amino acid as bipolar ion
amino acid as bipolar ion
although the amino acid are commonly shows as containing an amino group, H2NCHRCOOH, certain chemical and physical are not consist with structure.
a. the amino acid are nonvolatile crystalline solid which melts with decomposition at fairly high temperature .
They are insoluble in polar solvent lick petroleum-ether,ether ,Benzine , and highly soluble (quick) in water.
The aqueous solution behave like solution of substance of high dipole moment .
Acidity and bestiality constant are ridiculously low for the -COOH and -NH2 GROUP.
all the properties are quit constant with bipolar ion structure for amino acid (1).
the physical property melting point solubility highdipole moment are just what would be expected of such a salt.
ACID-BASE PROPERTY amino acid as bipolar ion
When it is realized that the measured Ka actually refers to the ammonium ion R-NH3+.
and Kb actually refers to the basic property of carbohydrate ion IN RCOO-
when solution of an amino acid is made alkaline ,the dipole’r ion (1) is converted in to anion (2)
the stronger base hydroxide-ion ,removes a proton from the ammonium ion and displace a weaker base, the amine.
when the solution of amino acid is made acidic , the bipolar ion (1) is converted in to the cation(3)
the stronger acid H3O+ gives up the proton to the carboxylet ion and displaced the weaker carboxylec acid .
in summery the acid group of a simple amino acid like glycine is -NH3+ not -COOH and the basic group is -COO- not -NH2.
we must kipt in mind that ions (2) & (3) which contain free -NH2 or -COOH are in equilibrium with dipoler ion (1)
consequently amino acid undergo reaction characteristic of amines and the carboxic acid .as ion(2) is removed by reaction with benzil-chloride .for e.x, the equilibrium shifted to supply more of ion (2) so that eventually the amino acid is compliantly benzoylated .
where feasible we can speed up a desired reaction by adjusting or besicityof the solution in such a way as to increase the concentration of the reactive species.
In: Theory · Tagged with: amino acid, bipolar ion