Teflon sleeved joints

A hydrolysis unit is constructed using the commercially available glassware shown in Figure 2. The collection funnel should be calibrated and marked for volumes of 35 and 85 mL. All 20/40-glass joints of the hydrolysis unit should be assembled with Teflon sleeves and secured with spring clamps to prevent loss of the volatile EMA and HEMA analytes. 

Teflon sleeves are used to assure the vacuum tight connection between the ground joints subjected to heat. The checkers used clear-seal joints in all of the glass connections. 

Ground glass joints were connected using Teflon sleeves or a chlorofluorocarbon stopcock grease. 

Figure 7.12. Apparatus for extracting organic solutes from water. (A) 5-liter reservoir, (B) glass wool plugs, (C) 24/40 ground glass joint with Teflon sleeve,...

Teflon sleeves are useful to keep the joints from freezing. 

There is one other substitute for stopcock grease on standard taper joints the Teflon sleeve. These sleeves are like socks for your joints. Because they are made of Teflon, they are not attacked by solvents, alkalines, and most other chemicals. Thus, they are wonderful for items like solvent flasks which are under constant fume or chemical contact. However, they are not capable of maintaining a static vacuum and should not be used for vacuum work. Thin Teflon sleeves are less expensive, but cannot take physical abuse. Heavier Teflon sleeves have a greater initial cost, but can be used over and over. 

Quickfit joints on reaction flasks should be lined with Teflon sleeves. This is especially important when fine metal dispersions are used, which may otherwise seep through the joints and cause a potential fire hazard. 

The still pot is usually attached to the column by a standard taper joint. Leakage often occurs at this point after the grease has been softened by the heated vapors. This may be avoided by the use of Teflon sleeves instead of grease. For prolonged distillations, such as... 

In a 500 mL round-bottomed flask are placed molybdenum pentachloride (65 g, 238 mmol), anhydrous aluminum chloride (140 g, 1.05 mol), and aluminum powder (8.5 g, 315 mmol), and the mixture is mixed well. To the mixture, benzene (250 mL) is added slowly over a period of ca 15 min. If the temperature of the contents increases too much on addition of benzene, the flask should be cooled by an ice bath. After the reaction mixture has cooled to room temperature, the flask is shaken well to mix the contents and a reflux condenser is attached. A Teflon sleeve should be put on the flask joint to prevent it from freezing and the condenser should be tightly wired to the neck of the flask. The nitrogen pressure is adjusted as 15-17 psi using mercury bubbler. The flask is immersed in the oil bath and the temperature of the bath is raised gradually to 120 °C. After refluxing for 12 h, the mixture is cooled to room temperature and the flask is shaken to mix the contents well. Then the flask is heated again under reflux for 12 h. After the flask has cooled to room temperature, the benzene layer is removed by... 

Continuing to exclude all air and water, the residue is loaded into a Soxhlet extractor. All joints are fitted with Teflon sleeves. The residue is extracted with pentane (150 mL) for 2 days or until the residue becomes white and the solution is reddish brown. The volatiles are removed from the solution to afford the product as a brown solid in 66% yield (3.2 g). mp 80-82°C. 

A different approach for ground joints is the use of Teflon sleeves. This gives the joints a tight fit and does not allow them to seize. The French firm Gachot supply... 

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