Ketone is a class of chemical compounds contain the carbonyl group in which the
carbon atom is covalently bonded to an oxygen atom.
Carbonyl groups are:
Aldehydes (X and Y = H; X = H, Y = alkyl or aryl)
Ketones (X and Y = alkyl or aryl)
Carboxylic acids (X = OH, Y = H, alkyl, or
aryl)
Esters (X = O-alkyl or aryl; Y = H, alkyl, or aryl)
Amides (X = NH,
N-alkyl, or N-aryl; Y = H, alkyl, or aryl)
Acid halides
Acid anhydrides
Lactones
Lactams
Ketone has the general formula
RCOR' where the groups R and R' may be the same or different, or incorporated
into a ring (R and R' are alkyl, aryl, or heterocyclic radicals). The simplest
example, R and R´ are methyl group, is acetone (also called 2-propanone,
CH3COCH3) which is one of the most important ketones used in industry (low
molecular weight ketones are general purpose solvents.) In the IUPAC system, the
suffix -one is used to describe ketone with the numbering of the carbon atom at
the end that gives the lower number. For example, CH3CH2COCH2CH2CH3 is named
3-hexanone because the whole chain contains six carbon atoms and the oxygen is
connected to the third carbon from the lower number. There are aromatic ketones of which acetophenone and bezophenone are examples. Ketones can be made by the
oxidation of secondary alcohols and the destructive distillation of certain
salts of organic acids. In addition to as polar solvents, ketones are important
intermediates in the syntheses of organic compounds such as alkoxides,
hydroxyalkynes, imines, alcohols (primary, secondary as well as tertiary),
acetals, thioacetals, phosphine oxides, geminal diols, hydrazones, organic
sulfite and cyanohydrins.
Methyl Ethyl Ketone is a clear low viscosity liquid with a mild acetone like
odor; miscible in oil, soluble in water. It is used as a general solvent in
vinyl films and nitrocellulose coatings. It is used in manufacturing plastics,
textiles and paints.
SALES
SPECIFICATION
APPEARANCE
Clear
liquid
PURITY
99.5%
min
COLOR.
APHA
10
max
WATER
0.05%
max
NONVOLATILES
0.002%
max
DISTILLATION RANGE
79
- 80.5 C
TRANSPORTATION
PACKING
160kgs
in drum
HAZARD
CLASS
3
(Packing Group: III)
UN
NO.
1193
OTHER
INFORMATION
European
Hazard Symbols: F XI, Risk Phrases: 11-36-66-67, Safety Phrases:
9-16
GENERAL
DESCRIPTION OF SOLVENT
Solvent is a substance, usually a liquid, that acts as a dissolving agent or
that is capable of dissolving another substance. In solutions of solids or gases
in a liquid, the liquid is the solvent. In all other homogeneous mixtures (i.e.,
liquids, solids, or gases dissolved in liquids; solids in solids; and gases in
gases), solvent is the component of the greatest amount. The minor proportion
substances are called solutes. The solvent offers several functions during a
chemical reaction. It solves not only the substance that reacts with another one
to produce a new set of substances (reactant) but also the compound that
supplies the molecule, ion, or free radical, which is considered as the
attacking species in a chemical reaction (reagent). The solvent is conductive to
collisions between the reactants and reagents to transform the reactants to new
products. The solvent also takes roll of temperature control, either to provide
the energy of the colliding particles for speedy reaction and to absorb heat in
exothermic reaction. The appropriate solvent should be selected based on the
inactivity in the reaction conditions, dissolving the reagents as well as
reactants, appropriate boiling point and easy removal at the end of the
reaction.
Polarity
The most common solvent is water. Other common
solvents which dissolve substances that are insoluble (or nearly insoluble) in
water are acetone, alcohol, formic acid, acetic acid, formamide. BTX, carbon
disulfide, diemthyl sulfoxide, carbon tetrachloride, chloroform, ether,
tetrahydrofuran, furfural, hexane and turpentine. They may be classified as
polar and non-polar. Polar solvents, like water, have molecules whose electric
charges are unequally distributed, leaving one end of each molecule more
positive than the other. Usually polar solvent has O-H bond of which water
(HOH), (CH3OH) and acetic acid (CH3COOH) are examples.
Propanol, butanol, formic acid, formamide are polar solvents. Dipolar solvents
which contain a C-O solid bond without O-H bond are acetone [(CH3)2C=O], ethyl
acetate (CH3COOCH2CH3), methyl ethyl ketone, acetonitrile, N,N-dimethylformamide
and diemthyl sulfoxide. Nonpolar solvents, like carbon tetrachloride (CCl4),
benzene (C6H6), and diethyl ether ( CH3CH2OCH2CH3), have molecules whose
electric charges are equally distributed and are not miscible with water. Hexane, tetrahydrofuran and methylene chloride are non-polar solvents. Polar
solvents are hydrophilic but non-polar solvents are lipophilic. Polar reactants
will dissolve in polar solvents. Non-polar solvents dissolve non-polar compounds
best. Oil and water don't mix but separate into two layers. There are three
measures of the polarity as "dipole moment", "dielectric constant" and
"miscibility with water". Though low dipole moments and small dielectric
constants indicates non-polar solvents, sharp boundaries between polar and
non-polar solvents are not available. The polarity reflects the balance between
a polar component (OH) and a non-polar hydrocarbon component, existing in the
same molecule. If hydrocarbon character increases relatively, the polarity
decreases. On an operational basis, solvents that are miscible with water are
polar.
Polar Protic and Dipolar Aprotic
Protic refers to a hydrogen atom
attached to an electronegative atom. Protic solvents can donate an H+ (proton)
since they contain dissociable H+, such as hydrogen attached to oxygen as in a
hydroxyl group, nitrogen as in a amine group. Examples are water, methanol,
ethanol, formic acid, hydrogen fluoride and ammonia. Aprotic solvents don't has
O-H bond but a C=O bond typically. Examples are acetone [(CH3)2C=O] and ethyl
acetate (CH3COOCH2CH3). Polar protic solvents are useful in SN1 reaction, while
polar aprotic solvents are SN2 reaction.
