Patent US4246171A successfully refreshed from Google Patents.
US4246171A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous diazotization process, wherein the rate of addition of inorganic nitrite is automatically controlled by polarovoltric means
Assignee: BASF Corp
•
Filing: 1978-09-07
•
Granted: 1981-01-20
•
Expires: 1998-09-07
Abstract
Abstract Automatically controlled continuous process for the diazotization or tetrazotization of aromatic amines in which the rate of addition of the inorganic nitrite is controlled by a polarovoltric method. The process comprises adding regularly and continuously to a reactor an aqueous slurry or solution of the amine containing sufficient acid for the diazotization process and simultaneously adding to the reactor a solution of an inorganic nitrite at a rate which is automatically regulated by a polarovoltric controller to ensure that a pre-selected concentration of unreacted nitrous acid is maintained in the reactor throughout the whole period of the reaction.
Inventors
- 👤 Alexander Hamilton
- 👤 Colin Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 19:48
CPC Classifications
C; C07; C07C; C07C245/00; C07C245/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
127 words
In a process for the diazotization of aromatic primary monoamines or diamines which comprises adding regularly and continuously to a reactor (1) an aqueous slurry or solution of the amine containing sufficient acid for the diazotization process and (2) a solution of an inorganic nitrite at a rate which is automatically regulated to ensure that a preselected concentration of unreacted nitrous acid is maintained in the reactor throughout the whole period of the reaction wherein the improvement comprises employing a polarovoltric controller to regulate the rate of addition of the inorganic nitrite so that the concentration of nitrous acid present in the reaction mixture can be controlled to any desired value within certain limits by variation of the polarizing current during the whole period of the reaction.
Claim 2
Dependent Claim
127 words
In a process for the diazotization of aromatic primary monoamines or diamines which comprises adding regularly and continuously to a reactor (1) an aqueous slurry or solution of the amine containing sufficient acid for the diazotization process and (2) a solution of an inorganic nitrite at a rate which is automatically regulated to ensure that a preselected concentration of unreacted nitrous acid is maintained in the reactor throughout the whole period of the reaction wherein the improvement comprises employing a polarovoltric controller to regulate the rate of addition of the inorganic nitrite so that the concentration of nitrous acid present in the reaction mixture can be controlled to any desired value within certain limits by variation of the polarizing current during the whole period of the reaction.
Claim 3
Dependent Claim
71 words
A process as claimed in claim 1 in which the rate of addition of inorganic nitrite is controlled by a pair of platinium electrodes which are polarized by connecting a suitable constant current across them, such that the presence of excess nitrite depolarises the electrodes and causes the voltage to drop sharply, the voltage variation being used to control the valve used for adding the nitrite solution to the reaction vessel.
Claim 4
Dependent Claim
17 words
A process as claimed in claim 2 in which the valve is controlled by an on/off switch.
Claim 5
Dependent Claim
20 words
A process as claimed in claim 2 in which the valve is controlled by continuously regulating the degree of opening.
Claim 6
Dependent Claim
39 words
A process as claimed in claim 1 in which there are used two or more reaction vessels in series with contents of one overflowing to the next in the series, each vessel being fitted with a polarovoltric control mechanism.
Claim 7
Dependent Claim
30 words
A process as claimed in claim 5 in which the last reaction vessel is used for fine adjustment of the reaction end-point by selecting a suitable setting on the controller.
Claim 8
Dependent Claim
39 words
A process as claimed in claim 1 in which there is used a multi-stage reactor which is a series of vessels in which a vertical tube is divided into a number of compartments by a series of horizontal plates.
Claim 9
Dependent Claim
21 words
A process as claimed in claim 1 in which the amine used is one which is diazotizable under aqueous acid conditions.
Claim 10
Dependent Claim
21 words
A process as claimed in claim 8 in which the amine used is 2:5-dichloraniline, 3,3'-dichlorbenzidine, 5-nitro-2-aminoanizole, 3-nitro-2-aminotoluene, 4-chloro-2-nitro-aniline or 4-amino-toluene-3-sulphonic acid.
Claim 11
Dependent Claim
20 words
A process as claimed in claim 1 in which the diazotising agent is sodium nitrite in combination with hydrochloric acid.
References Cited (Backward Citations)
BE540844A
Cited
US3117954A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |