The diazotization of sulfanilic acid reaction is carried out in water. Sulfanilic acid is insoluble in water normally, but when sodium carbonate is added the SO3H group is deprotonated and you get the sodium salt which is soluble in water. Now that the sulfanilic acid it can react with the nitroso anion to yield the diazonium salt.
Sodium carbonate (also known as washing soda or soda ash), Na2CO3
is a sodium salt of carbonic acid. It most commonly occurs as a
crystalline heptahydrate, which readily effloresces to form a white
powder, the monohydrate. Sodium carbonate is domestically well
known for its everyday use as a water softener. It can be extracted
from the ashes of many plants. It is synthetically produced in
large quantities from salt (sodium chloride) and limestone in a
process known as the Solvay process.The manufacture of glass is one
of the most important uses of sodium carbonate. When combined with
silica and calcium carbonate and heated to high temperatures, then
cooled rapidly, glass is produced. This type of glass is known as
soda lime glass.
Sodium carbonate is also used as a relatively strong base in various settings. For example, sodium carbonate is used as a pH regulator to maintain stable alkaline conditions necessary for the action of the majority of photographic film developing agents...
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group R-N2+ X- where R can be any organic residue such alkyl or aryl and X is an inorganic or organic anion such as a halogen. Diazonium salts, especially those where R is an aryl group, are important intermediates in the organic synthesis of azo dyes..
Reaction of amine with the nitrosonium ion gives a diazonium salt. The diazonium salt is usually made in situ since it is usually unstable. If the alkyl group is replaced with an aryl group, the salt is stable at 0 oC and reacts with various nucleophiles.