140226-34-2

Upstream product

• 87059-79-8 2-hydroxy-α-(hydroxymethylene)acetophenone 
• 1402242-73-2 potassium trifluoro(3-(2-methoxyphenyl)-1-methyl-1H-pyrazol-5-yl)borate 
• 1776-12-1 1-(2-methoxyphenyl)prop-2-yn-1-ol 
• 1402242-64-1 potassium trifluoro(3-(2-methoxyphenyl)-3-oxoprop-1-ynyl)borate 
• 1402242-58-3 potassium trifluoro(3-hydroxy-3-(2-methoxyphenyl)prop-1-yn-1-yl)borate 
• 123532-18-3 3-(2-hydroxyphenyl)-1-methyl-1H-pyrazole 
• 74-88-4 methyl iodide 

Relevant academic research and scientific papers

Synthesis of ynone trifluoroborates toward functionalized pyrazoles

The synthesis of a range of novel ynone trifluoroborates has been achieved, in a two-pot process from propargylic alcohols. These alkynes have been subsequently used in the formation of a range of pyrazole trifluoroborate salts via cyclization with hydrazines. The products are generated with high levels of regiocontrol and in excellent yields and represent versatile synthetic intermediates.

New ultraviolet stabilizers: 3- and 5-(2′-hydroxyphenyl)pyrazoles

A new class of ultraviolet stabilizers, the C-(2?-hydroxyphenyl)pyrazoles, is described. The combined use of X-ray crystallography [3(5)-(2′-hydroxyphenyl)pyrazole (5), l-methyl-3-(2′-hydroxyphenyl)pyrazole (7), and 1-methyl-5-(2?-hydroxyphenyl)pyrazole (8)], NMR (1 and 13C), and UV spectroscopies allows the determination of the major tautomers, the coplanarity of both rings if present, and the existence of hydrogen bonds. Compounds 5 and 7, in which there is an intramolecular hydrogen bond (IMHB), do not fluoresce in cyclohexane. Solvent and temperature experiments prove that for these compounds in cyclohexane proton transfer took place in the excited singlet state but not in the triplet state (phosphorescence) and that the latter one is of higher energy than the former. The fact that the absorptions of planar 1-methyl-3-(2′-methoxyphenyl)pyrazole (9) and nonplanar 1-methyl-5-(2′-methoxyphenyl)pyrazole (10) are quite different whereas their emissions are very similar suggests that 10 might behave as a laser dye in the UV region (from an excited planar form to a ground state nonplanar form). Finally, the photostability of (2'-hydroxyphenyl)- and (2′-methoxyphenyl)pyrazoles was determined, compound 7 being even more stable than Tinuvin P.