H 3 C(CH 2 )nCO 2 – M+H 3 C(CH 2 )nSO 3 – M+H 3 C(CH 2 )nN
(CH 3 ) 3 +X–(n> 7).The existence of distinct polar (hydrophilic) and non-
polar (hydrophobic) regions in the molecule promotes
the formation MICELLEs in dilute aqueous solution.
amphiprotic solvent Self-ionizing solvent possessing
both characteristics of BRONSTED ACIDs and BRONSTED
BASEs, for example H 2 O and CH 3 OH, in contrast to an
APROTIC SOLVENT.
amphoteric A CHEMICAL SPECIESthat behaves both
as an acid and as a base is called amphoteric.This
property depends upon the medium in which the
species is investigated: H 2 SO 4 is an acid when studied
in water, but becomes amphoteric in SUPERACIDs.
amphoterism The ability to react with both acids
and bases.
anabolism The processes of METABOLISMthat result
in the synthesis of cellular components from precursors
of low molecular weight.
anaerobe An organism that does not need dioxy-
gen for growth. Many anaerobes are even sensitive to
dioxygen. Obligate (strict) anaerobes grow only in
the absence of dioxygen. Facultative anaerobes can
grow either in the presence or in the absence of
dioxygen.
anaerobic Any organism or any environmental or
cellular process that does not require the use of free
oxygen. Certain bacteria such as the Actinomyces
israeli, Bacteroides fragilis, Prevotella melaninogenica,
Clostridium difficile, and Peptostreptococcus are
ANAEROBEs.
The term refers to an organism that does not need
dioxygen for growth. Many anaerobes are even sensi-
tive to dioxygen. Obligate (strict) anaerobes grow
only in the absence of dioxygen. Facultative anaerobes
can grow either in the presence or in the absence of
dioxygen.
See alsoAEROBIC.analog A DRUGwhose structure is related to that of
another drug but whose chemical and biological prop-
erties may be quite different.
See alsoCONGENER.anation Replacement of the LIGAND water by an
anion in a COORDINATIONentity.anchimeric assistance See NEIGHBORING-GROUP
PARTICIPATION.anemia Condition in which there is a reduction in
the number of red blood cells or amount of
HEMOGLOBINper unit volume of blood below the ref-
erence interval for a similar individual of the species
under consideration, often causing pallor and fatigue.anion An atom or molecule that has a negative
charge; a negatively charged ion.
See alsoION.anionotropic rearrangement(anionotropy) A rear-
rangement in which the migrating group moves with its
electron pair from one atom to another.anion radical SeeRADICAL ION.anisotropy The property of molecules and materials
to exhibit variations in physical properties along differ-
ent molecular axes of the substance.annelation Alternative, but less desirable, term for
ANNULATION. The term is widely used in the German
and French languages.annulation A TRANSFORMATION; involving fusion of
a new ring to a molecule via two new bonds. Someannulation 13