Dimethylthiocarbamoyl Chloride

Ponaras, Anthony A.; Zaim, Ömer

doi:10.1002/047084289x.rd390

Cited by 2 publications

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References 48 publications

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“…The thermally induced rearrangement of O -arylthiocarbamates ( 1 ) was discovered in the 1960s and is commonly referred to as the Newman−Kwart rearrangement (NKR). The ready preparation of N , N -dimethyl O -arylthiocarbamates from the corresponding phenol, and the facile cleavage of the S -arylthiocarbamate rearrangement products ( 2 ), has resulted in the NKR becoming one of the prime routes to thiophenols, Scheme , with applications as diverse as chiral ligands, agrochemicals, dyestuffs, pharmaceutical intermediates, copper−protein mimics, and precursors to supramolecular assemblies …”

Section: Introductionmentioning

confidence: 99%

The Molecularity of the Newman−Kwart Rearrangement

et al. 2010

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It was recently reported that the venerable Newman-Kwart rearrangement (1→2) proceeds via mixed first- and second-order kinetics. Prior to this, the rearrangement had been considered to proceed exclusively via an intramolecular O(Ar)→S(Ar) migration. A new bimolecular pathway, possibly involving an 8-membered cyclic transition state, was proposed to account for reaction rates that increased disproportionately with substrate concentration under microwave heating conditions. We report a reanalysis of the kinetics and molecularity of the rearrangement of N,N-dimethyl O-(p-nitrophenyl)thiocarbamate 1a in N,N-dimethylacetamide solvent. Using HPLC, isotopic labeling ((2)H, (18)O, (34)S), and ESI-ICRMS methods, we show that there is no evidence for a bimolecular pathway en route to 2a, with near-perfect exponential decay in 1a at concentrations ranging from 0.11 to 4.70 M. Instead, it is demonstrated that under the microwave heating conditions, a delayed negative feedback signal to the microwave power balancing loop results in oscillatory reaction overheating. Due to higher tan δ in the solute, the amplitude of this oscillation increases with the concentration of 1a, and this phenomenon best accounts for the kinetic behavior previously misinterpreted as being mixed first- and second-order in nature.

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Section: Introductionmentioning

confidence: 99%

The Molecularity of the Newman−Kwart Rearrangement

et al. 2010

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“…The 3-phenylglycidol , 1 (Scheme ) was treated first with sodium hydride in THF in the presence of a catalytic amount of imidazole and then with the dimethylthiocarbamoyl chloride , [ClC(S)NMe 2 ] in an attempt to prepare thiocarbamate 2 . The product, isolated in 67% yield, showed the expected elemental composition (HRMS).…”

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confidence: 99%