acetyl group (–COCH 3 ) from a mol-
ecule. Deacetylation is an important
reaction in several biochemical path-
ways, including the *Krebs cycle.
Deacon process A former process
for making chlorine by oxidizing hy-
drogen chloride in air at 450°C using
a copper chloride catalyst. It was
patented in 1870 by Henry Deacon
(1822–76).
deactivation A partial or complete
reduction in the reactivity of a sub-
stance, as in the poisoning of a cata-
lyst.
deamination The removal of an
amino group (–NH 2 ) from a com-
pound. Enzymatic deamination oc-
curs in the liver and is important in
amino-acid metabolism, especially in
their degradation and subsequent ox-
idation. The amino group is removed
as ammonia and excreted, either un-
changed or as urea or uric acid.
de Broglie, Louis-Victor Pierre
Raymond(1892–1987) French
physicist, who taught at the Sor-
bonne in Paris for 34 years. He is best
known for his 1924 theory of
wave–particle duality (see de broglie
wavelength), which reconciled the
corpuscular and wave theories of
light and proved important in quan-
tum theory. For this work he was
awarded the 1929 Nobel Prize.
de Broglie wavelength The
wavelength of the wave associated
with a moving particle. The wave-
length (λ) is given by λ= h/mv, where
h is the Planck constant, m is the
mass of the particle, and v its veloc-
ity. The de Broglie wave wasÜrst
suggested by Louis de Broglie in 1924
on the grounds that electromagnetic
waves can be treated as particles
(photons) and one could therefore
expect particles to behave in some
circumstances like waves. The subse-
quent observation of *electron dif-
fraction substantiated this argument
and the de Broglie wave became the
basis of *wave mechanics.debyeA unit of electric dipole mo-
ment in the electrostatic system,
used to express dipole moments of
molecules. It is the dipole moment
produced by two charges of opposite
sign, each of 1 statcoulomb and
placed 10–18cm apart, and has the
value 3.335 64 × 10 –30coulomb
metre. It is named after Peter Debye
(1884–1966).Debye, Peter Joseph William
(1884–1966) Dutch-born physical
chemist who worked on a number of
topics. He introduced the idea of elec-
tric dipole moments in molecules
and, in 1923, working with Erich
Hückel, he published the *Debye-
Hückel theory of electrolytes. Debye
was awarded the 1936 Nobel Prize
for chemistry.Debye–Hückel–Onsager theory
A theory providing quantitative re-
sults for the conductivity of ions in
dilute solutions of strong elec-
trolytes, which enables the
*Kohlrausch equation to be derived.
This theory can be stated as: K = A +
BΛ^0 m, where Λ^0 mis the limiting molar
conductivity.
A = z^2 eF^2 /3πη(2/εRT)½,
B = qz^3 eF/24πεRT(2/εRT)½,
where z is the charge of an ion, e is
the charge of an electron, F is Fara-
day’s constant, ηis the viscosity of
the liquid, R is the gas constant, T is
the thermodynamic temperature,
and q = 0.586 in the case of a 1,1 elec-
trolyte. The Debye–Hückel–Onsager
theory uses the same assumptions
and approximations as the
*Debye–Hückel theory and is also
limited to very dilute solutions (usu-
ally less than 10–3M) for which there
is good agreement between theory
and experiment. The modiÜcations163 Debye–Hückel–Onsager theory
d