ChemInform Abstract: SELECTIVE BROMINATION OF HALOBENZENES USING ZEOLITE CATALYSTS

Wortel, Th. M.; Oudijn, D.; VLEUGEL, C. J.; Roelofsen, D. P.; Bekkum, H. van

doi:10.1002/chin.198004162

Cited by 7 publications

(12 citation statements)

References 1 publication

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“…6 We have extensively reported that dimethyl carbonate (DMC) behaves as a very selective mono-C-methylating agent for a variety of active-methylene compounds [eqn. (2)].…”

Section: 4mentioning

confidence: 99%

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Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites

Selva¹,

Bomben²,

Tundo³

1997

J. Chem. Soc., Perkin Trans. 1

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The reaction of dimethyl carbonate (DMC) with different primary aromatic amines has been investigated under batch conditions (autoclave) in the presence of Y-and X-type zeolites. Operating at 120-150 ЊC, highly selective mono-N-methylations are observed for anilines even when they are deactivated by either electronic effects or steric hindrance (G᎐C 6 H 4 NH 2 , G = p-NO 2 , p-CN, o-CO 2 CH 3 and 2,6-dimethylaniline); typical selectivities for the formation of the corresponding mono-N-methyl derivatives [ArNH(CH 3 )] are in the range 92-98%, at a substrate conversion of 72-93%. A synergic effect between the reactivity of DMC (acting both as a methylating and as a reversible methoxycarbonylating agent) and the dual acidbase properties of zeolites is considered to be responsible for the unusually high selectivity observed; accordingly, a reaction mechanism is discussed, involving carbamates (ArNHCO 2 CH 3 ) and N-methylcarbamates [ArN(CH 3 )CO 2 CH 3 ] as intermediates. The reaction is an example of a synthesis with low environmental impact: it couples the use of a non-toxic methylating agent (DMC, in place of the highly toxic methyl halides or dimethyl sulfate) with eco-friendly catalysts (zeolites) in a waste-free process.

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“…6 We have extensively reported that dimethyl carbonate (DMC) behaves as a very selective mono-C-methylating agent for a variety of active-methylene compounds [eqn. (2)].…”

Section: 4mentioning

confidence: 99%

“…(6)] and, due to its polarity, it can be retained there and forced to undergo both methylation and demethoxycarbonylation reactions before it exits [eqns. (8) and (10)].…”

Section: 14mentioning

confidence: 99%

Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites

Selva¹,

Bomben²,

Tundo³

1997

J. Chem. Soc., Perkin Trans. 1

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“…In the many prior studies of zeolite-induced aromatic bromination reactions [160,[169][170][171][172] selectivities at total conversion were significantly less, especially for toluene. Also, conventional wisdom would maintain that space within the pores of zeolite Y was so abundant that there was little opportunity for significant shape-selectivity.…”

Section: Selective Bromination Of Aromatic Compoundsmentioning

confidence: 95%

“…There have been a number of studies of solid catalysts in regioselective bromination of aromatic compounds [160][161][162][163][164][165][166]. However, in many cases limited improvement in selectivity was shown.…”

Section: Selective Bromination Of Aromatic Compoundsmentioning

confidence: 99%

Regioselective Electrophilic Aromatic Substitution Reactions over Reusable Zeolites

Smith¹,

El‐Hiti²

2006

COC

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“…However, preparation of mono-N-methylanilines (II) in this way is severely restricted due to the low steric hindrance of the methyl group and sizable amount of N,N-dimethyl derivatives are always observed, when methyl halide or dimethyl sulphate is used as the alkylating agent. Moreover, when alkyl halides are used, an additional problem is encountered, wherein the co-product HX rapidly deactivates the zeolites [7].…”

Section: Introductionmentioning

confidence: 99%

Zeolite-promoted selective mono-N-methylation of aniline with dimethyl carbonate

Esakkidurai

Pitchumani

2004

Journal of Molecular Catalysis A: Chemical

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ChemInform Abstract: SELECTIVE BROMINATION OF HALOBENZENES USING ZEOLITE CATALYSTS

Cited by 7 publications

References 1 publication

Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites

Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites

Regioselective Electrophilic Aromatic Substitution Reactions over Reusable Zeolites

Zeolite-promoted selective mono-N-methylation of aniline with dimethyl carbonate

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