FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10 and rule 13]
Process for the preparation of disodium salt of (6R,7R)-7-
[[(2Z)-(2-Amino-4-thiazo]y})(methoxyim)no)acety)]amino]-8-
oxo-3-[[(l,2,5,6-tetrahydro-2-methyl-5,6-dioxo-l,2,4-triazin-3-
yl)thio]methyl]-5-thia-l-azabicyclo [4.2.0] oct-2-ene-2-carboxylie
acid hemiheptahydrate
CLARIS LIFESCIENCES LIMITED
Claris Corporate Headquarters, Nr.Parimal Crossing,
Ellisbridge, Ahmedabad - 380 006,
GUJARAT, INDIA
The following specification particularly describes the invention and the manner
in which it is to be performed.

DESCRIPTION
FIELD OF INVENTION
[0001] A process for the preparation of Disodium salt of (6R,7R)-7-[[(2Z)-(2-Amino-4-thiazolyl) (methoxyimino) acetyl] amino] - 8 - oxo - 3 - [[(l,2,5,6-tetrahydro-2-methyl-5,6-dioxo-l,2.4-triazin-3-yl)thio]methyl]-5-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid hemiheptahydrate.
BACKGROUND OF THE INVENTION
[0002] A. Cephalosporin
[0003] Cephalosporin is a group of broad-spectrum derived from species of fungi of the genus Cephalosporium and is related to the penicillin in both structure and mode of action but relatively penicillinase-resistant antibiotics. These antibiotics have low toxicity for the host,-considering their, broad antibacterial spectrum. They have the active nucleus of beta-lactam ring, which results in a variety of antibacterial and pharmacological characteristics when modified mainly by substitution at 3 and 7 positions.
[0004] Cephalosporin gives antibacterial activities by inhibition of mucopeptide synthesis in the cell wall. Cephalosporin widely used in the treatment of gonorrhea, meningitis. pneumococcal, staphylococcal and streptococcal infections. The cephalosporin class of antibiotics is usually divided into generations by their antimicrobial properties. Three generations of cephalosporins are recognized and the fourth has been grouped. Fifth & sixth generation are under the phase study.
[0005] Each newer generation of cephalosporins has broader range of activity against gram-negative organisms but a narrower range of activity against gram-positive organisms than the preceding generation. The newer agents have much longer half-life resulting in the decrease of dosing frequency. Accordingly, the third-generation cephalosporins can penetrate into tissues well, and thus antibiotic levels are good in various body fluids. Examples are cefoperazone, cefotaxime, ceftriaxone, ceftazidime, ceftizoxime, and moxalactam.

[0006] B.Cdftriaxone
[0007] Ceftriaxone is an antibiotic belonging to a group of antibiotics called the cephalosporins. Ceftriaxone belongs to the third generation cephalosporin. It is used for fighting bacteria in the body. Ceftriaxone kill bacteria by interfering with the ability of bacteria to form cell walls. The bacteria therefore break up and die. Ceftriaxone is given by injection or infusion, and is generally used for severe infections.
INDICATION
[0008] Administration of the Ceftriaxone once or twice daily has been effective for the patient with meningitis, while dosage once a day has been effective for other infection. About half the ceftriaxone can be recovered from the urine, the remainder appears to be eliminated by biliary secretion. A single dose of Ceftriaxone (125 to 250 mg) is effective in the urethral, cervical, rectal, or pharyngeal, gonorrhea, including disease caused by penicillin producing microorganism.
[0009] The third generation cephalosporins, either with or without aminoglycosides, have been considered to be the drug of choice for the serious infection caused by klebsiella, Enterobacter, Proteus, Providencia, Serratia, and Haemophilus species. Ceftriaxone is now the therapy of choice for all forms of gonorrhea and for severe" forms of Lyme disease. Ceftriaxone is used for the initial treatment of meningitis in nonimmunocompromised adult and children older than 3 months because of their antimicrobial activity, good penetration into cerebrospinal fluid and record of clinical successes. They are the drug of choice for the treatment of meningitis caused by the Haemophilus influenzae, sensitive Streptococcus pneumoniae, Neisseria meningitidis, and gram-negative enteric bacteria.
STATEMENT OF THE INVENTION
A process for the preparation of disodium salt of (6R,7R)-7-[[(2Z)-(2-Amino-4-thiazolyl) (methoxyimino) acetyl] amino] - 8 - oxo - 3-[[(l,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triazin-3-yl)thio]methyl]-5-thia-I-azabicyclo[4.2.0] oct - 2 - ene - 2 -carboxylic acid hemiheptahydrate. comprising:

a) condensation of 7 -amino - 3 - {( 2, 5 - dihydro - 6 - hydroxy - 2 - methyl - 5 - oxo -
1. 2, 4 -triazin-3- yl) thiomethyl}-3-cephem-4-carboxylic acid (7-ACT) with condensing agent such as organic base in organic solvent in presence of a compound selected from S- (2-benzothiazolyl-2-(2-aminothiazol-4-yl)-2-methoxyimino thioacetate (MAEM), 2-mercapto-5-memyl-l,3,4-thiadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyimino acetate and 2-mercapto-5 -phenyl-1,3,4-oxadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxy imino acetate at a temperature between 0 to 30 °C for a duration of 10 and 30 min under constant stirring;
b) extraction of above condensed mixture with water and separating the aqueous layer;
c) addition of sodium hydrosulphite. sodium hypochlorite, EDTA and activated
charcoal within 20 min at a temperature between 0 to 30 °C into the aqueous layer and maintain degassing under vacuum for 15 to 45 min and then filtered; d)salt formation is done by drop wise addition of aqueous solution of compound selected from sodium acetate trihydrate, sodium-2-ethyl hexanoate, anhydrous sodium acetate, sodium carbonate, sodium bicarbonate and sodium hydroxide to the filtrate obtained at step (c) for 15 to 45 min:
e) isolation and crystallization of disodium salt formed at step (d) is done by the
addition of organic solvent under constant stirring for 30 to 120 min;
f) after complete crystallization, filter the product obtained at step (e) by vacuum
filtration and wash the cake with chilled acetone and water mixture; &
g) after washing collect the wet cake and dry it under vacuum at temperature between
40°C and 50°C for 2 to 5 hours.
The condensing agent in step (a) is selected from various organic bases such as triethyl amine. 2,3 or 4-picoline, 1,4-dimethyl piperazine, N-ethylpiperidine, N-methyl morpholine, trimethyl aniline, pyridine, dimethyl amino pyridine, N-methyl piperidine, N-methyl pyridine, N-ethyl dimethyl aniline, diethyl amine, N-ethyldimethyl amine, diisopropyl ethyl amine, N,N-dimethyl aniline and tributyl amine preferably it is triethyl amine. The organic solvent used in step (a) is selected from chlorinated hydrocarbons such as dichloromethane and nitriles preferably it is dichloromethane. The compound used at step (a) for condensation used is S- (2-

benzothiazolyl-2-(2-aminothia2ol-4-yl)-2-methoxyimino thioacetate (MAEM). The compound used for salt formation at step (d) is sodium acetate trihydrate. The organic solvent used in step (e) is selected from acetone, ],4-dioxane, isopropyl alcohol and ethanol. The ratio of chilled acetone: water mixture used in step (f) for washing is 9:1.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Definitions
[0011] Antibiotics
[0012] An antibiotic is a chemical compound that inhibits or abolishes the growih of microorganisms or Antibiotics are substances produced by various species of microorganism (bacteria, fungi, actinomycetes) that suppress the growth of other microorganisms.
[0013] Synthesis
[0014] Synthesis is commonly understood to be an integration of two or more preexisting elements, which results in a new creation. Synthesis is the process of producing a chemical compound (usually by the union of simpler chemical compounds). In Chemistry chemical synthesis is the process of forming a particular molecule from chemical precursors.
[0015] Broad Spectrum
[0016] Broad-spectrum antibiotics give activity against a wide range of disease caused by bacteria. Broad-spectrum antibiotics are properly used in the Empirically prior to identifying the causative bacteria when there is a wide differential and potentially serious illness would result in delay of treatment.
[0017] Narrow spectrum
[0018] Narrow spectrum drugs target a specific group of microorganisms and are able to

interfere with a metabolic process specific to those organisms. Narrow-spectrum antibiotic acts against only specific families of bacteria.
[0019] Gram-Positive bacteria:
[0020] Gram-positive bacteria are large group of rod-shaped bacteria that retains the crystal violet stain when treated by Gram's method. Gram-positive bacteria are characterized by having as part of their cell wall structure peptidoglycan as well as polysaccharides and/or echoic acids. The peptidoglycans that are sometimes also called murein are heteropolymers of glycan strands, which are cross-linked through short peptides.
[0021] Gram-negative bacteria:
[0022] Gram-negative bacteria gives lose crystal violet stain but are stained pink when treated by Gram's method. In Gram-positive bacteria, the crystal violet Stain is trapped by the layer of peptidoglycan, which forms the outer layer of the cell.In Gram-negative bacteria, the outer membrane prevents the stain from reaching the peptidoglycan layer in the periplasm. The outer membrane is then perineabilized by acetone treatment, and the pink safranin counterslained is trapped by the peptidoglycan layer.
[0023] Gram's Method:
[0024] Gram's Method is a staining technique used to classify bacteria: those that retain the gentian violet are gram-positive and those that do not retain it are gram-negative. In 1884, Hans Christian Gram, a Danish doctor working in Berlin, accidentally stumbled on a method which still forms the basis for the identification of bacteria. While examining lung tissue from patients who had died of pneumonia, he discovered that certain stains were preferentially taken up and retained by bacterial cells. Over the course of the next few years, Gram developed a staining procedure, which divided almost all bacteria into two large groups - the Gram stain.
[0025] Individual bacterial cells are hard to see, partly because they are small, but also because they are almost transparent. In addition to magnification under a microscope,

optical tricks must also be used to be able to see them.
[0026] A process for the preparation of Disodium salt of (6i?,7J?)-7-[[(2Z)-(2-Amino-4-
thiazoIyI)(methoxyimino)acetyI]amino]-8-oxo-3-[[(IJ2.5,6-tetrahydro-2-methyl-5.6-dioxo-
1,2,4-triazin-3-yl)thio]methyl]-5-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
hemiheptahydrate as follows:
[0027] A suspension is preparing by using 1543.24 grains of 7-amino-3- {(2,5- dihydro-6-hydroxy-2-methyl-5-oxo-1.2,4-triazin-3-yl)thiomethyl}-3-cephem-4-carboxylic acid (7-ACT) and 40.5783 Fluid ounce ( fl.oz) of an appropriate solvent which may includes various inert solvents like e.g. halogenated, e.g. chlorinated hydrocarbons, e.g. dichloromethane: nitriles; preferably dichloromethane etc.
[0028] As per the step [0027], the suspension should have a free slurry type good consistency.
[0029] As per the step [0028], the color of suspension is ranging between white to pale yellow.
[0030] As per the step [0027], during the reaction the temperature is ranging between 0°C and 30°C.
[0031] As per the step [0030], the temperature is ranging between 0°C and 10°C.
[0032] As per the step [0030], the temperature is ranging between 10°C and 20°C.
[0033] As per the step [0030], the temperature is ranging between 20°C and 30°C.
[0034] As per the step [0033], add 2.7931 flog of Triethyl amine with constant stirring within 30 min. under control temperature.
[0035] As per the step [0034], the addition time is ranging between 10 to 30 minutes.
[0036] As per the step [0035], the addition time is ranging between 10 to 15 minutes.

[0037] As per the step [0035], the addition time is ranging between 15 to 20 minutes. [0038] As per the step [0035], the stirring time is ranging between 20 to 25 minutes.
[0039] As per the step [0035], the addition time is ranging between 25 to 30 minutes.
[0040] As per the step [0034], the Triethyl amine is an organic base, which is used as condensing agent. The examples of various organic bases are 2.3 or 4-picoline, 1,4-dimethyl piperazine, N-ethylpiperidine, N-methyl morpholine, Tri methyl aniline, pyridine. Dimethyl amino pyridine, N-methyl piperidine, N-methyl pyridine, N-ethyl dimethyl aniline, Diethyl amine, N-ethyldimethyl amine, diisopropyl ethyl amine. N,N-dimethyl aniline and Tributyl amine etc.
[0041 ] As per the step [0040], the reaction mass is stir between 15 and 45 min at the same temperature.
[0042] As per the step [0041], the time is ranging between 15 and 20 min.
[0043] As per the step [0041], the time is ranging between 20 and 25 min.
[0044] As per the step [0041], the time is ranging between 25 and 35 min.
[0045] As per the step [0041], the time is ranging between 35 and 45 min.
[0046] As per the step [0041], Add 1608.056 grains S- (2-benzothiazolyl-2-(2-ammothiazol-4-yl)-2-methoxyimino thioacetate (MAEM) portion wise within 30 min. other than MAEM, 2-mercapto-5-methyl-l,3,4-thiadiazolyl-(Z)-2-(2-aminoihiazol-4-yl)-2-metho xyimino acetate or 2-mercapto-5 -phenyl-l,3,4-oxadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-metho xyimino acetate can also be used.
[0047] As per the step [0046], the time for addition is ranging between 5 and 30 min. Under control temperature and stirring.

[0048] As per the step [0047], the time is ranging between 5 and 10 min.
[0049] As per the step [0047], the time is ranging between 10 and 20 min.
[0050] As per the step [0047], the time is ranging between 20 and 30 min.
[0051] As per the step [0047], the control temperature is between 0°C and 30°C.
[0052] As per the step [0047] and [0051], the control temperature is ranging between 0°C and 5°C.
[0053] As per the step [0047] and [0051], the control temperature is ranging between 5°C and 10°C.
[0054] As per the step [0047] and [0051], the control temperature is ranging between 10°Cand20°C.
[0055] As per the step [0047] and [0051], the control temperature is ranging between 20°Cand30°C.
[0056] As per the step [0046], Monitor reaction by High Performance Liquid Chromatography (HPLC) up to 7-ACT less than 2% observed.
[0057] As per step [0056], the extraction is done by using 11.83 floozy & 8.45 fl.oz of water.
[0058] As per the step [0057], mix both the extracted aqueous layer and backwash with 16.90 11. oz dichloromethane.
[0059] As per the step [0058], separate the aqueous layer.
[0060] As per the step [0059], Collect aqueous layer & adjust temperature between 0°C and 30°C.

[0061 j As per the step [0060], the temperature is ranging between 0°C and 10°C.
[0062] As per the step [0060], the temperature is ranging between 10°C and 20°C.
[0063] As per the step [0060], the temperature is ranging between 20°C and 30°C.
[0064] As per the step [0060]. add 77.16 grains sodium hydrosulphite.
[0065] As per the step [0060], add 0.16 floozy Sodium hypochlorite.
[0066] As per the step [0060], add 15.4324 grains Ethylenediaminetetraacetic acid disodiumsalt (EDTA).
[0067] As per the step [0060], add 154.32 grains good quality Charcoal.
[0068] As per the step [0064], [0065], [0066] and [0067] is added into the step [0060] within 20 min.
[0069] As per step [0068], maintain degassing under vacuum for 15 to 45 min. at the same temperature.
[0070] As per the step [0069], the time is ranging between 15 and 20 min.
[0071] As per the step [0069]. the time is ranging between 20 and 25 min.
[0072] As per the step [0069], the time is ranging between 25 and 30 min.
[0073] As per the step [0069], the time is ranging between 30 and 35 min.
[0074] As per the step [0069], the time is ranging between 35 and 40 min.
[0075] As per the step [0069], the time is ranging between 40 and 45 min.

[0076] As per the step [0069], after degassing filter the charcoal from aqueous layer.
[0077] As per the step [0076], collect the filtrate after charcoal filtration.
[0078] As per the step [0077], chilled it between 0°C and 20°C temperature.
[0079] As per the step [0078]. the temperature is ranging between 0°C and 5°C.
[0080] As per the step [0078]: the temperature is ranging between 5°C and 10°C.
[0081] As per the step [0078]. the temperature is ranging between 10°C and 15°C.
[0082] As per the step [0078], the temperature is ranging between 15°C and 20°C.
[0083] As per step [0078], Add Sodium acetate trihydrate aqueous solution dropwise with constant stirring containing 1180.56 grains of Sodium acetate trihydrate in 5.41 floozy of water at same temperature. Instead of sodium acetate trihydrate, sodium-2-ethyl hexanoate. anhydrous sodium acetate, sodium carbonate, sodium bicarbonate and sodium hydroxide can be used for salt formation.
[0084] As per the step [0083], the addition time is ranging between 15 to 45 min.
[0085] As per the step [0084], the time is ranging between 15 and 20 min.
[0086] As per the step [0084], the time is ranging between 20 and 25 min.
[0087] As per the step [0084], the time is ranging between 25 and 30 min.
[0088] As per the step [0084], the time is ranging between 30 and 35 min.
[0089] As per the step [0084], the time is ranging between 35 and 40 min.
[0090] As per the step [0084], the time is ranging between 40 and 45 min.

[0091] As per the step [0083], the mass is collected and put on the temperature between 10°Cand30°C.
[0092] As per the step [0091], the temperature is ranging between 10°C and 20°C.
[0093] As per the step [0091 ], the temperature is ranging between 20°C and 25°C.
[0094] As per the step [0091 ], the temperature is ranging between 25°C and 30°C.
[0095] As per the step [009]]. add 228.99 floozy Acetone in to the mass with control addition under stirring at same temperature to isolate the product from aqueous solution. Instead of Acetone, 1,4-dioxane, isopropyl alcohol and ethanol can be used for isolation of the product.
[0096] As per the step [0095], the limit of control addition is between 90 to 120 min.
[0097] As per the step [0096]. the limit of control addition is between 90 to 100 min.
[0098] As per the step [0096]; the limit of control addition is between 100 to 110 min.
[0099] As per the step [0096], the Jimit of control addition is between 110 to 120 min.
[0100] As per the step [0095], stirring the reaction mass for 30 to 120 min. at the same temperature for complete isolation as well as crystallization.
[0101] As per the step [0100], after complete crystallization, filter the product by vacuum filtration.
[0102] As per the step [0101], wash the product by using 16.90 floozy chilled Acetone: Water (9:1) mixture.
[0103] As per the step [0102], wash the product by using 11.49 floozy chilled acetone.

[0104] As per the step [0103], Collect the wet cake after washing.
[0105] As per the step [0104], dry it at temperature between 40°C and 50°C under vacuum for 2 to 5 hours.
[0106] As per the step [0105], the temperature is ranging between 40°C and 45°C.
[0107] As per the step [0106], the temperature is ranging between 45°C and 50°C.
Example:
A process for the preparation of Disodium salt of (6R,7R)-7-[[(2Z)-(2-Amino-4-lhiazolyl) (methoxyimino) acetyl] amino] - 8 - oxo - 3-[[(l,2.5,6-tetrahydro-2-methyl-5,6-dioxo-1.2,4-triazin-3-y])thio]methyl]-5-thia-l-a2abicyclo[4.2.0] oct - 2 - ene - 2 -carboxylic acid hemiheptahydrate. which can be describe as follows:
1. The first step is Condensation:
1.1 A suspension is preparing by using 1543.24 grains of 7 -amino - 3 - {( 2, 5 - dihydro -6 - hydroxy - 2 - methyl - 5 - oxo - 1, 2, 4 -triazin-3- yl) thiomethyl}-3-cephem-4-carboxylic acid (7-ACT) and 40.5783 fl.oz dichloromethane;
1.2 As per the step 1.1. the temperature is ranging between 0°C and 30°C;
1.3 As per the step 1.2, add 2.7931 fl.oz of Triethyl amine with constant stirring within 20 min. under control temperature;
1.4 As per the step 1.3, the time for addition is ranging between 10 and 30 min;
3.1 As per the step 1.4, reaction mass is stir between 15 and 45 min. at the same temperature;
1.1 As per the step 1.5, Add 1608.056 grains S- (2-benzothiazolyl-2-(2-aminothiazol-4-yl)-2-methoxyimino thioacetate (MAEM) portion wise into the reaction mass;
1.2 As per the step 1.6, the time for addition is ranging between 5 and 30 min. Under control temperature and stirring;
1.3 As per the step 1.7, the temperature is increase between 0°C and 30°C;
1.4 As per the step 1.8, Monitor reaction by HPLC up to 7-ACT less than 2% observed.

2. The second step is Extraction:
2.1 As per step 2, the mass collected from step 1. mixture was extracted with 11.83 fl.oz &8.45 fl.oz of water;
2.2 As per the step 2.1, combine both extracted aqueous layer and backwash with 16.90 fl.oz dichloromethane;
2.3 As per the step 2.2 separate the aqueous layer.
3. The third step is Charcoal addition:
3.1 As per the step 3. Collect aqueous layer from step 2 and adjust the temperature of aqueous layer;
3.2 As per the step 3. J, adjust the temperature between 0°C and 30°C;
3.3 As per the step 3.1. add 77.16 grains sodium hydro sulphite;
3.4 As per the step 3.1, add 0.16 fl.oz Sodium hypochlorite;
3.5 As per the step 3.1, add 15.4324 grains EDTA;
3.6 As per the step 3.1, add 154.32 grains Charcoal;
3.7 As per the step 3.3,3.4.3.5 & 3.6, add all these into step 3.1;
3.8 As per step 3.7, maintain degassing under vacuum for 15 to 45 min. at the same temperature;
3.9 As per the step 3.8, after degassing filter the charcoal from aqueous layer.
4. The forth step is Salt formation:
4.1 As per the step 4, collect the filtrate after charcoal filtration from step 3;
4.2 As per the step 4.1, chilled the reaction mass between temperature 0°C and 20°C; 3.1 As per step 4.2, Add Sodium acetate trihydrate aqueous solution dropwise with
constant stirring containing 1180.56 grains of Sodium acetate trihydrate in 5.41 fl.oz of water at same temperature; 4.4 As per the step 4.3, the time for addition is ranging between 15 and 45 min.
5. The fifth step is Isolation:
5.1 As per the step 5, the mass collected from step 4.0 is put on the temperature between 10°Cand30°C;
5.2 As per the step 5.1 add 228.99 fl.oz Acetone in to the mass with control addition under stirring at same temperature to isolate the product from aqueous solution;
5.3 As per the step 5.2. for control addition the time is ranging between 90 and 120 min:

5.4 As per the step 5.3, stirring the reaction mass for 30 to 120 min. at the same temperature for complete isolation as well as crystallization.
6. The sixth step is Filtration:
6.1 As per the step 6. after complete crystallization, filter the product from step 5 by vacuum filtration;
6.2 As per the step 6.1, wash the product by using 16.90 fl.oz chilled Acetone: Water (9:1) mixture;
6.3 As per the step 6.2, wash given to the Product by 11.49 fl.oz of Chilled Acetone.
7. The seventh step is Drying:
7.1 As per the step 7, collect the wet cake from step 6 after washing;
7.2 As per the step 7.1 dry it under vacuum at temperature between 40°C and 50°C for 2 to 5 hours.

We claim,
1. A process for the preparation of disodium salt of (6R,7R)-7-[[(2Z)-(2-Amino-4-thiazoly]) (methoxyimino) acetyl] amino] - 8 - oxo - 3-[[(1.2,5;6-tetrahydro-2-methyl-5,6-dioxo-l;2,4-triazin-3-yl)thio]methyl]-5-thia-l-azabicyclo[4.2.0] oct - 2 - ene - 2 -carboxylic acid hemiheptahydrate. comprising:
a) condensation of 7 -amino - 3 - {( 2, 5 - dihydro - 6 - hydroxy - 2 - methyl - 5 -oxo - 1, 2, 4 -triazin-3- yl) thiomethyl}-3-cephem-4-carboxylic acid (7-ACT) with condensing agent such as organic base in organic solvent in presence of a compound selected from S- (2-benzothiazolyl-2-(2-aminothiazol-4-yl)-2-methoxyimino thioacetate (MAEM). 2-niercapto-5-methyl-l,3,4-thiadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyimino acetate and 2-mereapto-5 -phenyl-1.3,4-
b) oxadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxy imino acetate at a temperature between 0 to 30 °C for a duration of 10 and 30 min under constant stirring;
c) extraction of above condensed mixture with water and separating the aqueous layer;
d) addition of sodium hydrosulphite, sodium hypochlorite. EDTA and activated charcoal within 20 min at a temperature between 0 to 30 °C into the aqueous layer and maintain degassing under vacuum for 15 to 45 min and then filtered;
e) salt formation is done by drop wise addition of aqueous solution of compound selected from sodium acetate trihydrate, sodium-2-ethyI hexanoate, anhydrous sodium acetate, sodium carbonate, sodium bicarbonate and sodium hydroxide to the filtrate obtained at step (c) for 15 to 45 min;
f) isolation and crystallization of disodium salt formed at step (d) is done by the addition of organic solvent under constant stirring for 30 to 120 min:

g) after complete crystallization, filter the product obtained at step (e) by vacuum filtration and wash the cake with chilled acetone and water mixture; &
h) after washing collect the wet cake and dry it under vacuum at temperature between 40°C and 50°C for 2 to 5 hours.
2. A process for the preparation of disodium salt as claimed in claim 1, wherein the condensing agent is selected from various organic bases are trielhyl amine, 2,3 or 4-picoline, 1,4-dimethyl piperazine. N-ethylpiperidine, N-methyl morpholine, trimethyl aniline, pyridine, dimethyl amino pyridine, N-methyl piperidine, N-methyl pyridine, N-ethyl dimethyl aniline, diethyl amine, N-ethyldimethyl amine, diisopropyl ethyl amine, N,N-dimethyl aniline and tributyl amine.
3. A process for the preparation of disodium salt as claimed in claim 1 or 2, wherein The condensing agent is triethyl amine.
4. A process for the preparation of disodium salt as claimed in claim 1. wherein the organic solvent used in step (a) is selected from chlorinated hydrocarbons such as dichloromethane and nitriles.
5. A process for the preparation of disodium salt as claimed in claim 1, wherein the organic solvent used in step (a) is dichloromethane.
6. A process for the preparation of disodium salt as claimed in claim 1. wherein the compound at step (a) for condensation used is S- (2-benzothiazo]yl-2-(2-aminothiazo]-4-yl)-2-methoxyimino thioacetate (MAEM).
7. A process for the preparation of disodium salt as claimed in claim 1, wherein the compound used for salt formation at step (d) is sodium acetate trihydrate.
8. A process for the preparation of disodium salt as claimed in claim 1, wherein the organic solvent used in step (e) is selected from acetone, 1,4-dioxane, isopropyl alcohol and ethanol.
9. A process for the preparation of disodium salt as claimed in claim 1, wherein the ratio of chilled acetone: water mixture used at step (f) for washing is 9:1.

10. The process for preparation of disodium salt of (6R,7R)-7-[[(2Z)-(2-Amino-4-thiazolyl) (methoxyimino) acetyl] amino] - 8 - oxo - 3-[[(1.2,5,6-telrahydro-2-methy]-5,6-dioxo-1,2,4-triazin-3-yl)thio]methyl]-5-thia-l-azabicyclo[4.2.0] oct - 2 -ene-2-carboxylic acid hemiheptahydrate as claimed in any of the preceding claims and as substantially described with reference to the foregoing example.