Reactions of Atoms and Free Radicals in Solution. Viii. The Reaction of Diacetyl Peroxide With Alkylbenzenes. A New Synthesis of Hexesterol Dimethyl Ether

Kharasch, M. S.; McBay, Henry C.; Urry, W. H.

doi:10.1021/jo01181a004

Cited by 40 publications

(13 citation statements)

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“…The thermal decomposition reactions were carried out behind %-inch Plexiglas screens. The complete apparatus used in these experiments has been described in detail elsewhere (4,13). During the decompositions the analyzed ( 14) peroxide solutions wrere introduced beneath the surface of the heated solvents from dropping-funnels equipped with capillary stems and with water-cooled jackets to prevent the premature thermal decomposition of the peroxides before the solutions reach the vessel.…”

Section: The Steric Factormentioning

confidence: 99%

See 1 more Smart Citation

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

McBay¹,

Tucker²

1954

J. Org. Chem.

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Section: The Steric Factormentioning

confidence: 99%

“…Analysis (14) showed this solution to contain 0.215 mole of peroxide. This peroxide solution was then introduced beneath the surface of 36.0 g. (0.30 mole) of isopropylbenzene heated to 110°, and the decomposition was conducted as described above, see also (4,13), The products isolated from this decomposition are listed in Table I.…”

Section: The Steric Factormentioning

confidence: 99%

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

McBay¹,

Tucker²

1954

J. Org. Chem.

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“…Trinitrotoluene was methylated to give trinitro-m-xylene in 10% yield, using acetyl peroxide as the source of methyl radicals, by Fieser, Clapp and Daudt (1942), although Kharasch, McBay and Urry (1945) were unable to isolate any products of nuclear methylation from the reactions of acetyl peroxide with ethylbenzene or /söpropylbenzene. The only products isolated were the dehydrogeno-dimers resulting from α-hydrogen abstraction and dimerisation of the resulting benzyl-type radicals.…”

Section: Arh + Ch 3 --» Arch 3 + [ H ]mentioning

confidence: 99%

Alkylation

Williams

1960

Homolytic Aromatic Substitution

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“…HOC2H5 + CH3C=0 4 For details concerning the mechanisms of these decompositions see references (1,2,6,7 8). 5 The percentage cleaved is calculated on the basis of the equation given above as follows: 2 X moles of dimer , t u, , TI rvxr , 77577 x 100 = Percentage of the methyl (or ethoxy) moles of methane (or C2HBOH + CH3CHO) free radicals which react by cleavage to give a dimeric product. In some cases methyl (or ethoxy) radicals attack the dimer giving rise to trimers and tetramers.…”

mentioning

confidence: 99%

A COMPARATIVE STUDY OF SOME REACTIONS OF THE METHYL AND THE ETHOXY FREE RADICALS IN A GRADED SERIES OF SOLVENTS¹

McBay¹,

Tucker²,

Milligan³

1954

J. Org. Chem.

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In an earlier paper (1) it has been reported that by a judicious choice of the solvent molecule subjected to attack by a free radical the relative percentages of cleavage2 and of disproportionation experienced by an alkyl free radical or by an alkoxy free radical can be varied. When the solvent molecules in these reactions contained readily cleft hydrogen atoms the cleavage reaction predominated, while a solvent molecule with only difficultly cleft hydrogens caused these free radicals to react to a lesser extent by cleavage and to a greater extent by disproportionation. This evidence supports the theory of the existence of a so-called "energy-factor" (1) in these reactions involving free radicals.The present paper is the preliminary report of a study the purpose of which is to determine the effect that the introduction of the carbomethoxy group3 into a solvent molecule in positions of close proximity to the site of the cleavage attack by a free radical has upon the cleavage tendencies of the methyl and the ethoxy free radical with regard to that solvent molecule. The introduction of this group into said position has little or no effect on the percentage of cleavage exhibited by the methyl free radical, while the proximity of these groups to the preferred seat of attack seems to decrease the percentage of cleavage exhibited by the ethoxy free radical, to increase its percentage disproportionation, and in selected cases, even to reverse the seat of the cleavage attack. It is suggested that these carbomethoxy groups in the solvent molecule exert a possible repulsive effect upon the approaching free radical which repulsion is distinctly greater when this free radical is ethoxy than when it is methyl. This phenomenon involving the contribution of such repulsion to the over-all activation energy required for cleavage by a free radical at a given position in the solvent molecule has been termed the "repulsion factor" (1). In the preceding paper (1) the sol-1 This material has been presented as paper number 84 before the Organic Division of the American Chemical Society a t the Spring meeting, Los Angeles, March 19, 1953. 2 Some referees prefer the term hydrogen abstraction to cleavage. We have for this reason used this term elsewhere (1). Both of these terms apply t o reactions involving the attack of the free radical (here *CHs and *OC&) upon an hydrogen-containing solvent molecule withdrawing therefrom a single hydrogen atom and imprisoning it as part of the resulting molecule (CHa and CZHSOH). This leaves behind a "residual free radical" derived from the solvent molecule. Depending on the nature of this residual free radical, the temperature] the nature of the solvent, and the nature of the parent peroxide molecule, it may react in several ways. In most of the cases here reported the residual free radical dimerizes. In other cases it has apparently disproportionated. J Other groups found t o exhibit a similar effect are chlorine and carboxy. Studies involving these groups will be reported in a later publication. Fl...

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Reactions of Atoms and Free Radicals in Solution. Viii. The Reaction of Diacetyl Peroxide With Alkylbenzenes. A New Synthesis of Hexesterol Dimethyl Ether

Cited by 40 publications

References 3 publications

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

Alkylation

A COMPARATIVE STUDY OF SOME REACTIONS OF THE METHYL AND THE ETHOXY FREE RADICALS IN A GRADED SERIES OF SOLVENTS¹

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Reactions of Atoms and Free Radicals in Solution. Viii. The Reaction of Diacetyl Peroxide With Alkylbenzenes. A New Synthesis of Hexesterol Dimethyl Ether

Cited by 40 publications

References 3 publications

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE1 SOLVENTS

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE1 SOLVENTS

Alkylation

A COMPARATIVE STUDY OF SOME REACTIONS OF THE METHYL AND THE ETHOXY FREE RADICALS IN A GRADED SERIES OF SOLVENTS1

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THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

THERMAL DECOMPOSITION OF DIALKYL PEROXYDICARBONATES IN SOLUTION: REACTIONS OF ALKOXY FREE RADICALS IN PURE¹ SOLVENTS

A COMPARATIVE STUDY OF SOME REACTIONS OF THE METHYL AND THE ETHOXY FREE RADICALS IN A GRADED SERIES OF SOLVENTS¹