December 22, 2021 Longchang Chemical

The reason why the ground plug can’t be opened

In the process of organic synthesis reaction, sometimes the grounding instrument sticks together and cannot be disassembled. Improper handling will damage the instrument. Generally, there are three reasons for the failure to open, as follows: 1. Caused by negative pressure: the cause of the solution When the temperature in the volumetric flask is high, cover the ground stopper, cover the ground stopper when the room temperature is high, and open the ground stopper when the room temperature is low. Opening method: slowly heat the volumetric flask (triangular flask) with warm water to generate positive pressure in the bottle. 2. Sticking at the grinding mouth: caused by a liquid with high viscosity: pour the grinding mouth with hot water. Easily crystallized substances cause: pour water on the grinding mouth to dissolve the crystals. The acid burette piston is dry and solid. Use hot water to quickly pour the outside of the piston. Do not heat the piston to the same temperature and open the piston by external expansion. 3. Alkaline substance bonding: Use dilute acid foam to dissolve the alkali. In short, when it cannot be opened, different methods should be adopted according to different reasons.

General method

When the ground piston cannot be opened, it will be crushed if it is screwed hard. You can try the following methods:

(1) Knock one side of the fixed grinding part with a wooden tool, so that the fixed part gradually loosens and separates due to vibration;

(2) Heat the outer layer of the grinding plug, use hot water, electric hair dryer, low fire to bake, and tap it occasionally;

(3) Add a few drops of liquid with strong penetrating power, such as petroleum ether or dilute surfactant solution, to the fixed gap of the grinding mouth. Sometimes it can be opened quickly, but sometimes it takes several days to take effect.

(4) Freeze in the refrigerator, then take out the rubber rod and tap it lightly

Different measures in different situations

  1. Knock Use a wooden tool to gently knock one side of the grinding mouth, so that it will gradually loosen due to vibration. For cemented reagent bottles, ground stoppers of separatory funnels, etc., the stopper and bottle mouth of the instrument can be stuck at the corners of the experimental table or wooden table, and then the wooden utensils can be lighted along the direction at an angle of about 70° to the axis of the instrument. Tap and rotate the instrument intermittently at the same time. Repeated operations like this several times can generally open the grinding mouth that is not severely cemented.
  2. Heating some cemented grinding mouths is inconvenient to knock or knocking is invalid. The outer layer of the cemented part can be heated so that it will be thermally expanded and separated from the inner layer. For example, use a hot damp cloth to “hot compress” the bonding area, use an electric hair dryer or a swimming flame to bake the ground area, and so on.
  3. Infiltration. Some grinding mouths are relatively firm due to chemical erosion, or are expensive instruments with complex structures. They are not suitable for knocking and heating. They can be opened after being soaked in water or dilute hydrochloric acid for several hours. If the instrument is urgently used, organic solvents with strong penetrating power (such as benzene, ethyl acetate, petroleum ether, and dioctyl sodium sulfosuccinate, etc.) can also be added dropwise to the gap between the grinding mouth to make it penetrate and infiltrate to the stick. The fixed parts are thus separated from each other.
  4. Vaseline and other oily substances stick to the piston. You can use a hair dryer or a slight fire to slowly heat it to reduce the viscosity of the oil, or tap the stopper with a wooden stick to open it after melting. (2) The piston will not be stuck due to dust for a long time, so it can be soaked in water, and it can be opened after a few hours.
  5. The piston stuck to the alkaline substance can heat the instrument in water to boiling, and then tap the stopper with a wooden stick to open it.
  6. When the reagent bottle stopper with reagent inside is opened, if the bottle contains corrosive reagents, such as concentrated sulfuric acid, etc., a plastic drum should be placed outside the bottle to prevent the bottle from breaking. The operator should wear a plexiglass mask. Make your face too close to the mouth of the bottle. Open the mouth of toxic vapors (such as liquid bromine) in a fume hood. After the preparations are done, tap the cap with a wooden stick. You can also wash the mouth of the bottle, use the bottle to rinse a little distilled water to moisten the grinding mouth, and then tap the bottle cap lightly.
  7. For bottle stoppers that are stuck due to crystallization or alkali metal salt deposition and strong alkali, the mouth of the bottle can be soaked in water or dilute hydrochloric acid, and it may be opened after a period of time.
  8. Put the stuck piston part in the water-containing cleaning tank of the ultrasonic cleaning machine, and open the piston through the vibration and penetration of the ultrasonic wave. This method works well.
  9. Organic solvent infiltration. Use a dropper to add a small amount of organic solvent (DMF or acetone) to the grinding mouth. When the joint is filled with solvent, try to turn it.
  10. Give it to the glazier, bake it with an acetylene lamp (last trick)

Special cases

  1. For medicines that are not easy to heat, you can add a small amount of distilled water or pure water to the side of the stopper. After the water penetrates into the stopper and the mouth of the bottle, hold the bottle with your hand for a while, and then you can open it
  2. If the bottle contains corrosive reagents, such as concentrated sulfuric acid, a plastic drum should be placed outside the bottle to prevent the bottle from breaking. The operator should wear a plexiglass mask and do not make the face too close to the bottle mouth during operation.
  3. Open the mouth of the toxic vapor bottle to operate in a fume hood. After preparation, you can tap the cap with a wooden stick, or wash the mouth of the bottle. Use the bottle to blow a little distilled water to moisten the ground, and then tap the cap.
  4. When the screw cap cannot be unscrewed, you can use a hair dryer or a small flame to bake around the cap to make it expand by heat, and then use a cloth to wrap the cap to unscrew it forcefully. If the bottle contains non-heatable or flammable substances, you can take a strong rope and tie one end to a fixed object (such as door and window handles), and then loop the rope clockwise on the bottle cap, and then tighten it with one hand On the other end of the rope, hold the bottle with one hand and push it forward to open the bottle cap.

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