FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
[See section 10, Rule 13]
RECOVERY OF DIMETHYLFORMAMIDE
AND OTHER SOLVENTS FROM
PROCESS STREAMS OF
MANUFACTURE OF TRICHLORO-GALACTOSUCROSE;
PHARMED MEDICARE PVT. LTD., A COMPANY INCOPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS 141 WALCHAND HIRACHAND MARG, MUMBAI - 400 001, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.

TECHNICAL FIELD
The present invention relates to methods of recovery of N-N-
dimethylformamide from process streams of production of
Trichlorogalactosucrose, i.e. I'-e'-Dichloro-l'-S'-DIDEOXY-p-
Fructofuranasyl-4-chloro-4-deoxy-galactopyranoside(TGS).
DESCRIPTION
The most economical way of recovery of DMF from the Process Streams of TGS manufacture is described wherein, the tertiary amide is adsorbed on to a Affinity chromatographic resin. The other impurities are washed away and pure DMF was eluted using suitable solvents.
The manufacture of TGS involves the protection of the 6th primary position of sucrose. This is done by first dissolving sucrose in a suitable solvent. The preferable solvent is a tertiary amide such as N-N-dimethylformamide (DMF), Dimethyl acetamide, etc. Further after the formation of the suitable 6-O-protected ester of sucrose, the chlorination is carried out using a Vilsmeier-Haack reagent (Vilsmeier reagent). This Vilsmeier reagent is generated by reacting a chlorinating reagent such as Thionyl chloride, Phosphorus oxychloride, Phosphorus pentachloride, etc with a tertiary amide such as N-N, Dimethylformamide, etc. The reaction is carried out with excess of DMF, so that DMF itself acts as a medium for carrying out the chlorination reaction.
The chlorination reaction forms TGS, the artificial sweetener along with various other chlorinated sugar derivatives as impurities. The solvent, DMF from the reaction mixture during the isolation of the TGS, has to be recovered. This DMF forms a substantial cost factor in the process costing for the manufacture of TGS. The economical way of solvent

recovery forms a part of process design, wherein the recovered solvent is free from impurities and can be re-used further for subsequent batch cycle. This is also necessary to avoid problem of handling of DMF in effluents from the point of pollution control.
However, high boiling point and decomposition when heated above 80-100°C are the properties of DMF or any tertiary amide which make a recovery of DMF difficult in conventional distillation systems.
When DMF is distilled off at lower temperatures under vacuum or distilled at higher temperatures, the energy cost associated with it is enormous. So it is impractical to recover DMF in an economical way by the process of conventional distillation.
In this particular invention we report use of resins with groups on them capable of selectively / preferentially adsorbing an organic solvent including DMF, and subsequent elution and recovery of the solvent in pure form. Here direct energy cost of solvent recovery is dramatically reduced and the quality of the solvent recovered is also higher in purity.
These resins are aromatically engineered synthetic adsorbents. The base synthetic material is styrene coupled with divinyl benzene. These specially crosslinked resins are highly porous and can hold large molecules in it and can also be eluted out easily. These resins are used for recovery or purification of variety of solvents. Attaching to these resins functional groups which have selective or preferential affinity towards the molecule of interest, here an organic solvent, serves the purpose of making them useful for selective adsorption and purification applications. In present work, such selective resins for solvents of interest shall be invented and a process standardized using them as a tool.

In preferred embodiment of the process, the process stream from the .TGS manufacture containing DMF is directly passed on through a chromatographic resin packed in a Stainless Steel (SS) column. The DMF process stream is passed at a particular flow rate as per the design considerations. The DMF selectively gets adsorbed to the resin and the other impurities with water pass through the outlet of the column. The resin is then washed to remove any adhering impurities. The DMF adsorbed in the resin is eluted out by suitable solvents such as methanol, acetone, etc. The DMF solvent mixture is then subjected to low temperature distillation and the pure DMF is recovered.
The process stream from the TGS manufacture could be DMF in any one of the following mixtures
a) DMF in aqueous solution
b) DMF in aqueous solution along with inorganic salts
c) DMF in aqueous solution along with TGS and other chlorinated sucrose derivatives
d) DMF in aqueous solution along with other chlorinated sucrose derivatives
e) DMF in aqueous solution containing TGS, inorganic salts and other chlorinated sucrose derivatives
f) DMF in other solvent or solvent mixtures containing inorganic salts
g) DMF in other solvent or solvent mixtures containing TGS and other chlorinated sucrose derivatives
h) DMF in other solvent or solvent mixtures containing other chlorinated sucrose derivatives

i) DMF in other solvent or solvent mixtures containing inorganic salts, TGS and other chlorinated sucrose derivatives
Same approach shall cover a solvent which can be used in alternative to
4
DMF including but not limited to a tertiary amide other than DMF such as Dimethyl acetamide used in Vilsmeier reagent preparation. This process also covers a solvent which is high boiling, which requires high energy cost to recover such solvents from process streams and is used in a process of production of TGS and is required to be removed and recovered from a process stream. This approach also covers in its scope general application of this approach for removal of solvents from process streams by adsorption on selectively / preferentially adsorbing functional groups attached to resins useful in column chromatography.
The results given below are an account of interim results, which shall be improved upon by further work and fine tuned until complete specification is submitted. The details of work done so far disclosed below serve as illustrations and do not limit the scope of actual techniques used, actual chemicals used, actual resins used or scope of reaction conditions or process conditions claimed. The techniques, the resins and the reaction conditions or process conditions disclosed below are subject matter of ongoing trials and fine tuning or trials in alternative or better conditions in method for recovery of DMF from process streams of various processes of TGS manufacture.
In one such experiment, 800 L of a process stream from TGS manufacture containing 15% of DMF and dissolved inorganic salts from chlorination was taken for DMF recovery.
The solution was passed through 1200 L of suitable resin packed in SS column. The solution was passed at a flow rate of 450 L/H. After the

solution was passed, the column was washed with 2400 L of DM water at 450 L/ H. Then the DMF was eluted with 1500 L of methanol.
The DMF along with methanol was collected from. the bottom of the column and was subjected to distillation at 45°C under vacuum for methanol removal. The DMF obtained was checked for purity by GC and was found to be 97.8%. The overall yield of DMF from the recovery stream was 95%.
Removal of a solvent, including DMF or its equivalent solvents from a process stream of manufacture of TGS is being reported here for the first time. In the proposed further work, this experiment shall be followed up with full investigation on this issue and a process be invented for removal of DMF or equivalent solvents from process stream of TGS preparation. This reaction shall also be evaluated for its general application for all types of similar processes where solvent recovery is necessary and has never been so far done by applying affinity chromatography.
Dated this 23rd day of May, 2006.
FOR PHARMED MEDICARE PVT. LTD. By their Agent
(DR. VASANTANANTRAO SAVANGIKAR) KRISHNA & SAURASTRI