57573-52-1Relevant articles and documents
Formation and decomposition of diazo ethers under acidic conditions. Effects of ethanol concentration, acidity, and temperature on the ethanolysis of 4-methylbenzenediazonium ions
Fernandez-Alonso, Alejandra,Bravo-Diaz, Carlos
scheme or table, p. 877 - 887 (2010/08/06)
We investigated the effects of solvent composition, acidity, and temperature on the dediazoniation of 4-methylbenzenediazonium (4MBD) ions in EtOH/H2O mixtures by employing a combination of spectrometric and chromatographic techniques. First-order behavior is found in all solvent composition ranges. HPLC Analyses of the reaction mixtures indicate that three main dediazoniation products are formed depending on the particular experimental conditions. These are 4-cresol (ArOH), 4-phenetole (ArOEt), and toluene (ArH). At acidities (defined as -log [HCl])a turnover in the reaction mechanism takes place under acidic conditions. At any given EtOH content, the plot of kobs values against acidity is S-shaped, the inflexion point depending upon the EtOH concentration and the temperature. Similar S-shaped variations are found when plotting the dediazoniation - product distribution against the acidity. The acid dependence of the switch between the homolytic and heterolytic mechanisms suggests that the homolytic dediazoniation proceeds via transient diazo ethers, and this complex kinetic behavior can be rationalized by assuming two competitive mechanisms: i) the spontaneous heterolytic dediazoniation of 4MBD, and ii) an O-coupling mechanism in which the EtOH molecules capture ArN 2+ to yield a highly unstable (Z)-adduct which undergoes homolytic fragmentation initiating a radical process (Scheme). Analyses of the effects of temperature on the equilibrium constant for the formation of the diazo ether and on the rate of splitting of the diazo ether allowed the estimation of relevant thermodynamic parameters for the formation of diazo ethers derived from methylbenzenediazonium ions under acidic conditions.
Preparation of Fluoroarenes in One-Pot Diazotization and Fluoro-Dediazoniation of Aminoarenes Using HF or HF-Base. The Functions of Bases in the HF Solution
Fukuhara, Tsuyoshi,Sasaki, Satoshi,Yoneda, Norihiko,Suzuki, Akira
, p. 2058 - 2062 (2007/10/02)
In a one-pot diazotization of anilines followed by fluoro-dediazoniation in situ using HF or HF with bases (HF-Base) as a solvent, the diazotization stage has been found to play the most important part to yield fluoroarenes effectively.Diazotization of anilines was greatly influenced by the composition of the HF solution, and greatly enhanced by employing appropriate amounts of bases, such as pyridine.On the other hand, fluoro-dediazoniation of diazonium salts, once formed, took place very readily in HF or HF-Base to produce fluoroarenes in high yield, although such bases served to slow down the rate of decomposition of diazonium salts to some extent.
Rate Data for Oxidation of p-Methylphenylhydrazine with Thallium(III) in Acid Chloride Solutions
Banthiya, U. S.,Joshi, B. C.,Gupta, Y. K.
, p. 329 - 330 (2007/10/02)
The oxidation of p-methylphenylhydrazine (PMP) with Tl(III) in acid chloride solutions shows a first order dependence each on , and and an inverse dependence on and .Its reactivity is guided by the complex formation between Tl(III) and PMP.
