Convenient Preparation of 2,7,8‐Trimethyl‐6‐hydroxychroman‐2‐carboxylic Acid (γ‐Trolox)

The title chroman is useful in synthesis and as a water‐soluble analog of γ‐tocopherol, a member of the vitamin E family. This new synthesis of γ‐trolox proceeds via selective aromatic demethylation of Trolox, the more easily available 2,5,7,8‐tetramethyl homolog compound. This route is shorter than the previous synthesis, avoids the use of cyanide and methoxybutadiene, and requires no chromatography.     

Reaction probabilities and high energy trajectories for collinear H−H2 collisions

Classical trajectory studies of the collinear H + H₂ system, under the influence of a Sato potential, have been used to obtain reaction probabilities over a wide range of collision energies. Although the low energy trajectories are simple, some high energy trajectories are complicated and lead to the reactants being in close proximity for long enough to be considered a complex. The excess energy may be liberated in vibrational or translational form.     

A new synthesis of 3-amino-1-aryl-2-pyrazolin-5-ones

Reaction of ethyl 3-nitropropionate with aryldiazonium chlorides in basic medium yields ethyl 3-nitro-3-(arylhydrazono)propionates. These α-nitrohydrazones are converted by catalytic hydrogenation to 3-amino-1-aryl-2-pyrazolin-5-ones, probably via cyclization of intermediate amidrazones produced in situ. This appears to be the first route to the title compounds that does not use a substituted phenyl hydrazine intermediate and offers advantages in the preparation of pyrazolinones bearing electron-rich aryl rings.