diazotization reactions

Question 1

define diazotization reaction

Answer 1

is an analytical method in which the volume of sodium nitrite used to convert sample into diazonium salts is measured

Question 2

constituent of diazonium salt

Answer 2

R-N+ and X
where:R -alkyl or aryl group
N -nitrogen
X-organic or inprganic anion usually halogen

Question 3

another name for diazotization titrations

Answer 3

sodium nitrite titrations

Question 4

diazotization reaction is used for sample having_

Answer 4

primary aromatic amine

Question 5

a diazonium compound has what bond btn nitrogens

Answer 5

nitrogen to nitrogen triple bond

Question 6

temperature for stable diazonium salt

Answer 6

0-5 degree centigrade

Question 7

what are the types of diazotization titration

Answer 7

direct method
indirect method
reverse method
special method

Question 8

classification of amino groups based on their rate of diazotization

Answer 8

1.rapid;they dont contain any substituent group
examples aniline,toluidine
2.slow;are those containing substituen groups like sulfa,nitrous oxide,carboxylic groups
example;nitroaniline,sulfanilic and anthranilic acids

Question 9

function of KBr in diazotization titration

Answer 9

increases rate of titration reaction when the amino groupis a slow type

Question 10

a diazonium salt decomposes at elevated temperature to form?

Answer 10

phenol and nitrogen gas

Question 11

explain the principle of diazotization titration

Answer 11

nano2(sodium nitrite) is added to hcl to produce hno2 (nitrous acid) which then diazotizes the aromatic amino group.After endpoint excess nitrous acid forms a sharp blue color with starch-ki paste/paper

Question 12

explain mechanism of starch-KI paste as external indicator

Answer 12

at/after endpoint nitrous acid reacts with hydrogen iodide to form iodine.iodine reacts with KI from starch-KIpaste to form a triiodide complex(KI3) .the triodide complex enters the amylose chain found in starch(amylose and amylopectin) to form an intense blueblack coulored linear chain

Question 13

why is diazotization titr performed at low temperature

Answer 13

because at elevated temperature diazonium salt decomposes into phenol and nitrogen gas

Question 14

explain direct method

Answer 14

are carried out by treating one mole of drug with 3moles of acidic solution
0.1M NaNO2 is titrated against the solution of drug and acid and starch -KI paper determines the endpoint

Question 15

explain reverse method

Answer 15

is used in samples forming insoluble diazonium salts

a soln of amine and sodium nitrite are in burrette titrated against acid(hcl)

Question 16

explain indirect method

Answer 16

is used for amines forming diazonium cpnds with a color similar to nitrous acid
amino is diluted in acid and cooled then reacted with excess nano2 the outcome soln is measured accurately and placed in a burette then titrated against carbonate of alpha napthol. endpoint is determined by absence of napthol on a spot on a filter paper

Question 17

applications of diazotization titration

Answer 17

to produce water fast dyes
used in nano technology
preparation of hydrocarbons
used in assay of sulpha drugs
used in assay of other drugs like benzicaine,procane

Question 18

blue color with starch-KI paper should last for how many minutes?

Answer 18

1 minute