US2791492A - Apparatus for introducing alkali metal into closed systems - Google Patents

Description

y 7, 1957 H. s. ISBELL 2,791,492

APPARATUS FOR INTRODUCING ALKALI METAL INTOCLOSED SYSTEMS Filed April 21., 1955 70 VACUUM INVENTOR Horace (5T [sbell BY ArrRA/Ev AGENT APPARATUS FDR INTRGDUCING ALKALI METAL HNTO CLOSED SYSTEMS Horace S. Isbeli, Washington, D. C., assignor to the United States of America as represented by the Secretary of Commerce Application April 21, 1955, Serial No. 503,038

4 iCl-aims. (Cl. 23-=-259) This invention relates to chemical reaction systems and particularly to apparatus for introducing micro quantities of air and moisture sensitive reagents into a closed reaction system without contamination of either the reagent being introduced or the material in the system. The apparatus contemplated by the present invention is particularly efiicacious when employed for the methylation of organic materials such as polysaccharides.

Many synthetic and analytical processes require the introduction of measured quantities of sodium, potassium, lithium, calcium, and other air and moisture sensitive materials into reaction systems. Satisfactory procedures are available for the introduction of macro quantities of the materials, but the methods for use with micro quantities are inadequate. For example, when using methyl iodide as a methylative agent, no particular problem is involved since large quantities of such reagent are readily available. With the development of tracer chemistry, however, it is necessary to employ techniques whereby extremely minute quantities of radioactive materials such as radioactive methyl iodide can eflicaciously be employed. Moreover, in research involving bacteria polysaccharides for example, extremely small quantities of test material must be dealt with and the normal losses due to air and water contamination occurring in the process of introducing reagents cannot be tolerated. The present invention provides an apparatus for conducting chemical reactions involving minute quantities of materials and reagents.

It is therefore an object of the present invention to provide an apparatus for the successive introduction of small accurately measured quantities of reagents into closed reaction systems without loss by contamination.

A further object of the present invention is to provide an improved apparatus for the satisfactory methylation of organic materials in small quantities such as may be involved, for example, in the utilization of carbon-14 labelled methyl iodide.

Further objects will become apparent upon reference to the specification and drawings in which:

Fig. 1 shows a preferred embodiment of the present invention in the form of an apparatus designed for the methylation of small quantities of organic materials;

Figs. 2 and 3 are enlarged views of the reagent dispeusing portion of the apparatus shown in Fig. l, and

Fig. 4 shows a portion of the capillary type of reagent container employed.

The apparatus according to the present invention includes a reagent dispensing device 1 which comprises a fitting 2 having a centrally located stopcock type of valve 3. The fitting is further provided with a tapered joint 4 at each end to facilitate connecting with other portions of the apparatus to be described. A vapor bypass channel 5 is provided connecting the ends of the fitting opposite the valve 3.

The valve 3 is detailed in enlarged section in Figs. 2 and 3 of the drawings, and is shown as including a hollow body portion containing an internal rotatable gat- States Patent 0 ice ing member 3a. The gate 3a is transversely bored as indicated to provide a first-through passage 3b and a second transverse passage 30. The body portion 3 of the valve is provided with conventional ports 3d cooperably related to the passages in the gate member.

Fig. 4 shows the capillary tube reagent container employed for metering predetermined quantities of the reagent in connection with the dispensing valve detailed in Figs. 2 and 3. The reagent container comprises a thinwalled capillary tubing which has been drawn out to a desired size in a known manner. The tubing 6 is shown in enlarged size in Fig. 4 for purposes of clarity and the drawn-out neck portion is indicated as 60. Tubing having a uniform bore is employed, the size being chosen commensurate with the quantities of reagent which are required in a particular reaction process. For any particular application, the size of the neck portion of the capillary tubing is made to conform approximately to the size of the passageway 3b in the stopcock employed. The neck portion 6a of the capillary tube is then filled as indicated preferably by drawing the molten reagent R into the tube by means of suction and allowing the molten reagent to solidify. The filled container may then be stored for subsequent application to the apparatus of Fig. 1.

it is apparent that the quantity of the reagent R carried in the capillary tube is proportional to the amount of reagent per unit length. As indicated in Fig. 2, in order to dispense a desired amount of the reagent R, one end or" the capillary tubing 6a is introduced into the passage .ib of the valve-gate 3a. The valve-gate may then be rotated, severing a desired length of the capillary, until the transverse passage 3b is aligned with the upper and lower ports 3d of the stopcock. The end of the capillary tubing containing a measured quantity of the reagent in the severed portion is isolated from the remainder of the capillary tubing by the sealing action afforded by the valve-gate when it has been rotated to the position indi cated in Pig. 3. The contents of the severed section may then be introduced into the system to be described by a simple flushing procedure.

Inasmuch as the quantity of reagent per unit length in the capillary tube can be determined beforehand with great precision, the exact quantity of the material to be dispensed can be very accurately controlled, merely by measuring the length of the tubing which is severed by the stopcock duringa dispensing operation. For convenience in measuring, a suitable scale member S may be provided adjacent the reagent container 6 as shown in Fig. 1. By measuring the length of tubing from a fixed datum such as D, to the protruding end of the tube before and after insertion into the dispensing valve, the quantity of reagent introduced into the system can be very accurately regulated.

As shown in Figs. l and 2, the dispensing valve 3 includes a gas lock lie in the form of a channel which extends i'rom one of the orifices 3d in the valve body. Such channel is slightly larger than the diameter of the. portion 6 of the capillary tube. A rubber sleeve 23 snugly engages the outside diameters of the channel 3e and the capillary tube and serves the combined functions of sealing the gas lock 3e and frictionally securing the capillary container.

Fig. 1 shows an apparatus according to the present invention it may be employed for the methylation of anorganic compound. As shown in Fig. l, a reflux condenser 3. is provided having a coolant chamber 8a and an annular well portion 8b. The lower end of the well is connected to the upper connection 4 of the fitting 2. The lower end of the fitting, 2 is secured to any suit-able. reaction chamber 9 containingthe compound. The upper 3 end of the well portion of the reflux condenser 8 is connected by means of a valve 10 to a feedline 11.

In accordance With the apparatus of the present invention, the feedline 11 is provided with a first branch 11:: which is connected by means of a valve 12 to a vacuum source including trap 13 and a second branch 11b which is connected to a flask 14.

The apparatus shown in Fig. 1 further includes a gas burette 15 which is connected by means of a two-way valve 16 and connection 20 to the described reaction chamber 9, and, through connection 19 and valve 17 to a supply flask or receptacle 18. The valve 17 is in turn connected to valve 12 leading to the referred to vacuum trap 13. A magnetic stirrer 21 having an armature 21a mounted within the reaction chamber 9 is provided and suitable manometers 22 and 23 are indicated for regulating the feed of flow into the reflux condenser and for measurement of pressure.

The described apparatus may be employed for the methylation of organic materials in the following manner:

1. The material to be methylated as, for example 4 mg. of a bacterial polysaccharide such as dextran is placed in the reaction chamber 9 which is connected to the dispensing mechanism 1 -as described. The chamber 8a of the reflux condenser 8 is then filled with a suitable coolant such as Dry Ice or a mixtureof Dry Ice and a liquid, the melting point of which corresponds to a desired temperature. A flask 18 is provided containing radioactive methyl iodide and the flask 14 is connected to a source of dry ammonia.

2. The capillary reagent container 6a,. prepared as described, is then inserted into the gas trap guide channel 3e so that the neck portion may subsequently be inserted Within the passage 3b of the valve gate when the valve is in the position indicated in .Fig. 2. The rubber gasket or sleeve S serves as a seal for the gas lock channel 32. With the dispensing stopcock turned to the position of Fig. 2 the system may now be evacuated, and then made vacuum tight by means of valve 12. It will be apparent from Fig. 2, that in the indicated position of the dispensing stopcock, communication is established from the annular space between the channel 3e comprising the gas lock and the capillary tube and the transverse passage 30 of the stopcock valve. In this manner such space may also be evacuated to prevent subsequent contamination.

3. The dispensing stopcock is then turned to the position indicated in Fig. 3 and the valve 10 is now opened to permit the flow of ammonia from the reservoir 14 to the annular well of the reflux condenser. About ml. of liquid ammonia is thereby permitted to enter the reaction vessel 9 as a result of the condensation produced by the condenser. When sufficient ammonia has been admitted, the valve is closed. It will be noted that the solid reagent R in the capillary container is effectively sealed 01f from the reaction system at this point by the valve-gate 3a.

4. The magnetic stirrer 21 is then started and the valve is turned back to the position indicated in Fig. 2. With the stopcock in such position, a metered length of the neck portion 6a of the capillary container may now be inserted in the long passage 3b of the stopcock valve 3a. By means of the scale member, any predetermined amount of reagent contained in the capillary tube container may readily be measured otf. Since the gas trap 3e has already been evacuated, no contamination of the solid reagent R will occur. The valve is then rotated to the position of Fig. 3 as described, to sever the measured length of the capillary container. Since a head of liquid ammonia is present above the stopcock the reagent as well as the severed portion of the tube will be Washed down into the reaction vessel 9 at such time. In the present example, the capillary container was prepared so that a lfl-millimeter measured length would contain 0.1

millimole of metaHic sodium. In the described example it was found that one IO-millimeter addition of metallic sodium comprising the reagent in the capillary container was sufiicient to react with the hydroxyl groups of the material in the reaction vessel 9 and leave sodium in excess as shown by the characteristic blue color of sodium dissolved in the liquid ammonia. Any residue of the reagent contained in the severed segment of the capillary tube will of course be leached out by the liquid ammonia in the reaction vessel 9 as a result of the action of the magnetic stirrer.

5. In the example chosen, after 1 /2 hours, the reaction vessel 9 was cooled with liquid nitrogen and, by means of the gas burette 15, 4.9 ml. of methyl iodide at 380 mm. pressure as determined by the barometric pressure less the difference in the levels of the mercury in the burette and in the leveling bulb was introduced into the reaction vessel 9 from the flask 18 through burette 15. The amount of methyl iodide used corresponds to the sodium added plus an excess of 10%.

6. The temperature of the reaction mixture in the chamber was then allowed to rise and reaction continued for 2 hours under ammonia reflux. 7. The dispensing valve 3 was then again operated in the described manner to sever additional measured lengths of the capillary tube until a permanent blue color was obtained in flask 9.

8. Reaction was then allowed to continue 2 hours after which the equivalent amount (0.04 millimole) of methyl iodide was introduced from flask 18 through the =burette 15. After 2 hours of refluxing at liquid ammonia temperature, the valve 10 was adjusted to direct the ammonia back to the reservoir 14 and the condenser 8 and reaction vessel 9 was allowed to come to room temperature.

9. Valve 10 was then opened to the atmosphere and the methylated dextran in the reaction chamber 9 was extracted with a suitable solvent such as chloroform, washed with water and evaporated to dryness. The residual methylated dextran was hydrolyzed and chromatographed. The chromatogram showed that the dextran had been stisfactorily methylated.

The described methylation procedure is particularly valuable for the methylation of polysaccharides available in small quantities. Complete methylation of a sample of dextran, for example, in accordance with the described method required 4 to 8 successive additions of sodium and methyl iodide with separation of the partially methylated product by chloroform extraction after the fourth addition. The amount of methyl iodide used was far less than the amount heretofore used in conventional methods such as is employed in methylating macro preparations.

The procedure described also makes practicable the utilization of carbon-14 labeled methyl iodide for methylation and thereby opens the way .for structural studies of polysaccharides available in milligram quantities.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made within the scope of invention as defined in the appended claims.

What is claimed is:

1. In a chemical reaction process requiring the intro duction of solid reagents into a closed, evacuated reaction system having a reaction chamber and a solvent source, means for introducing said solid reagent into said reaction chamber comprising a frangible capillary tube container carrying a measured amount of said solid reagent, a dispensing device connected to the inlet of said reaction chamber comprising means for normally sealing the inlet to said reaction vessel, means for receiving a portion of said frangible tube, and means for concurrently severing a measured length of said capillary tube and establishing a connection between said severed portion, said solvent source and said reaction chamber.

. 2. The invention as defined in claim 1 in which said solid reagent dispensing device comprises a valve having ports communicating with said solvent source, said reaction chamber and said frangible container respectively, and selectively positionable gating means for establishing communication between said solvent source and said reaction chamber in one selected position and for establishing comunication between said frangible container and said reaction vessel in another of said selected positions.

3. The invention as defined in claim 2 in which said dispensing device includes a gas lock for receiving said frangible container, means for sealing said gas lock, and said gating means includes a first passage adapted to receive a portion of said frangible container when selectively positioned in a first position communicating with said gas lock and a second passage establishing communication between said first passage and said reaction chamber when said gating means is in said first position.

4. An apparatus for a chemical reaction process requiring the addition of a solid reagent into a closed, evacuated reaction system comprising, a reaction chamber, means connected to said reaction chamber for evacuating said apparatus, a solvent source, means for introducing said solid reagent into said reaction chamber comprising, a

frangible container carrying a measured quantity of said solid reagent, a dispensing device connected to the inlet of said reaction chamber comprising means for normally sealing the inlet to said reaction chamber, a gas lock chamber for receiving said frangible container, means for sealing said gas lock chamber, and means for concurrently severing a portion of said frangible container and establishing a connection between said severed portion, said solvent source and said reaction chamber, said severing means comprising a selectively positionable gating device for establishing a connection between said reaction chamber and said gas lock in one selected position and for establishing a connection between said solvent source and said reaction chamber in another of said selected positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,192,140 McCreary Feb. 27, 1940 2,313,860 Bogue Mar. 16, 1943 2,252,107 Miller et al. May 8, 1951

Claims (1)

1. IN A CHEMICAL REACTION PROCESS REQUIRING THE INTRODUCTION OF SOLID REAGENTS INTO A CLOSED, EVACUATED REACTION SYSTEM HAVING A REACTION CHAMBER AND A SOLVENT SOURCE, MEANS FOR INTRODUCING SAID SOLID REAGENT INTO SAID REACTION CHAMBER COMPRISING A FRANGIBLE CAPILLARY TUBE CONTAINER CARRYING A MEASURED AMOUNT OF SAID SOLID REAGENT, A DISPENSING DEVICE CONNECTED TO THE INLET OF SAID REACTION CHAMBER COMPRISING MEANS FOR NORMALLY SEALING THE IN-

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