Teflon boiling point

HF is that it attacks glass, so containers must be made of some inert material such as Teflon, a polytet-rafluoroethylene. The data for this nonaqueous solvent are shown in Table 10.4. As expected from the rather high heat of vaporization (which lies between the values for water and liquid ammonia) liquid HF has a liquid range that spans over 100 °C and a relatively high boiling point. 

The solubility of Teflon AF in perfluorinated compounds was presented by Buck and Resnick.Table 6.4 lists several perfluorinated solvents in order of boiling point. The solubility parameters were calculated from the Small group contribution tables using a value of 100 for the group contribution of a CF group. 

In extraction, analyte is dissolved in a solvent that does not necessarily dissolve the entire sample and does not decompose the analyte. In a typical microwave-assisted extraction of pesticides from soil, a mixture of soil plus acetone and hexane is placed in a Teflon-lined bomb (Figures 28-8 and 28-13) and heated by microwaves to 150°C. This temperature is 50° to 100° higher than the boiling points of solvents at atmospheric pressure. Pesticides dissolve, but the soil remains behind. The liquid is then analyzed by chromatography. 

Figure 3.9. In the oven cavity is a carousel (turntable or rotor) that can hold multiple extraction vessels. The carousel rotates 360° during extraction so that multiple samples can be processed simultaneously. The vessels and the caps are constructed of chemically inert and microwave transparent materials such as TFM (tetrafluoromethoxyl polymer) or polyetherimide. The inner liners and cover are made of Teflon PFA (perfluoroalkoxy). The vessels can hold at least 200 psi of pressure. Under elevated pressures, the temperature in the vessel is higher than the solvent s boiling point (see Table 3.11), and this enhances extraction efficiency. However, the high pressure and temperature may pose safety hazards. Moreover, the vessels need to be cooled down and depressurized after extraction.

After the pumps were started, and the liquid flow rate set to the desired value, the cartridge heaters were energized. Onee all the parameters reached steady-state, the values were recorded for 100 s at a sampling rate of 1 Hz. Thereafter, the power to the copper block was increased and a new set of data reeorded. The experiment was stopped when either the surface temperature was above the boiling point or when the temperature at the base of the eopper bloek rose above 350 °C, which could damage the Teflon jacket and the eleetrieal wires. In these experiments, the test fluids used were deionized water and FC-84. 

Acrylic Anhydride Acrylonitrile Allyl Acetate Ally] Methacrylate Aluminum Chloride Ammonia up to ihft boiling point up 10 boiling pi. up to the boiling point ti d fiquid to boiling pt. 0 - DuPont Teflon FEP u u u u... 

Animal Oils Up to the boiling point eenpaWe DuPont Teflon FEP... 

Better yields of carbon black are obtained by improved separation of the combustion function from the carbon-forming function, as is accomplished in the newer furnace black processes. This approach enables gas oil (high boiling point liquid petroleum fractions) or natural gas to be used to produce carbon black. The cooling function from 1,400°C to about 200°C is accomplished by direct water sprays. The product is removed from the gas stream via a combination of cyclone collectors and glass or Teflon fiber bag filters. One tonne of furnace black is obtained from 5,300 to 7, OOOm (1 atm 15.6°C) of natural gas, or 1,400-2,800 L of gas oil corresponding to 50-70% yields. Oil-based furnace black now supplies about 90% of the current carbon black market, although the special features of the product from small-scale processors still contribute some product [4]. 

The boiling points of solvents are reached rapidly, often posing safety problems (e.g. explosions). To solve these problems, the operation has to be carried out in closed vessels (generally made of Teflon, a material transparent to MW and resistant up to 250°C and 80 psi) and using only small amounts of products (roughly 1/10 of the total volume). This of course constitutes a serious limitation (e. g. reduction in MW efficiency as the penetration depth is far below A, scaling up, etc.). 

Using a simple, sealed, microwave transparent apparatus (e.g.. Teflon or glass), it is possible to rapidly increase the temperature of a reaction in common organic solvents up to 100°C above the conventional boiling point of the solvent, which leads to a thousand-fold acceleration of the reaction rate. For example, methanol, which has a boiling point of 65°C, can be rapidly heated to 160°C and a pressure of 17 atmospheres. 

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