What Is A Rotovap in Organic Chemistry

Rotary evaporator in organic chemistry is a commonly used experimental equipment, which is mainly used to separate liquid solvents from mixtures at low pressure. The equipment utilizes the rotation of the rotary bottle and the heating effect of the heater to make the solvent in the mixture volatilize and condense into liquid through the condenser tube, and finally collect the separated solvent.

The main components of rotovap include rotary bottle, heater, vacuum pump, condenser tube, etc. When the mixture is added into the rotary bottle, the solvent in it can be volatilized and condensed through the condenser tube by adjusting the rotating speed and heating the heater, and finally collected. Different from ordinary distillation, rotary evaporator can evaporate at a lower temperature, thus avoiding the decomposition and loss of some heat-sensitive substances.

Heat-sensitive substances refer to substances that are prone to physical or chemical changes such as decomposition and denaturation at high temperature. These substances may lose their original structure and function in high temperature environment, resulting in quality degradation or adverse effects.

Heat-sensitive substances can be organic compounds, inorganic compounds, polymer materials, etc., including but not limited to biomolecules, protein, drugs, cosmetics, plastics, rubber, etc. The decomposition of heat-sensitive substances is usually caused by the break or recombination of bonds within their molecules.

Several Experiments on Recovery of Organic Chemical Solvents

1. Ether: Firstly, wash the ether waste liquid once with water, then adjust the pH value to neutrality with acid or alkali, then wash it with 0.15% potassium permanganate solution until the purple color does not fade, wash it with 0.15% ~ 1% ammonium ferrous sulfate solution after distilled water, and finally wash it with distilled water for 2 ~ 3 times, discard the water layer, dry it with anhydrous calcium chloride, filter it, and then put it in a lab rotary evaporator for distillation.

2. Petroleum ether: At first, the petroleum ether waste liquid is distilled in a water bath at (81 2)℃ in a rotovap for 15-20min, and the distillate passes through a glass column with an inner diameter of 25mm and a height of 750mm to remove impurities such as aromatic hydrocarbons. The lower layer in the column is filled with silica gel with a height of 600mm, and the upper layer is filled with alumina with a height of 70mm, which is 150mm before use. Repeat the separation in the vacuum rotary evaporator until the blank value (n = 20) and light transmittance (n = 10) are qualified.

3. Chloroform: Chloroform waste liquid is washed with distilled water, concentrated sulfuric acid (1/10 of the amount of chloroform), distilled water and 0.15% hydroxylamine hydrochloride solution in sequence, and then washed twice with re-distilled water, then dehydrated and dried with anhydrous calcium chloride, left for several days, filtered and distilled at a distillation speed of 1-2 drops per second, and distillate with a boiling range of 60-62℃ is collected and stored. For organic impurities that cannot be removed by distillation, activated carbon can be used for adsorption and purification.

4. Carbon tetrachloride: Carbon tetrachloride containing dithizone should be washed once with sulfuric acid and twice with distilled water, and the water layer should be discarded, dried with anhydrous calcium chloride, filtered, distilled in a water bath at 90 ~ 95℃ in a rotary evaporator, and the distillate at 76 ~ 78℃ should be collected; Carbon tetrachloride containing copper reagent should be washed twice with distilled water, dried with anhydrous calcium chloride, filtered and distilled; The carbon tetrachloride containing iodine should be dripped with titanium trioxide until the solution is colorless, then washed twice with distilled water and discarded.

Common Problems and Solutions of Rotovap

1. Q: After the instrument is turned on, the power indicator light does not light up.

A: If the power cord is not connected or wrongly connected, just connect the power cord; If the power switch or circuit board fails, stop using it immediately and contact the manufacturer or professional maintenance personnel.

2. Q: The motor does not turn.

A: If the indicator light of the electric cabinet is on, check whether the internal and external plug connections of the electric cabinet are loose or disconnected, and then plug in the plug again and connect the disconnection. If the indicator light or digital display of the electric cabinet is not on, the fuse should be updated or the power supply should be confirmed to be normal; If the frequency converter is disturbed by high frequency and displays "O.U.", just troubleshoot according to the frequency converter manual.

3. Q: The bath pot is not heated.

A: The green indicator light in the temperature controller is on, but it doesn't heat up. The temperature controller shows "over" or "000", which can be solved by changing the heating ring, solid-state relay or relay board and temperature controller, detecting the wiring of the probe or updating the probe.

4. Q: The test content can't be extracted by vacuum.

A: It is possible that there is solvent in the container and it is limited by the pressure of the saturated ejector, so it is necessary to empty the solvent and try again after the bottle is empty; The capacity of vacuum oil pump decreases, so it is necessary to change oil (water) and clean and repair the vacuum oil pump; The vacuum hose joint is loose, and the vacuum meter leaks, so it is necessary to detect and eliminate the fault section by section along the vacuum pipeline; If there are sundries in the discharge valve and pressure control valve, clean them. The glass wool sandwich panel is damaged, so it can be renewed or repaired.

5. Q: The instrument emits abnormal sound.

A: It is possible that the sealing ring is worn, so just replace it with a new one; It is also possible that the internal gear is worn, the driving part is short of oil, and the motor is out of order. In this case, stop using it immediately and contact us at sales@achievechem.com.

6. Q: The vacuum degree of pressure leakage is not good.

A: It may be that the glass rotating shaft is worn, the sealing ring is worn, the sealing ring is poorly installed, the sealing washer of the decompression gas nozzle is aging, and the vacuum hose is aging. Just update the problem parts.

7. Q: Abnormal lifting.

A: It may be that the circuit board or motor of rotovap is out of order, or the sliding bearing is worn or rusted. In this case, the operator should immediately stop the operation of the instrument and contact professional maintenance personnel.