Article
Reference
Glossary of terms used in physical organic chemistry (IUPAC
Recommendations 1994)
MULLER, Paul
Abstract
This glossary contains definitions and explanatory notes for terms used in the context of
research and publications in physical organic chemistry. Its aim is to provide guidance on
physical organic chemical terminology with a view to achieve a far-reaching consensus on the
definitions of useful terms and on the abandonment of unsatisfactory ones. As a consequence
of the development of physical organic chemistry, and of the increasing use of physical
organic terminology in other fields of chemistry, the 1994 revision of the Glossary is much
expanded in comparison to the previous edition, and it also includes terms from cognate
fields. A few definitions have been refined, some others totally revised in the light of
comments received from the scientific community.
MULLER, Paul. Glossary of terms used in physical organic chemistry (IUPAC
Recommendations 1994). Pure and Applied Chemistry, 1994, vol. 66, no. 5, p. 1077-1184
DOI : 10.1351/pac199466051077
Available at:
http://archive-ouverte.unige.ch/unige:151920
Disclaimer: layout of this document may differ from the published version.
1 / 1
Pure
&Appl. Chem.,
Vol.
66,
No.
5,
pp.
1077-1184,1994.
Printed in Great Britain.
0
1994 IUPAC
INTERNATIONAL UNION
OF
PURE
AND APPLIED CHEMISTRY
ORGANIC CHEMISTRY DIVISION
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY*
GLOSSARY
OF
TERMS USED IN
PHYSICAL ORGANIC CHEMISTRY
(IUPAC Recommendations 1994)
Prepared for publication by
P. MULLER
DCpartement de Chimie Organique, UniversitC de Genbve, CH-1211 Genbve 4, Suisse
*Membership of the Commission during the period (1987-93) the report was drafted was as follows:
Chairman:
1987-93 P. Muller (Switzerland);
Secretary:
1987-91 M. P. Doyle (USA); 1991-93
W. Drenth (Netherlands).
Titular Members:
P.
N. I. Ahlberg (Sweden, 1987-91); E. A. Halevi (Israel,
1987-89); J. M. McBride (USA, 1987-93); V. Minkin (USSR, 1991-93);
0.
M. Nefedov (USSR,
1987-91); M. Oki (Japan, 1987-91); J. Shorter (UK, 1989-93); Y. Takeuchi (Japan, 1991-93); Z.
Rappoport (Israel, 1991-93);
Associate Members:
P.
N. I. Ahlberg (Sweden, 1991-93); T. A. Albright
(USA, 1987-91); W. Drenth (Netherlands, 1987-91); E. A. Halevi (Israel, 1989-93); R. A. Y. Jones
(UK, 1987-89); V.
I.
Minkin (USSR, 1987-91);
0.
M. Nefedov (USSR, 1991-93); C. Pemn (USA,
1991-93);
D.
Raber (USA, 1991-93); K. Schwetlick (GDR, 1987-89); Y. Takeuchi (Japan, 1987-91);
P. Van Brandt (Belgium, 1987-93); J. R. Zdysiewicz (Australia, 1989-93);
National Representatives:
J.-L. Abboud Mas (Spain, 1991-93); E. Baciocchi (Italy, 1989-93); M. V. Bhatt (India, 1989-91);
X.
Jiang (China,
1987-93); J. J. E. Humeres Allende (Brazil, 1991-93); P. Laszlo (Belgium,
1987-91);
D.
J. McLennan (New Zealand, 1987-91);
Z.
Rappoport (Israel, 1987-91); R. Sabbah
(France, 1989-93); B.
E.
Smart (USA, 1987-91); J. A. Silva Cavaleiro (Portugal, 1991-93); J. Suh
(Republic of Korea, 1989-93);
0.
Tarhan (Turkey, 1989-93); T. T. Tidwell (Canada, 1991-93);
M. Tisler (Yugoslavia, 1987-93);
J.
Zavada (Czechslovakia, 1987-89); J. Zdysiewicz (Australia,
Membership of the Working Party 1987-93:
Chairman:
P.
Muller (Switzerland);
Members:
P.
N. I. Ahlberg (USA), M. P. Doyle (USA), W. Drenth
(Netherlands), E. A. Halevi (Israel), R. A. Y. Jones (UK), J. M. McBride (USA), V. Minkin (USSR),
M.
Oki (Japan), Y. Takeuchi (Japan), J. R. Zdysiewicz (Australia).
Republication of this report is permitted without the need for formal IUPAC permission on condition that an
acknowledgement, with full reference together with IUPAC copyright symbol
(0
1994
IUPAC), is printed.
Publication of a translation into another language is subject to the additional condition of prior approval from the
relevant IUPAC National Adhering Organization.
1987-89).
1078
GLOSSARY
OF
TERMS
USED
IN
PHYSICAL ORGANIC CHEMISTRY
A
a
P
CP
e
Ea
G
H
h
K
KD
k
kB
lg
In
h
V
0
List
of
General
Symbols
pre-exponential factor in Arrhenius equation [see energy
of
actiuation).
order
of
reaction
with
respect to reactant
A,
or
Bronsted coemcient (see
order
of
reaction
Br0nsted
relation)
.
order
of
reaction
with
respect to reactant
B
or Bronsted coefficient (see
order
of
reaction
Brramted
relation).
heat capacity [at constant pressure).
base
of
natural logarithms (e
=
2.718).
energy of activation
(see
energy
of
actiuation).
Gibbs energy.
enthalpy
.
Planck constant.
Kelvin (unit
of
thermodynamic temperature).
equilibrium constant.
rate constant (see
order
of
reaction).
Boltzmann constant.
natural logarithm.
decadic logarithm.
wavelength.
frequency.
(superscript) relating to thermodynamic
standard
state.
pressure.
gas constant.
entropy.
second (unit
of
time).
summation.
thermodynamic temperature.
time.
rate
of
reaction (see
rate
of
reaction).
(superscript) relating to transition state.
See
&localization.
amount concentration
of
X.
See also
IUPAC
QUANTITIES
(1988).
Commission on Physical Organic Chemistry
1079
GLOSSARY
OF
TERMS USED
IN
PHYSICAL ORGANIC CHEMISTRY
2nd
Edition,
1994
Synopsis.
This glossary contains definitions and explanatory notes for terms
used
in
the
context of research and publications
in
physical organic chemistry.
Its
aim
is
to provide guidance on physical organic chemical terminology with a view to
achieve
a
far-reaching consensus on the definitions of useful terms and on the
abandonment of unsatisfactory ones.
As
a consequence of the development of
physical organic chemistry, and of the increasing use of physical organic
terminology in other fields of chemistry, the 1994 revision of
the
Glossary
is
much
expanded
in
comparison to the previous edition, and
it
also includes terms from
cognate fields. A few definitions have been refined, some others totally revised in the
light
of comments received from the scientific community.
INTRODUCTION TO
THE
1994
REVISION
General
Remarks
The
"Glossary of Terms Used In Physical Organic Chemistry" was published
in
provisional
form
in
1979 (IUPAC PHYSICAL. ORGANIC GLOSSARY (1979)) and in revised form in 1983. A
historical account of procedure and progress up to that
stage
was outlined in
the
provisional
publication. The
1983
revision incorporated modifications agreed by the IUPAC Commission
111.2 (Physical Organic Chemistry), partly
in
response to comments received since the
provisional publication.
The
terms defined in the 1983 Glossary
are
incorporated in the IUPAC
"COMPENDIUM
OF
CHEMICAL TERMINOLOGY
(1987)
(Victor Gold Book).
The
present revision was undertaken with the long-term objective of compiling a com-
pendium of organic chemical terminology. For
this
reason the criteria for inclusion of terms
were much expanded'. The criteria for the
1983
edition were that the
meaning
of
a
term was
either not given
in
non-scientific dictionaries or standard textbooks or differed significantly
from the deflnition
in
such reference works, or that the term was associated
with
some ambi-
guity or uncertainty
with
respect to
its
meaning. The present compendium
tries
to be com-
prehensive, but without including trivial terms and without redefining IUPAC approved terms.
In particular, terms from cognate fields which are used by physical organic chemists, are
included. The terminology for the various spectroscopic methods of interest to organic chemists
is
not treated
in
the
present document, except for some terms from
NMR
spectroscopy, but may
be the subject of
a
separate study.
As
a
matter of policy, named reactions (such
as
Diels-Alder)
and symbolic representation of reaction mechanisms
(SN1.
etc.) have been excluded with a few
exceptions. These topics have been treated in separate reports of
this
Commission (IUPAC
REACTION MECHANISMS (1989), IUPAC TERMINOLOGY FOR TRANSFORMATIONS (1989)).
The work has
been
coordinated with that of other Commissions within
the
Division of Or-
ganic Chemistry, which deal with terminology, (e.g., IUPAC PHOTOCHEMICAL GLOSSARY
(1988), and
its
revision (1992), Commission 111.3; IUPAC TERMINOLOGY OF
STEREOCHEMISI'RY (1993), joint project of Commissions
111.1
and 111.2, and IUPAC CLASS
NAMES
(1993).
joint project of Commissions 111.1 and
111.2),
and
with
that of Commission
1.5.
Discrepancies
in
the views between the Commissions have been eliminated. Whenever there
was overlap or disagreement between the 1983 glossary and one of
the
more recent ones, the
best available definitions were incorporated in the present text with
a
reference to their origin.
Otherwise
this
glossary was not expanded into areas where other Commissions or working
parties are already active. It
is
hoped that a merged compendium will be published after
approval of the various glossaries.
The aim of
the
Glossary
is
to provide guidance on physical-organic chemical terminology
with
a view to achieving
a
far-reaching consensus on the definitions of useful terms and the
abandonment of unsatisfactory ones. The Commission
is
anxious
to emphasize that it cannot
(and would not
wish
to) impose
rules
or restrictions which might hinder rather than help the
precise formulation of new ideas.
Generally speaking, operational definitions were preferred to definitions couched in terms
of theoretical models. We have tried to avoid taking sides on issues of scientific,
as
distinct from
semantic, disagreement.
The Commission
is
pleased to acknowledge the generous contributions of many scientists
who helped by proposing
or
defining new terms, or by criticizing existing ones.
The
following
have contributed to
this
revision:
1080
GLOSSARY
OF
TERMS
USED
IN PHYSICAL ORGANIC CHEMISTRY
I.P. Beletskaya
N.J.
Leonard
T.W. Bentley
R.M.
Magid
C.F. Bernasconi P.C.
Maria
E. Buncel
RT.
Myers
C.
Eabom
C.
Reichardt
J.F. Gal
J.D.
Roberts
S.
Hoz M.F. Ruasse
W.P. Jencks
H.
Zollinger
N.
Way
The Commission thanks Mrs.
M.
Wyss and
Dr.
S.
Motallebi for their help
in
the
preparation of the manuscript of
this
Glossary.
Arrangement, Abbreviations and
Symbols
The arrangement
is
simply alphabetical, terms beginning
with
Greek letters following
those beginning with Latin ones. Italicized words
in
the body of
a
definition,
as
well
as
those
cited at the end, point to relevant cross-references.
No
distinction
is
made between singular and
plural
in
cross-referencing. Literature references should direct the reader either to the original
literature where the term was originally defined, or to pertinent references where it
is
used.
Underlining of words means that the words should be emphasized in the particular context of
the entry. The appearance of
a
term
in
quotation marks
in
the body of
a
definition indicates
that
no further information will be found under that heading. Capitalized names indicate
references.
A
cross
(+)
against the title of an entry implies that the Commission recommends
dis-
continuation of the term.
In
accordance with general practice KekulC structures are normally used in
this
Glossary
to represent the formulae of aromatic compounds.
A
single hexagon with
a
full circle inside
is
used
in
cases where delocalization
is
qphasized.
A
full circle
is
also used in the case of
monocyclic aromatic ions, but fused aromatics are represented by KekulC structures, because
in
this
case each circle would imply the presence of
6
x
electrons in each hexagon. Thus
naphthalene with
two
circles would appear to have 12
x
electrons, while it has only
10
in
re-
ality.
Dashed lines indicate delocalization of positive or negative charge or of the spin of an
unpaired electron. Curved singly headed arrows represent formal movement of electron pairs,
while doubly headed arrows between formulae symbolize resonance.
In
accordance
with
previous IUPAC recommendations (IUPAC
QUANTITIES
(1988)) the
symbol
*
to indicate transition states ("double dagger")
is
used
as
a prefix to the appropriate
quantities, e.g.
ASG
rather
than
the more often used
A&.
Relative positions are indicated by post-slashed Arabic numerals. For example,
1/4/dibromo-additlon may refer to addition at positions 9 and
10
of anthracene, or at positions
2 and
5
of hexa-2,4-diene (IUPAC TERMINOLOGY FOR TRANSFORMATIONS (1989)).
Alphabetical Entries
abstraction
moval of an atom (neutral or charged) from
a
molecular entity. For example:
A
chemical
reaction
or
transformation,
the main feature
of
which
is
the bimolecular re-
CH3COCH3
+
(i-C3H7)2N-
-
(CH&OCH;?>-
+
(i-C3H7)2NH
(proton abstraction from acetone)
CH4
+
C1'
-
H3C'
+
HCl
(hydrogen abstraction from methane)
acceptor number
(AN)
acid
mica
or capable of forming a covalent bond
with
an
electron pair
(see
Lewis
acid.
See
detachment.
A
quantitative measure, devised by
GUTMA"
(1976). of
Lewis
acidity.
A
molecular entity or chemical species capable of donating
a
hydron (proton) (see
Br0nsted
See also
hard
mid.