D. Schroder et al., GENERATION OF ALPHA-ACETOLACTONE AND THE ACETOXYL DIRADICAL CENTER-DOT-CH2COO-CENTER-DOT IN THE GAS-PHASE, International journal of mass spectrometry and ion processes, 165, 1997, pp. 71-82
Citations number
62
Categorie Soggetti
Spectroscopy,"Physics, Atomic, Molecular & Chemical
The formation of neutral [C-2,H-2,O-2] has been investigated by tandem
mass spectrometry in a sector instrument and by energy-resolved colli
sion-induced dissociation in a flowing afterglow-triple quadrupole app
aratus. The neutral species are generated by two different methods: (i
) neutralization of the distonic anion radical (CH2COO-)-C-. by collis
ional electron detachment and (ii) collision-induced loss of halides X
-concomitant with formation of [C-2,H-2,O-2] from alpha-haloacetate io
ns XCH2COO-. The tandem mass spectrometry results suggest that neutral
ization of (CH2COO-)-C-. and high-energy collisional activation of alp
ha-haloacetate ions lead to a mixture of alpha-acetolactone, c-(CH2C(O
)O), and the acetoxyl diradical, (CH2COO.)-C-.. Low-energy collisions
with alpha-chloroacetate ions in the triple quadrupole analyzer produc
e alpha-acetolactone exclusively at the dissociation threshold. From t
he dissociation threshold measured for the appearance of Cl- from ClCH
2COO- the heat of formation of acetolactone is determined to be Delta
H-f,H-298 = -47.3 +/- 4.7 kcal/mol. (C) 1997 Elsevier Science B.V.