751 LEHMSTEDT-TANASESCU
Le Chatelier. (1850–1936). A French physical Herschbach. A former student of Herschbach, Lee
chemist, famous chiefly for his statement of the refined molecular-beam and laser techniques, com-
bining them with theory to perform definitive stud-
equilibrium principle (often known as Le Chateli-
ies of reactions of individual complex molecules.
er’s law). His work included investigations of ce-
Doctorate from University of California in 1965.
ments, alloys, and gaseous combustion. The princi-
ple may be stated: every system in equilibrium is
conservative and tends to resist changes upon it by
legal chemistry. (forensic chemistry). The ap-
reacting in such a way as to help nullify the imposed
plication of chemical knowledge and procedures to
change.
matters involving civil or criminal law and to all
questions where control of chemical compounds,
“Lecisun” [Lucas Meyer]. TM for a skin
products, or processes is vested in agencies of Fed-
friendly mineral sunscreen.
eral or state governments. Legal chemistry applies
to the following areas:
lecithin. C
8
H
17
O
5
NRR
′
, R and R
′
being fatty acid
(1) Crime detection: primarily identification of poi-
groups. Pure lecithin is a phosphatidyl choline. The
sons, of bloodstains, writing and typewriter inks,
lecithins are mixtures of diglycerides of fatty acids
and a host of miscible materials such as textile fibers
linked to the choline ester of phosphoric acid. The
from clothing, hair, skin, etc. A variety of analytical
lecithins are classed as phosphoglycerides or phos-
methods are used in police laboratories, including
phatides (phospholipids). Commercial lecithin is a
microscopes, spot tests, color reactions, and spectro-
mixture of acetone-insoluble phosphatides. FCC
photometry.
specifies not less than 50% acetone-insoluble matter
(2) Food, drugs, and cosmetics are under the control
(phosphatides).
of the U.S. Food and Drug Administration. New
Properties: Light brown to brown, viscous semili-
products and proposed additives must be submitted
quid with a characteristic odor. Partly soluble in
by the manufacturer and approved before being
water and acetone; soluble in chloroform and ben-
placed on public sale. Control of the manufacture of
zene.
illicit drugs is an important phase of legal chemistry.
Derivation: Usually from soybean oil, also from
(3) Pesticides are subject to Federal regulation. New
corn, other vegetable seeds, egg yolk, and other
products must be registered, labeling must be specif-
animal sources.
ic as to chemical composition, active and inert ingre-
Grade: Technical, unbleached, bleached; fluid, plas-
dients, and directions for use.
tic, edible, FCC, 96+% for biochemical or chroma-
(4) Marketing and competitive pricing of chemical
tographic standards.
products’ fair trade agreements and discriminatory
Use: Emulsifying, dispersing, wetting, penetrating
practices are also under Federal supervision (Robin-
agent, and antioxidant; in margarine, mayonnaise,
son-Patman Act). This includes mergers, tie-in
chocolate and candies, baked goods, animal feeds,
sales, and other merchandising practices.
paints, petroleum industry (drilling, leaded gaso-
(5) Interstate shipment and labeling of hazardous
line), printing inks, soaps and cosmetics, mold re-
chemicals is regulated by the Department of Trans-
lease for plastics, blending agent in oils and resins,
portation and the Federal Aviation Agency as well
rubber processing, lubricant for textile fibers.
as by state and local laws. See labeling, toxi-
cology.
lectin. A type of protein occurring in the seeds of
(6) Patent law comprises a vast body of legal prac-
certain plants, especially legumes, characterized by
tice and court decisions. The patent system is de-
unusual binding specificity; their precise function in
signed to protect inventions and new discoveries,
the plant is being researched. Studies have been
and most chemical companies retain legal counsel in
made on the molecular structure and carbohydrate
this field.
content of the lectin found in the European herb
(7) Water pollution is subject to federal regulations
sainfoin.
(Federal Water Pollution Control Act, 1956). This
covers the discharge of contaminating industrial
Leduc’s rule. States that the volume occupied
waste, sewage, oil, etc., into navigable streams and
by a gas mixture is equal to the sum of the volumes
their tributaries as well as into coastal waters.
occupied separately by each constituent at the same
(8) Flammability of fabrics.
temperature and pressure as the mixture.
(9) Use of volatile, toxic solvents on an industrial
scale.
LEED. Low-energy electron diffraction.
(10) Air pollution including gases and particulates
from industrial stacks and auto exhaust emissions.
lees. The sediment at bottom of wine storage tank.
Leeuwenhoek, van. See van Leeuwenhoek,
Lehmstedt-Tanasescu reaction. Preparation
Anton.
of acridones (and 10-hydroxyacridones) from o-ni-
trobenzaldehyde and a halobenzene in the presence
Lee, Yuan T. (1936– ). Awarded Nobel Prize of concentrated sulfuric acid containing nitrous acid
in chemistry in 1986 jointly with Polanyi and as catalyst.