929 ORGANOSILICON
(b) Cycloolefins (unsaturated): cyclopenta-
organoleptic. A term widely used to describe
diene, cyclooctatetraene consumer testing procedures for food products, per-
(c) Cycloacetylenes (triple bond) fumes, wines, and the like in which samples of
various products, flavors, etc. are submitted to
2. Aromatic hydrocarbons (arenes): unsatu-
groups or panels. Such tests are a valuable aid in
rated compounds; hexagonal ring structure;
determining the acceptance of the products and thus
single and multiple fused rings
may be viewed as a marketing technique. They also
(a) Benzene group (1 ring)
serve psychological purposes and are an important
(b) Naphthalene group (2 rings)
means of evaluating the subjective aspects of taste,
(c) Anthracene group (3 rings)
odor, color, and related factors. The physical and
(d) Polycyclic group (steroids, sterols)
chemical characteristics of foods are stimuli for the
3. Heterocyclic: unsaturated; usually pentago-
eye, ear, skin, nose, and mouth, whose receptors
nal rings containing at least one other ele-
initiate impulses that travel to the brain, where per-
ment besides carbon
ception occurs.
(a) Pyrroles
(b) Furans
(c) Thiazoles
organometallic compound. An organic com-
(d) Porphyrins pound composed of a metal attached directly to
carbon (RM); such compounds have been prepared
III. Combinations of aliphatic and cyclic struc-
of practically all the metals, as well as with such
tures
nonmetals as silicon and phosphorus. Metallic salts
1. Terpene hydrocarbons
(soaps) of organic acids are excluded. Examples are
2. Amino acids (some are aliphatic and others
diethylzinc (the first known organometallic), Gri-
combinations)
gnard compounds such as methyl magnesium iodide
3. Proteins and nucleic acids (coiled or helical
(CH
3
MgI), and metallic alkyls such as butyllithium
formations)
(C
4
H
9
Li), tetraethyllead, triethyl aluminum, tetrabu-
IV. Organometallic compounds
tyl titanate, sodium methylate, copper phthalocya-
V. Synthetic high polymers, including silicones
nine, and metallocenes. Some are highly toxic or
Important areas of organic chemistry include poly-
flammable; others are coordination compounds. Re-
merization, hydrogenation, isomerization, fermen-
active and moderately reactive organometallic com-
tation, photochemistry, and stereochemistry. There
pounds will react with all functional groups; two
is no sharp dividing line between organic and inor-
major types of reaction in which they are involved
ganic chemistry; the two often tend to overlap.
are oxidation and cleavage by acids. Probably the
See inorganic chemistry.
most important organometallic reactions are those
involving addition to an unsaturated linkage. Many
of them are powerful catalysts and form useful coor-
“Organiclear” [Standard]. (methylene
dination complexes.
bisthiocyanate).
See catalysis; metallocene; coordination compound.
CAS: 6317-18-6. TM for wood preservative.
Use: To stop wood rot, termite attack, mildew, and
organophosphorus compound. Any organic
decay.
compound containing phosphorus as a constituent.
These fall into several groups, chief of which are the
following: (1) phospholipids, or phosphatides,
organoborane. A compound composed of an
which are widely distributed in nature in the form of
unsaturated organic group and a borane obtained by
lecithin, certain proteins, and nucleic acids; (2) es-
the hydroboration reaction. Such compounds are
ters of phosphinic and phosphonic acids, used as
useful catalytic reagents in organic syntheses of
plasticizers, insecticides, resin modifiers, and
some complexity, e.g., cis-ortrans-olefins, optical-
flame-retardants; (3) pyrophosphates, e.g., tetrae-
ly pure alcohols, alkanes, and ketones. Prostaglan-
thyl pyrophosphate, which are the basis for a broad
dins and insect pheromones have been synthesized
group of cholinesterase inhibitors used as insecti-
by this means. A particularly versatile example is
cides; (4) phosphoric esters of glycerol, glycol, sor-
triphenylboron, B(C
6
H
5
)
3
.
bitol, etc., which are components of fertilizers.
See hydroboration; carborane; borane.
While many of these compounds play an important
part in animal metabolism, those in group (3) are
toxic and should be handled with extreme care.
organoclay. (organopolysilicate). A clay such
as kaolin or montmorillonite, to which organic
organopolysilicate. See organoclay.
structures have been chemically bonded; since the
surfaces of the clay particles, which have a lattice-
organosilane. See organosilicon.
like arrangement, are negatively charged, they are
capable of binding organic radicals. When this type
of structure is in turn reacted with a monomer such
organosilicon. An organic compound in which
as styrene, a complex known as a polyorganosilicate silicon is bonded to carbon (organosilane). Such
graft polymer results. compounds were first made by Friedel and Crafts in