66711-21-5 Usage
Description
Used in Ophthalmology:
Apraclonidine is used as an antihypertensive agent for controlling elevations in intraocular pressure that can occur during laser surgery on the eye. Its primary mechanism of action may be related to a reduction of aqueous formation.
Used in Glaucoma Treatment:
Apraclonidine is used as a selective α2-agonist for treating glaucoma by reducing intraocular pressure. It is particularly effective in controlling intraocular pressure elevations during laser surgery.
Used in Spasticity Management:
Although not explicitly mentioned in the provided materials, apraclonidine may also find use in managing spasticity associated with conditions like multiple sclerosis or spinal cord injury, similar to tizanidine (Zanaflex), which stimulates 2-adrenergic receptors to decrease the release of excitatory amino acid neurotransmitters from spinal cord interneurons.
Originator
Alfadrops,Cipla Limited,India
Manufacturing Process
The preparation of p-aminoclonidine (apraclonidine) consists of 6 steps.
In the first step 2,6-dichloro-4-nitroaniline was converted to 2,6-dicloro-4-
nitrophenylisothiocyanate by addition of thiophosgene in toluene according to
the method described in Great Britain Patent No.: 1,131,780 (Beck et al.).
The second step involved the conversation of 2,6-dichloro-4-nitrophenylisothiocyanate
to 1-(2-aminoethyl)-3-(2,6-dichloro-4-nitrophenyl)-thiourea
ethylenediamine solvate. The solution of 2,6-dicloro-4-nitrophenylisothiocyanate
(432 g, 1.73 mol) in 2 L of toluene was added dropwise to the
cooled (0°C) solution ethylenediamine (244 ml, 3.66 mol, 2.1 eq.) in toluene
(4 L) under a nitrogen atmosphere. 2-Propanol (1 L) was added and after 5
minutes, the solid was collected by filtration, washed with 20% 2-
propanol/toluene, and dried to a constant weight of 602 g (94%). This
product is hygroscopic, mp 120°C (dec.).
The third step was the conversation of 1-(2-aminoethyl)-3-(2,6-dichloro-4-
nitrophenyl)-thiourea ethylenediamine solvate to 2-[(2,6-dicloro-4-
nitrophenyl)imino]imidazoline ethylenediamine solvate. (500 g, 1.35 mol) of
above prepared thiourea solvate was suspended with toluene (4 L) and was
heated at reflux for 15 hours. The mixture was cooled to 23°C and 1 M
aqueous hydrochloric acid (4 L) was added. After stirring for 10 min the
biphasic mixture was filtered to remove a sticky insoluble material. The
aqueous phase was neutralized to pH=7.0 using 50% NaOH. After stirring for
1 hour the yellow solid was collected by filtration, washed with water (4 L)
and t-butyl methyl ether (2 L) and dried in air to constant weight of 195 g
(52%), m.p. 289-292°C.
The fourth step was the conversation of 2-[2,6-dichloro-4-nitrophenyl)
imino]imidazoline (150 g, 0.55 mol) in methanol (1,5 L) to 2-[(2,6-dichloro-4-
aminophenyl)imino]imidazoline by hydrogen with 30 g Raney nickel catalyst at
23°C for 22 hours. After removing the catalyst hydrogen chloride gas was
bubbled into solution until pH of the reaction mixture was 1.0. The solvent
was rotary removed in vacuum and the residual solid was slurried with 2-
propanol (1 L). The solvent was again removed by rotary evaporation, the
cream solid was triturated with 2-propanol (600 ml). After aging for 1 hour,
the solid was collected by filtration, washed with 2-propanol and t-butyl
methyl ether, and dried for 15 hours at 6°C and t-butyl methyl ether, and
dried for 15 hours at 60°C and 20 mm Hg. Yield of dihydrochloride 167 g (96%), mp 260°C (dec.).
The dihydrochloride was converted to the monochloride (step 5) by adding 5
M aqueous sodium hydroxide dropwise to pH=6.5 at 5°C for 2 hours. Yield of
hydrochloride 87%.
The last step was recrystallization of product from water. The recrystallized
material had m.p. 300°C. Calculated for: C9H10Cl2N4HCl: C, 38.39; H, 3.94;
N, 19.90; Cl, 37.78. Found: C, 38.36; H, 3.91; N, 19.83; Cl, 37.77.
Veterinary Drugs and Treatments
Apraclonidine is an alpha2 adrenergic agonist used to reduce aqueous
humor secretion. Apraclonidine is a relatively selective, alphaadrenergic
agonist and does not have significant membrane stabilizing
(local anesthetic) activity. The onset of action is within 3 – 5
hours of a single dose. It apparently is less effective than brimonidine
in dogs and is very potent, causing vomiting and diarrhea in
cats and dogs. Apraclonidine will reduce aqueous production but
must be combined with other agents for adequate control. Neither
the beta-blockers nor alpha-agonists are as effective as the carbonic
anhydrase inhibitors in decreasing aqueous production.
Check Digit Verification of cas no
The CAS Registry Mumber 66711-21-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,6,7,1 and 1 respectively; the second part has 2 digits, 2 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 66711-21:
(7*6)+(6*6)+(5*7)+(4*1)+(3*1)+(2*2)+(1*1)=125
125 % 10 = 5
So 66711-21-5 is a valid CAS Registry Number.
InChI:InChI=1/C9H10Cl2N4.ClH/c10-6-3-5(12)4-7(11)8(6)15-9-13-1-2-14-9;/h3-4H,1-2,12H2,(H2,13,14,15);1H
66711-21-5Relevant articles and documents
A α2 - Adrenergic receptor agonist hydrochloric acid an le decides and its preparation method
-
, (2018/01/11)
The invention relates to an alpha2-adrenergic receptor stimulant apraclonidine hydrochloride and a preparation method thereof. The structural formula is shown in the specification. The preparation comprises the following steps: 2, 6-dichloro-4-nitroaniline, formic acid and acetic anhydride are mixed, heated and stirred, react and recrystallize, N-(2, 6-dichloro-4-nitrophenyl) formamide is obtained and then stirred, flows back and reacts with sulfuryl chloride and thionyl chloride, N-(2, 6-dichloro-4-nitrophenyl) dichlorocarbamide is obtained and dropwise added to an ethyl acetate solution containing ethylenediamine and triethylamine, the mixture is stirred for reaction for 1-10 h under the condition of 5-8 DEG C, 2-(2',6'-dichloro-4'- nitroanilino)-2-imidazoline is prepared, then a reducing agent is added to the solvent for reduction, hydrochloric acid is finally added to a reaction liquid, and stirring and backflow are performed for 1.5 h for preparation. The preparation process is simple to operate, the yield is high, the cost is low, the reaction route is short, little three wastes are generated, and industrial production is facilitated.
Process for preparation of clonidine derivatives
-
, (2008/06/13)
A novel process for preparing clonidine derivatives has been discovered which is shorter, less expensive and safer than previously known methods. A new thiourea complex has also been discovered which can be directly cyclized to produce the corresponding heterocyclic product.
Radioiodinated p-iodoclonidine: a high-affinity probe for the alpha 2-adrenergic receptor.
Van Dort,Neubig,Counsell
, p. 1241 - 1244 (2007/10/02)
The chemical synthesis of 2-[(2,6-dichloro-4-iodophenyl)imino]imidazolidine (PIC) and its radioiodinated analogue [125I]PIC is described. PIC was synthesized from 2,6-dichloroaniline in five synthetic steps. This agent displayed a high affinity for the alpha 2-adrenergic receptor (IC50 = 1.5 nM) in competitive binding assays conducted with purified human platelet plasma membrane fractions. For the synthesis of radioiodinated PIC the triazene intermediate 11 was synthesized from 2,6-dichloro-4-nitroaniline in five synthetic steps. Acid-catalyzed decomposition of 11 with no-carrier-added Na125I afforded high specific activity [125I]PIC. In view of its high affinity for the alpha 2-adrenergic receptor, [125I]PIC is a potentially useful probe for studies in adrenergic pharmacology.