are beginning to emerge. ,, Aromatic HVICs such as (ArCOO) 2 PhI thermolyze in solution at 125–150 °C via a combination of ionic and radical processes, to form ArCOOPh, ArCOOI, and PhI and ArCOO • , which rapidly decarboxylates to Ar • . − IFAB and DMPI thermolysis data is unavailable, but the thermolysis of IDAB at 127–160 °C , proceeds both heterolytically (∼75%, CH 3 COOPh and CH 3 COOI) and homolytically (∼25%, PhI and CH 3 COO • , i.e., CH 3 • + CO 2 ). The radical pathway is additionally favored by external radical sources, , increasing acetate substitution , and irradiation.…”

“…Interestingly, while the rt thermolysis of IDAB is negligible ( k therm 130°C ≈ 10 –6 s –1 , k therm 40°C ≈ 10 –10 s –1 ), , its rt UV photolysis (Hg-254, 265 nm) proceeds readily ( k UV 28°C ≈ 5.6 × 10 –6 mol L –1 s –1 ) to afford only radical products (CH 3 • ). Similarly, rt UV photolysis of HVICs obtained by ligand exchange of IDAB, , or the more effective IFAB, with RCOOH carboxylic acids selectively affords the corresponding alkyl radicals, as decarboxylation of RCOO • is extremely fast. ,,, Such thermal or photoderived radicals subsequently add to alkenes − or alkylate aromatics. ,− Although no data is available on the visible light photolysis of IDAB, IFAB, and DMPI, it is reasonable to assume that it also proceeds only by homolysis.…”

“…The free radical initiation and propagation is illustrated in panel (a). The rt thermolysis of IDAB is negligible, , and the UV rt photolysis of IDAB and of its congeners derived from IDAB or IFAB ligand exchange with RCOOH readily and selectively generates R • via diffusion-controlled RCOO • decarboxylation. , Therefore, it is reasonable to assume that the low-intensity, visible-light photolysis of IDAB, IFAB, and DMPI, at or around rt, is also homolytic.…”

Radical Substitution In Aromatic Nuclei

“…Alt,ernatively such methylation of polynitro compounds can be effected with acetyl peroxide (136), anode-liberated radicals from the electrolysis of sodium acetate in acetic acid (136), or phenyl iodosoacetate (345). Tetraethyllead and tetramethyllead are ineffective agents (136) for the alkylation of benzene or naphthalene at temperatures up to 300°C.…”