Title of Invention

"AN IMPROVED METHOD OF EXTRACTING PURIFIED QUINOLINE FROM CRUDE QUINOLINE BASES"

Abstract The method comprises reacting crude quinbline bases, as obtained by fractional distination of coal'tar, with saturated solution of ammonium sulphate containing 8-10 wt«% free sulphuric acid, which is supplied continuously and counter-currently with the flow of the crude quinoline bases in a reactor, followed by neutralising the free acid in the recovered quinoline by adding 20-30% aqueous ammonia and removing excess moisture by adding toluene to obtain quinoline of more than 95% purity and less than 1% moisture. Reference : Figure 1 of the accompanying drawings.
Full Text The present invention relates to an improved method of extracting purified quinoline from crude quinoline bases.
The invention relates more particularly to an improved continuous process for recovering purified quinoline from crude quinoline bases as obtained by fractional distillation of coal-tar at 230 -270 ° C, by contacting the said crude quinoline bases continuously and counter-currently with a solution of ammonium sulphate containing 8-10% free sulphuric acid, allowing the acidic quinoline base sulphate formed to settle as bottom layer of the reactants, separating the bottom layer, neutralizing the same with 20-25% aqueous solution of ammonia to obtain pure quinoline bases after treating the recovered quinoline bases with toluene to reduce moisture content thereof to be less than 1% by weight.
Quinoline of purity more than 95% is required for the production of certain vital drug intermediates, preservatives and photo sensitive dyes, and is hence a chemical of high commercial value.
The existing method of extracting pure quinoline from crude quinoline bases is to contact the bases in batches with sulphuric acid of strength 20-30% in a number of separate steps. The existing method has a number of drawbacks, such as,
(a) unsaturated compounds and indole present in the crude quinoline bases are polymerized in the presence of free sulphuric acid of strength 20-30%, producing sludge which acts as an emulsion stabilizer to retard separation of the acidic quinoline base sulphate formed and the spent heavy oil in two distinct layers; (b) extracted quinoline bases are contaminated with oils; (c) the equipment used are corroded by the free sulphuric acid of strength 20-30% used; and (d) operations being performed in batches, involving a number of separate stages, the method is relatively slow and hence low cost-effective.
The object of the present invention to provide an improved continuous process for recovering / extracting quinoline of purity more than 95% from crude quinoline bases containing heavy oil and naphthalene oil, as obtained by fractional distillation of coal-tar, without causing corrosion of the equipment (used) by sulphuric acid of concentration of 20-30 wt. %, in a cost-effective way.

In the invented process the crude qulnoline bases containing heavy oil and naphthalene oil of boiling point 230-270%C obtained by fractional distillation of coal-tar are reacted with saturated solution of ammonium sulphate in water containing free sulphuric acid of strength 8-10% by weight counter-currently and continuously in one or two stages, settling the acidic quinoline sulphate formed as the bottom layer, and neutralisincj lie free acid in trie bottom layer with 20-25% aqueous solution of ammonia1 to obtain quinoline which is of more than 95% purity.
The fixation of quinoline with sulphuric acid to produce acidic quinoline base sulphate takes place according to reaction:
2 C9H7N + H2S04 -> (C9H7N)2H2S04
The neutralization of acidic quinoline base sulphate with aqueous ammonia solution takes place according to reaction:
(C9H7N)2H2SO4 + 2N H3 -» 2CgH7N + (NH4)2 SO4
The invented process is described fully and particularly in an unrestrictive manner with reference to the accompanying drawings in which
Figure 1 is a flow diagram of the process.
Referring to Fig. 1, crude quinojine base containing heavy oil and / or naphthalene oil of boiling point 230-270°C is transferred from tank (4) to reactor (1) by means of pump (3). Saturated solution of ammonium sulphate containing free sulphuric acid of strength 8-10% by weight is also transferred from tank (5) into reactor (1) continuously and counter-currently with the flow of the crude quinoline base by means of pump (3). Compressed air through line (2) and steam through line (7) are supplied into the reactor. The ingredients in the reactor are agitated for 5-6 minutes by means of a pneumatic stirrer provided in the reactor anp then allowed to settle therein for 5 to 10 hours. The acidic quinoline base sulphate settles as a reddish liquid in the bottom layer and spent heavy oil in the top layer. The acidic quinoline base sulphate in bottom layer is first drained out into tank (5) and then spent heavy oil in the top layer is drained out through line (8). 20-30% aqueous ammonia is added from tank (6) into tank (5) for neutralising the free acid in acidic quinoline base sulphate. Toluene in required quantity is then added into tank (5) for reducing moisture content of the acid neutralized quinoline to be less than 1% by weight. The quinoline produced is of more than 95% purity.
The excess solutions are discharged through line (9). Reactor (1) is of capacity 300 litre and each of tanks (4, 5 and 6) is of capacity 200 litre.
The addition of toluene reduces the moisture content of the recovered quinoline from 7 % to less than 1% and thereby restricts the chance of contamination of the recovered quinoline with inorganic salts.
The use of saturated solution of ammonium sulphate containing sulphuric acid of strength 8-10% in the invented process helps quick separation of the extracted quinoline from oil of crude bases by preventing formation of stable emulsion of quinoline and oil.
Aqueous ammonia added in the method acts as a buffer to prevent corrosion of the equipment by free sulphuric acid present in the saturated solution of ammonium sulphate added to the reactor.
Experiments have been carried out to determine the residual quinoline content of the spent oil with and without using saturated solution of ammonium sulphate for the recovery of quinoline from oil. It has been found that the residual quinoline content of spent oil is reduced from 1.8% by weight to 0.4-0.6% by weight by using the saturated solution of ammonium sulphate in the invented method.





We Claim: -
1. An improved method of extracting purified quinoline from crude quinoline
bases as obtained by fractional distillation of coal tar, characterized in that
the method comprises the following steps in sequence: -
(a) transferring the crude quinoline bases from tank (4) into reactor
(1) by means of pump (3);
(b) transferring saturated solution of ammonium sulphate containing
free sulphuric acid of strength 8-10% by weight from tank (5)
continuously and counter-currently with the flow of the crude
quinoline bases in quantity required to reduce quinoline content in
the crude quinoline bases from 1.8% to 0.4-0.6% by weight, into
reactor (1) by means of pump (3);
(c) supplying compressed air through line (2) and steam through line
(7) into reactor (1);

(d) agitating the ingredients in reactor (1) for 5-6 minutes by means
of a pneumatic stirrer provided therein;
(e) allowing the ingredients to settle in the reactor for 5 to 10 hours;
(f) draining out the reddish liquid separated in the bottom layer,
containing acidic quinoline base sulphate into tank (5);
(g) adding 20-30% aqueous ammonia from tank (6) into tank (5) for
neutralising the free acid therein; and
(h) adding toluene to tank (5) to reduce moisture content of the purified quinoline produced therein to be less than 1% by weight.
2. The method as claimed in claim 1, wherein the reactor (1) is of capacity
300 litre and each of tanks (4, 5 and 6) is of capacity 200 litre.


Documents:

709-del-1998-abstract.pdf

709-del-1998-claims.pdf

709-del-1998-correspondence-others.pdf

709-del-1998-correspondence-po.pdf

709-del-1998-description (complete).pdf

709-del-1998-drawings.pdf

709-del-1998-form-1.pdf

709-del-1998-form-19.pdf

709-del-1998-form-2.pdf

709-del-1998-form-4.pdf

709-del-1998-pa.pdf

abstract.jpg


Patent Number 244459
Indian Patent Application Number 709/DEL/1998
PG Journal Number 50/2010
Publication Date 10-Dec-2010
Grant Date 07-Dec-2010
Date of Filing 20-Mar-1998
Name of Patentee STEEL AUTHORITY OF INDIA LIMITED
Applicant Address ISPAT BHAWAN, LODHI ROAD, NEW DELHI-110003
Inventors:
# Inventor's Name Inventor's Address
1 HARSHRAJ KRISHNARAO CHATI INDIAN OF RDCIS, SAIL, RANCHI-834002
2 TILAKRAJ BHASKARRAO CHAHANDE INDIAN OF RDCIS, SAIL, RANCHI-834002
3 JAYANTI VINKATA SITARAMA MURTY INDIAN OF RDCIS, SAIL, RANCHI-834002
PCT International Classification Number C01B 25/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA