TRANG CHỦ Sản phẩm Parr Shaker Hydrogenation Apparatus 3921 Shaker Hydrogenation Apparatus

  Reaction Techniques

Materials to be treated in a Parr hydrogenator are sealed in a reaction bottle with a catalyst and connected to a hydrogen reservoir. Air is removed either by evacuating the bottle or by flushing with hydrogen. Pressure is then applied from the reservoir and the bottle is shaken vigorously to initiate the reaction. The bottle can be heated or cooled during this process, if necessary.  After the reaction reaches the desired point, the shaker is stopped, the bottle vented and the product and catalyst are recovered.

Progress of the reaction can be followed by observing the pressure drop in the system. For example, when using a 250 mL charge in a 500 mL bottle and drawing hydrogen from the standard 4-liter tank, the tank pressure will drop approximately 8 psi for each one-tenth mole of hydrogen consumed. The exact relationship between the pressure drop and the amount of hydrogen consumed can be determined by making a calibration run using a weighed amount of a compound whose hydrogen acceptance is known.





  Convenient Valves and Fittings

Each apparatus is equipped with all necessary valves and fittings for admitting hydrogen to the bottle, for evacuating the bottle and for filling the hydrogen tank-all without disturbing the bottle connection. Separate gages show the bottle pressure and the tank pressure at all times. The four-liter gas tank, bottle holder and a sturdy shaker mechanism are arranged in a compact assembly on a steel base for convenient operation on a laboratory bench or in a hood.

The gas connection from the hydrogen tank to the reaction bottle is made with polypropylene tubing that extends directly into the bottle so that no metal parts come in contact with the charge. The tank itself, its valves and pressure gages are made of stainless steel. These parts are well suited for use with hydrogen. All of these valves have stainless stems, PTFE packing and replaceable PCTFE seats to ensure positive, leak-proof control in quantitative procedures. A smaller, one-liter stainless tank (A16CA2) is available for semimicro operations in which small amounts of gas must be measured. The regular valves are easily transferred to this smaller tank.

A six foot pressure hose is furnished with each apparatus for filling the hydrogen tank from a commercial gas cylinder. This can be attached easily to any gas pressure regulator or tank valve system.



Parr Hydrogenators are certified to the electrical code of the Canadian Standards Association (CSA). However 230V heaters are not CSA approved. All models operating on 230V, including their heaters, are approved for CE certification.


3921 Accessories

Extra Bottles and Accessories can be ordered under the following part numbers:




Safety Considerations

Parr shaker type hydrogenators are usually operated in an open laboratory without additional barricades or protective screens, but the operator must realize that additional protection may be necessary if there is any possibility that a reaction may run out of control, or if unexpected bottle breakage would produce a hazardous spill of toxic or flammable materials. Potentially explosive reactions are best handled with the apparatus located behind a suitable barricade or in a pressure test cell.

There must be no gas burners or open flames near a hydrogenation apparatus. The room must be well ventilated and any gas released from the apparatus should be discharged into an explosion proof hood or ventilating duct. Care must also be taken to prevent ignition by a static charge from an insulated object.

The hazards involved in performing pressure reactions in glass bottles is minimized in these reactors by using carefully selected and pressure tested bottles within steel shielding. In spite of these precautions, a bottle will sometimes break below its rated pressure. The user must be constantly aware of this hazard and take whatever additional precautions he considers necessary to protect himself and others from injury in case a bottle should unexpectedly fail.

All catalysts must be handled cautiously because of their highly reactive nature. Although virgin metal catalysts are generally safe themselves, care must be taken when they are brought into contact with organic liquids or combustible vapors in the presence of oxygen because of their ability to promote rapid oxidation. Any catalyst that has been exposed to hydrogen is also potentially hazardous and may ignite spontaneously as it dries. For this reason, used catalysts must always be kept wetted and out of contact with combustible vapors or solids.



3921 Ordering Guide

The 3920 Series Apparatus can be ordered under either of two catalog numbers. Model number 3921 identifies the basic apparatus without a heating mantle or controller. Model 3926 identifies the same apparatus with a heating mantle and a 4833 Automatic Temperature Controller. One 1000 mL and one 2000 mL reaction bottle with appropriate connectors for each size are furnished with each apparatus, along with twelve spare bottle stoppers, and a six foot pressure hose for filling the hydrogen tank.