Abstract:
A reaction vessel support device for mounting on a magnetic stirrer hotplate. The modular device comprises a base unit capable of positioning and seating at the reaction hotplate, and an insert formed non-integrally with the base unit comprising a reaction vessel receiving portion capable of seating and locating about a portion of a reaction vessel. At any one time, the base unit is capable of accommodating a plurality of different shaped and sized inserts each insert being configured to seat and support a specific reaction vessel of particular shape and size. The device therefore serves as a magnetic stirrer hotplate adapter.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a device for positioning at a reaction plate, the device being configured to seat a reaction vessel at the reaction plate. 
     (2) Description of the Related Art 
     Laboratory based chemical reactions are typically carried out in a reaction vessel and where the reaction medium is liquid based, the reaction vessel is typically a round bottomed glass flask, commonly borosilicate, which is sold under the brand name Pyrex® by Corning of Corning, N.Y. 
     In order to drive the reaction heat is supplied to the reaction vessel which in turn transfers the heat to the reaction medium. The common bunsen burner represents one of the more primitive sources of heat used in the laboratory to heat reaction vessels. A further example is the commonly used oil bath in which the oil is heated by heating elements located within the bath. Oil baths have found particular use where elevated temperatures are required. 
     When used within a laboratory environment, the naked flame of the bunsen burner is particularly hazardous as it may serve as an ignition source for flammable solids, liquids or vapour. Oil baths pose a number of significant hazards. Firstly, the viscosity of the oil decreases when heated and spillage or splattering of the heated oil commonly results in skin burns or provides an ignition source. However, one of the more frequent accidents associated with oil baths stems from overheating of the oil resulting in ignition or explosion. 
     Hotplates and hotplate stirrers have been available for sometime and represent significantly safer laboratory heat sources. Hotplate stirrers operate by generating a rotating electromagnetic field in the region of the hotplate which induces a rotation effect on a magnetised stirring bar positioned within the liquid to be stirred. Resistance heating elements positioned in contact with the hotplate provide a means for heating the substantially planar working surface. Heat is supplied from the hotplate either directly to the reaction vessel, in contact with the hotplate, or via a liquid, typically an oil bath, positioned on the hotplate working surface. When used in combination with an oil bath, the significant risks posed to laboratory personnel remerge. Where a liquid/oil bath is not used the limited surface contact area between the planar hotplate and the curved flask provides for inefficient heat transfer and a limited heating effect. 
     One known device includes an adapter block constructed from aluminum or stainless steel for positioning over a stirrer hotplate. The adapter block comprises a plurality of recesses, each recess being configured to seat and partially house a reaction vessel. As a result of the extended surface contact area between the adapter block and reaction vessel, heat generated by the hotplate is efficiently transferred to the reaction medium within the reaction vessel. 
     The known device described above is specifically designed for parallel synthesis involving the simultaneous heating and stirring of multiple reaction vessels positioned outside the perimeter of the hotplate. This known adapter block is specifically designed for use with test tube or boiling tube type reaction vessels having a substantially elongate shape. Additionally, as the reaction vessels are located outside the perimeter of the reaction plate the rotational effect imparted to the magnetised stirring bar within each reaction vessel is reduced. This may be a particular problem where the reaction medium is particularly viscous. 
     BRIEF SUMMARY OF THE INVENTION 
     The inventors provide a reaction vessel support device configured for positioning at a reaction plate, the device being adaptable and configured to receive and support a single or a plurality of reaction vessels of different shapes and dimensions. The device of the present invention is modular, being constructed from separate and interchangeable components. In particular, a base unit capable of positioning at the reaction plate is configured to mate with an insert selected from a set of inserts, each respective insert being configured to seat a different shaped and/or sized reaction vessel. 
     The base unit may comprise a single recessed portion positioned within the base unit so as to be aligned directly over the reaction plate such that the majority of the recessed portion is located within the perimeter of the reaction plate. An insert selected from the range of different inserts is capable of seating within the recessed portion. Effective heat transfer is provided between insert and base unit due to the shape and dimensions of an exterior surface of the insert corresponding to the shape and dimensions of the recessed portion of the base unit. In particular, the distance between the insert and recessed portion, in the region of the recess, may be within the range 0 to 5 mm. 
     As the recess, the insert and hence the reaction vessel are aligned centrally with respect to the heating plate an enhanced heating effect is achieved over similar known devices in which the reaction vessels are positioned off centre. Additionally, effective stirring of the reaction medium is also possible, particularly where viscous liquids are used due to this centralised location of the reaction vessel within the magnetic field generated over the reaction plate. 
     According to a first aspect of the present invention there is provided a reaction vessel support device for positioning at a reaction plate, said device comprising: a base unit capable of positioning in contact with said reaction plate; an insert formed non-integrally with said base unit, said insert comprising at least one reaction vessel receiving portion capable of seating and locating about a portion of a reaction vessel; and a single recessed portion formed in said base unit capable of seating and locating about said insert, said recessed portion positioned at said base unit such that said insert is located substantially centrally relative to said reaction plate. 
     Preferably, the shape and dimensions of a convex surface region of said insert configured for locating within said recessed portion correspond substantially to the shape and dimensions of the concave recessed portion of the base unit. 
     Preferably, a shape of said insert and said recessed portion are configured such that a distance between said recessed portion and said insert, in the region of said recessed portion, is substantially uniform. The distance between the convex surface region of the insert and the surface of the recessed portion may be substantially zero or the insert and base unit may be configured to provide a gap distance of up to 5 mm. 
     Preferably, the recessed portion is dish or bowl shaped being defined by at least one side wall and a base. 
     Preferably, each insert comprises a single reaction vessel receiving portion capable of seating and locating about a portion of a single reaction vessel. Alternatively, each insert may comprise a plurality of reaction vessel receiving portions wherein each insert is capable of seating a plurality of reaction vessels. 
     Each insert and in particular the reaction vessel receiving portion may be designed to seat and locate about a reaction vessel of specific size and shape. Accordingly, via the inserts, the reaction plate adapter of the present invention may be configured to support independently round bottom flasks of sizes of 25 ml, 50 ml, 100 ml, 250 ml, 500 ml, 1 L, 2 L or 3 L. Additionally, the inserts may be configured to receive and support reaction flasks of any shape commonly used within the laboratory environment. The present invention is also configurable for use with sealable high pressure reaction vessels. 
     A lip may be provided at the insert configured for seating at an upper region of the recessed portion whereby the insert may be suspended within the recess by the lip. The lip may be annular or may be discontinuous possibly in the form of radially extending projections. 
     Preferably, the device comprises location means provided at said base unit capable of seating said base unit in position at the reaction plate. The location means is capable of inhibiting lateral displacement of the device relative to the stirrer hotplate. 
     A lower surface of the device may comprise a central cavity corresponding in size and shape to the reaction plate. Accordingly, the reaction plate is configured to locate partially within the cavity so as to ensure the device is effectively located in position. Alternatively, location feet or projections may be provided towards the underside of the base unit for abutting against the reaction plate and releasably locking the device in position. In particular, the location feet or projections may be removeably connected to the base unit, for example being screwed into the underside surface. Accordingly, a user may detach and reattach the location feet at the base unit enabling the device for use with reaction plates of different sizes and shapes. For example, a square reaction plate may require four location feet provided at the underside surface of the base unit whilst three location feet would be sufficient to secure the device in position at a substantially circular reaction plate. 
     Preferably, an underside surface of the base unit comprises means to enable the location feet to be secured at a plurality of different positions on the underside surface such that the location means is adaptable and may be configured specifically by a user to allow the device to be secured to any one of a plurality of different shaped and sized reaction plates. 
     The base unit and insert of the present invention may be made of any chemically resistant material including for example a polymer based compound, a metal, in particular aluminium or a metal alloy, in particular stainless steel. Additionally, the material of the present invention is chosen to provide efficient heat transfer from the reaction plate to the reaction vessel. 
     According to a second aspect of the present invention there is provided a device for positioning at a reaction plate configured to support at least one reaction vessel, said device comprising: a base unit capable of positioning in contact with said reaction plate; an insert formed non-integrally with said base unit, said insert comprising a dish-like configuration having a concave surface region and a convex surface region, wherein said concave region of said insert is capable of seating and locating about a portion of a reaction vessel; and a single recessed portion formed substantially centrally within said base unit capable of seating and locating about said convex portion of said insert. 
     Accordingly, due to the single recessed portion being formed substantially centrally within the base unit, the reaction vessel, when seated at the insert, may be positioned substantially centrally within the perimeter of the upper surface of the reaction plate. 
     According to a third aspect of the present invention there is provided an adapter block device for a stirrer hotplate, said device comprising: a base unit capable of seating on said reaction plate, said base unit comprising an internal bowl-like cavity, formed substantially centrally within said base unit, said cavity comprising side walls and a base; and a dish-like insert comprising at least one concave surface region capable of seating and locating about a portion of a reaction vessel, and a convex surface region configured to mate with said bowl-like cavity of said base unit, wherein said insert is capable of being removeably accommodated within said base unit. 
     The device of the present invention is capable of fitting to a magnetic stirrer, a hotplate or a magnetic stirrer hotplate of the kind typically used in a laboratory environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: 
         FIG. 1  herein is a perspective view of a reaction vessel support device mounted on a magnetic stirrer hotplate according to a specific implementation of the present invention; 
         FIG. 2  herein is a cross sectional perspective view of the device and hotplate of  FIG. 1  herein; 
         FIG. 3  herein is perspective view of the device of  FIG. 1  herein; 
         FIG. 4  herein is a plan view of the device of  FIG. 1  herein; 
         FIG. 5  herein is a cross sectional side elevation view of the device of  FIG. 1  herein; 
         FIG. 6A  is a perspective view of an insert capable of use with the device of  FIG. 1  herein; 
         FIG. 6B  herein is a cross sectional side elevation view of the insert of  FIG. 6A  herein; 
         FIG. 7A  herein is a perspective view an insert capable of use with the device of  FIG. 1  herein; 
         FIG. 7B  herein is a cross sectional side elevation view of the insert of  FIG. 7A  herein; 
         FIG. 8A  herein is a perspective view of an insert capable of use with the device of  FIG. 1  herein; 
         FIG. 8B  herein is a cross sectional side elevation view of the insert of  FIG. 8A  herein; 
         FIG. 9  herein is a graph of the heat transfer performance of the device of the present invention compared with a conventional oil bath; 
         FIG. 10  herein is a perspective view of a further specific implementation of the device of  FIG. 1  herein; 
         FIG. 11  herein is a cross sectional side elevation view of the device of  FIG. 10  herein; 
         FIG. 12A  herein is a perspective view of an insert capable of use with the device of  FIG. 10  herein; and 
         FIG. 12B  herein is a cross sectional side elevation view of the insert of  FIG. 12A  herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description. 
     Within this specification, the term ‘reaction plate’ includes a magnetic stirrer plate; a hotplate and; a magnetic stirrer hotplate typically found within the art and used within a laboratory environment to provide heat or a stirring effect to a reaction medium housed within a reaction vessel. 
     Within this specification, reference to the central positioning of the flask, insert or recessed portion of the base unit relative to the reaction plate includes an alignment of a central point of the flask, insert or recessed portion with a central point of the reaction plate. Additionally, ‘centrally’ includes the relative positioning of the flask, insert or recessed portion within the perimeter of the reaction plate such that the majority of the flask, insert or recessed portion is positioned within the perimeter of the reaction plate. 
       FIG. 1A  herein illustrates a perspective view of the reaction vessel support device according to the specific implementation of the present invention and  FIG. 2  herein illustrates a cross sectional perspective view of the device. 
     Referring to  FIGS. 1 and 2  herein, reaction station  100  comprises a reaction plate  101  comprising a substantially circular upper working surface (not shown). Reaction plate  101  is formed at one end of a neck portion  108  extending from a substantially rectangular upper surface  111  of reaction station  100 . Suitable control means are provided  106 ,  107  allowing a user to adjust the heating effect provided at hotplate  101  and control the extent of the magnetic field generated in the region of the hotplate. 
     The reaction vessel support device comprises a base unit  102  comprising a bowl-like configuration in which a central recessed portion (not shown) accommodates a dish-like insert  103 . A reaction flask  104  is seated within and supported by insert  103  via a concave receiving portion  206  corresponding in shape, dimension and/or curvature to an exterior, lower portion of reaction vessel  207 . 
     Insert  103  comprises an annular lip portion  203  located at an upper region of the concave inner surface  206 . Lip  203  is configured to seat onto an upper portion of the recessed portion of base unit  102  whereby insert  103  may be suspended via lip  203 . According to the specific implementation of the present invention a gap of substantially 2 mm is provided between the outer convex surface region of the dish-like insert and the surface region of the recessed portion provided within base unit  103 . 
     Two handles  105  are provided at base unit  102 , the handles being positioned at opposite sides of the base unit substantially opposed to one another. Each handle comprises a projection (not shown) comprising screw threads configured to mate with corresponding screw threads (not shown) provided within unit  102 . 
     A slim elongate cavity  109  is provided in an upper region of base unit  102  configured to receive and accommodate a portion of a liquid filled thermometer. A similar additional cavity is provided  110  configured to receive and accommodate an electronic temperature probe, being for example a metal-resistance thermometer. 
     Referring to  FIG. 2  herein a magnet  200  is housed within a cavity  202  extending from an underside surface  208  of reaction station  100  to the reaction plate  101 . A spindle  201  connects magnet  200  to a motor (not shown) whereby magnet  200 , positioned directly below reaction plate  101 , is rotatable in the plane of plate  101  so as to generate a magnetic field within the region of reaction station  100 . A magnetised stirrer bar (not shown) accommodated within reaction vessel  104  is caused to rotate in response to the magnetic field. 
     Base unit  102  comprises an annular groove  204  formed within its exterior surface positioned midway between an upper and lower portion. Groove  204  is configured to receive suitable means for locating a heat shield at the exterior surface of base unit  102 . The heat shield is configured to conceal substantially the entire external surface of unit  102  and is preferably manufactured from a thermally insulating material. 
       FIGS. 3 ,  4  and  5  herein illustrate respectively a perspective view, a plan view and a cross sectional side elevation view of the base unit  102  of  FIGS. 1 and 2  herein. 
     Base unit  102  comprises a substantially centrally positioned recessed portion  300  extending inwardly from an upper region towards a lower region to define a bowl-like cavity. With reference to  FIG. 5  herein the recessed portion  300  comprises an annular side wall  500  extending towards the lower region of a base unit to form a cavity base  501 . The internally concave recessed portion  300  borders, at an upper region, the outer surface of the base unit via an annular chamfered section  502 . This upper region and/or chamfered section  502  is configured to seat annular lip  203  ( FIG. 2 ) so as to suspend insert  103  within recessed portion  300 . 
     A further cavity  503  is provided at a lower region of base unit  102 . Cavity  503  comprises a substantially cylindrical configuration being open at one end  506 , at bottom surface  208  of base unit  102 . Cavity  503  is defined by annular wall  504  extending inwardly from base surface  208  towards the substantially circular innermost wall  505  positioned directly underneath recessed portion  300 . Via cavity  503 , base unit  102  is capable of seating at the reaction plate ( FIG. 2 ) whereby lateral movement of base unit  102  is impeded or preferably prevented. Base unit  102  may be displaced from reaction plate  101  by a user grasping handles  105  and lifting the device upwardly in a direction perpendicular to surface  111  of reaction station  100 . 
       FIGS. 6A and 6B  illustrate a perspective view and cross sectional side elevation view of an insert capable of seating within recessed portion  300 . The dish-like insert comprises an internally concave surface region  601 ,  602 ,  603  and an externally convex surface region  604  having a profile corresponding to a segment of a sphere. A portion of the inner, concave region comprises reaction vessel receiving portion  602  capable of seating and locating about a lower portion of a reaction vessel or flask  104 . The curved vessel receiving portion  602  is bordered at its uppermost region  603  by an annular inclined wall  601  tapering outwardly from the concave bowl  602  towards an upper region of the insert. The tapered annular wall  601  terminates at an annular upper surface  605  which defines a portion of annular lip  600 . 
       FIGS. 7A and 7B  herein illustrate a perspective view and cross sectional side elevation view of a slightly modified version of the insert of  FIGS. 6A and 6B  herein. The insert of  FIGS. 7A and 7B  herein is configured for supporting a larger reaction vessel than that of the insert of  FIGS. 6A and 6B  herein. In particular, a radius of curvature of concave reaction vessel receiving portion  702  is greater than region  602  such that a vessel of larger width or diameter may be accommodated within the insert. Similarly,  FIGS. 8A and 8B  herein illustrate a further variation of insert configured to accommodate a larger reaction vessel than the insert of  FIGS. 7A ,  7 B and  6 A,  6 B herein. The radius of curvature of vessel receiving portion  802  is greater than that of the respective receiving portions  702 ,  602 . Additionally, the depth of the vessel receiving portion  802  of the insert of  FIG. 8  herein is greater than that of the insert of  FIGS. 7A ,  7 B and  6 A,  6 B herein. 
     The annular tapered side wall  601 ,  701  allows enhanced visibility of the reaction flask and hence the flask contents when seated within the insert and positioned at the device. 
       FIG. 9  herein illustrates the heating performance of the base unit according to the specific implementation of the present invention comprising an insert configured to seat a 1 litre flask. The heating performance was evaluated using a fuzzy logic temperature controller both in the block and in the flask. The flask was filled with water to half the total flask volume. The water was stirred using an electrical stirring bar and the oil bath was stirred using a cross shaped stirring bar. Temperatures were measured via the fuzzy logic probe and a separate temperature check thermometer as appropriate. A Heidolph oil bath and a Heidolph MR 3001 K stirring hotplate were used. 
     The fuzzy logic probe, positioned within the base unit and the oil bath, was set to 140° C. The internal flask temperature was monitored by the temperature check thermometer. 
     Curve  900  represents the temperature of the water within the flask supported by the present invention; curve  901  represents the temperature of the water within the flask partially submerged within the oil bath; curve  902  represents the temperature of the base unit and; curve  903  represents the temperature of the oil within the oil bath. 
     As illustrated, the reaction vessel support device and the oil bath behave very similarly as confirmed by the change in temperature over time of both the base unit/oil bath and the water in both flasks. Both the device of the present invention and the oil bath brought the water, within the flask, to the boil after approximately 39 minutes. 
       FIGS. 10 and 11  herein illustrate respectively perspective and cross sectional side elevation views of a further specific implementation of the base unit of  FIGS. 1 to 5  herein. The base unit  1000  comprises centralised cavity  1001  being defined by concave wall  1100  and base  1101 . Annular rim  1006  borders the cavity opening and comprises recessed portions  1002 ,  1003  configured to receive a thermometer and temperature probe, respectively. Handle receiving means  1004  are provided through the body of the base unit for receiving handles  105  (not shown) annular groove  1005  extending around the perimeter of the base unit is capable of receiving the heat shield as described with reference to  FIGS. 1 to 4  herein. Cavity  1103  being defined by walls  1104 ,  1105  is capable of locating about hotplate  101  received through open end  1106  as detailed with reference to  FIG. 5  herein. 
       FIGS. 12A and 12B  herein illustrate respectively a perspective view and a cross sectional side elevation view of an insert configured for seating within the base unit of  FIGS. 10 and 11  herein. The insert comprises internally concave surface region  1202  being defined by annular side wall  1203  and base  1204 . Side wall  1203  is bordered at its upper region by outwardly tapering annular side wall  1206  positioned between an upper flat annular surface  1207  and an annular end region  1205  of curved wall  1203 . Lip  1200  is configured for positioning and seating at upper surface  1006  of the base unit. The exterior, convex, bowl-like surface  1208  comprises a curvature configured to correspond to that of the cavity  1001  of base unit  1000 . 
     Annular lip  1200  comprises two cut-out sections  1201  positioned opposed to one another wherein when insert is seated within recessed portion  1001  thermometer receiving means  1002 ,  1003  are not concealed. 
     According to further specific implementations of the present invention cavity  503 ,  1103  may be replaced by a plurality of, in particular three or four, projections extending from lower surface  208 . The projections, distributed around the perimeter of surface  208 , are spaced apart sufficiently such that each projection is configured to grip the perimeter of the hotplate  101  as the base unit is seated at reaction station  100 . 
     Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.