Dictionary of Chemistry [6th Ed.]

2HNO 3 + Cu →CuO + H 2 O + 2NO 2

This is followed by reaction between

the acid and the oxide:

2HNO 3 + CuO →Cu(NO 3 ) 2 + H 2 O

oxidizing agent (oxidant)A sub-

stance that brings about oxidation in

other substances. It achieves this by

being itself reduced. Oxidizing agents

contain atoms with high oxidation

numbers; that is the atoms have suf-

fered electron loss. In oxidizing other

substances these atoms gain elec-

trons.

oximesCompounds containing the

group C:NOH, formed by reaction of

an aldehyde or ketone with hydroxy-

lamine (H 2 NOH) (see illustration).

Ethanal (CH 3 CHO), for example,

forms the oxime CH 3 CH:NOH.

A

• Information about IUPAC nomenclature
  oxo-PreÜx indicating the presence
  of oxygen in a chemical compound.

oxoacidAn acid in which the

acidic hydrogen is part of a hydroxyl

group bound to an atom that is

bound to an oxo group (=O). Sul-

phuric acid is an example. Compare

hydroxoacid.

3-oxobutanoic acid (acetoacetic

acid)A colourless syrupy liquid,

CH 3 COCH 2 COOH. It is an unstable

compound, decomposing into

propanone and carbon dioxide. The

acid can be prepared from its ester,

*ethyl 3-oxobutanoate.

oxonium ionAn ion of the type

R 3 O+, in which R indicates hydrogen

or an organic group especially the

ion H 3 O+, which is formed when

*acids dissociate in water. This is also

called the hydroxonium ion or the

hydronium ion.

oxo process An industrial process

for making aldehydes by reaction be-

tween alkanes, carbon monoxide,

and hydrogen (cobalt catalyst using

high pressure and temperature).

oxyacetylene burner A welding

or cutting torch that burns a mixture

of oxygen and acetylene (ethyne) in a

specially designed jet. TheÛame tem-

perature of about 3300°C enables all

ferrous metals to be welded. For cut-

ting, the point at which the steel is

to be cut is preheated with the oxy-

acetyleneÛame and a powerful jet of

oxygen is then directed onto the

steel. The oxygen reacts with the hot

steel to form iron oxide and the heat

of this reaction melts more iron,

which is blown away by the force of

the jet.

oxycodoneAn opioid, C 18 H 21 N 2 ,

similar in structure to *codeine but

with a –OH group in codeine re-

placed by a carbonyl group. It is an

analgesic often used for the treat-

ment of chronic pain. It is also used

illegally and is a controlled substance

in most countries.

oxygenSymbol O. A colourless

odourless gaseous element belonging

to *group 16 (formerly VIB) of the pe-

riodic table; a.n. 8; r.a.m. 15.9994; d.

1.429 g dm–3; m.p. –218.4°C; b.p.

–183°C. It is the most abundant el-

ement in the earth’s crust (49.2% by

weight) and is present in the atmos-

phere (28% by volume). Atmospheric

oxygen is of vital importance for all

organisms that carry out aerobic res-

piration. For industrial purposes it is

obtained by fractional distillation of

oxidizing agent 394

o

R

R′

O

C +

H

H

NOH

ketone hydroxylamine

• H 2 O

oxime

R

R′

C

NOH

Oximes