Dictionary of Chemistry [6th Ed.]

those of coriander, cumin, lemon,

and samphire. It can be made by the

action of an alcoholic sulphuric acid

solution on pinene (the major com-

ponent of turpentine).

tertiary alcoholSee alcohols.

tertiary amineSee amines.

tervalent(trivalent)Having a va-

lency of three.

Terylene Tradename for a type of

*polyester used in syntheticÜbres.

teslaSymbol T. The SI unit of mag-

neticÛux density equal to one weber

of magneticÛux per square metre,

i.e. 1 T = 1 Wb m–2. It is named after

Nikola Tesla (1870–1943), Croatian-

born US electrical engineer.

tetrachloroethene A colourless

nonÛammable volatile liquid,

CCl 2 :CCl 2 ; r.d. 1.6; m.p. –22°C; b.p.

121 °C. It is used as a solvent.

tetrachloromethane (carbon

tetrachloride)A colourless volatile

liquid with a characteristic odour,

virtually insoluble in water but misci-

ble with many organic liquids, such

as ethanol and benzene; r.d. 1.586;

m.p. –23°C; b.p. 76.54°C. It is made

by the chlorination of methane (pre-

viously by chlorination of carbon

disulphide). The compound is a good

solvent for waxes, lacquers, and rub-

bers and the main industrial use is as

a solvent, but safer substances (e.g.

1,1,1-trichloroethane) are increas-

ingly being used. Moist carbon tetra-

chloride is partly decomposed to

phosgene and hydrogen chloride and

this provides a further restriction on

its use.

tetradecanoic acid (myristic acid)

A saturated carboxylic acid CH 3

(CH 2 ) 12 COOH; r.d. 0.86; m.p. 58.8°C;

b.p. 250.5°C (100 mmHg). Its glyc-

erides are found in nutmeg, palm oil,

and butter fat. Compounds are used

in cosmetics and skin-care prepara-

tions. The name comes from the

Latin name for nutmeg, Myristica fra-

grans.

tetraethyl leadSee lead(iv)

tetraethyl.

tetragonalSee crystal system.

tetrahedral angleThe angle be-

tween the bonds in a *tetrahedral

compound (approximately 109°for a

regular tetrahedron).

tetrahedral compoundA com-

pound in which four atoms or groups

situated at the corners of a tetrahe-

dron are linked (by covalent or coor-

dinate bonds) to an atom at the

centre of the tetrahedron. See also

complex.

tetrahedron A polyhedron with

four triangular faces. In a regular

tetrahedron all four triangles are con-

gruent equilateral triangles. It consti-

tutes a regular triangular pyramid.

tetrahydrateA crystalline hydrate

containing four moles of water per

mole of compound.

tetrahydrocannabinol (THC)The

main *cannabinoid found in the

plant Cannabis sativa, and the com-

pound largely responsible for its psy-

choactive effects. There have been

reports that use of THC has been

linked to the onset of psychotic

episodes in both healthy users and,

in particular, in schizophrenics. It

tertiary alcohol 522

t

3 CH O (CH 2 ) 4 CH 3

3 CH

CH 3

H

H

OH

Tetrahydrocannabinol