METHOD AND DEVICE FOR PURIFYING 1,4-BIS (BROMODIFLUOROMETHYL) BENZENE
A method and a device for purifying 1,4-bis (bromodifluoromethyl) benzene are disclosed. In order to solve the problem of hard to purify and separate 1,4-bis (bromodifluoromethyl) benzene crude products, diphenylmethane that has a higher boiling point and does not interact with 1,4-bis (bromodifluoromethyl) benzene is mixed with the 1,4-bis (bromodifluoromethyl) benzene crude products for evaporation. Afterwards, the purity of the vaporized product is detected and only that reaching an expected purity is collected to obtain high-purity 1,4-bis (bromodifluoromethyl) benzene.
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This is a division of U.S. application Ser. No. 10/898,925, filed Jul. 27, 2004, which claimed Priority from Taiwanese application No. 93113187, filed May 11, 2004, the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of Invention
The invention relates to a purification method and, in particular, to a method for purifying 1,4-bis (bromodifluoromethyl) benzene.
2. Related Art
Low dielectric-constant materials have smaller dielectric constants that can reduce the interference of currents among wires to increase the transmission functions inside integrated circuits (IC). It has become a trend to apply low dielectric-constant materials to various products. The speed of many advanced products can be increased by using low dielectric-constant materials. Products with low interference wires can reduce power consumption and increase the efficiency to dominate the market.
As reported in the U.S. Pat. Nos. 5,268,202, 1,4-bis (bromodifluoromethyl) benzene is one of the low dielectric-constant materials for IC. The compound can be synthesized from 1,4-bis (difluoromethyl) benzene by bromination. After the reaction, the 1,4-bis (bromodifluoromethyl) benzene crude product contains a little yet-dried solvent, reactant 1,4-bis (difluoromethyl) benzene, (1-bromodifluoromethyl 4-difluoromethyl) benzene, and other side products with higher or lower boiling points. However, these impurities have similar polarities as the main product. Therefore, it is hard to use a silica gel column to purify the 1,4-bis (bromodifluoromethyl) benzene.
SUMMARY OF THE INVENTIONA primary objective of the invention is to provide a method for purifying 1,4-bis (bromodifluoromethyl) benzene.
The disclosed method for purifying 1,4-bis (bromodifluoromethyl) benzene includes the steps of: mixing 1,4-bis (bromodifluoromethyl) benzene crude products with diphenylmethane to obtain a mixture; evaporating the mixture to obtain an evaporated product; detecting the purity of the evaporated products in batches; abandoning the evaporated product if the purity is lower than an expected value, thereby collecting those reaching the expected purity.
According to the above purification method, the invention also provides a device for purifying 1,4-bis (bromodifluoromethyl) benzene. The device is comprised of a flask, a heater, a column, and a collecting cup. The column contains a condenser and a dripping device. The heater provides heat to evaporate the mixture of 1,4-bis (bromodifluoromethyl) benzene and diphenylmethane crude products in the flask. The vapor goes through the column connected to the opening of the flask and condensates in the condenser. The distilled liquid flows out via the dripping device into the collecting cup.
The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein:
As shown in
First, solutions resulting from addition of high boiling-point solvent to 1,4-bis (bromodifluoromethyl) benzene crude products, wherein diphenylmethane is used as the solvent in one embodiment, are mixed to obtain their mixture (step 100). The mixture is evaporated under ambient pressure or a reduced pressure, 10 torr being utilized in one embodiment, to obtain evaporated products (step 200). A gas chromatography (GC) is used to detect the purity of the evaporated products in batches (step 300). The evaporated product with purity lower than an expected value is abandoned (step 400). Finally, the evaporated product reaching the expected purity is collected (step 500).
As shown in
In the following, we further explain the principles of purifying 1,4-bis (bromodifluoromethyl) benzene. We use an embodiment to verify the principles.
The disclosed method for purifying 1,4-bis (bromodifluoromethyl) benzene is to evaporate the mixture of 1,4-bis (bromodifluoromethyl) benzene crude products and diphenylmethane. The evaporate product is detected using the GC, and the impurities are separated. The reason of adding diphenylmethane is that its boiling point is higher than that of 1,4-bis (bromodifluoromethyl) benzene. It does not evaporate or interact with 1,4-bis (bromodifluoromethyl) benzene during the evaporation process. Therefore, it is left inside the flask 80 and the column 40 after evaporation. 1,4-bis (bromodifluoromethyl) benzene is pushed out to reduce their residues on the flask 80 and the column 40. One is thus able to obtain high-purity 1,4-bis (bromodifluoromethyl) benzene.
In this embodiment, 1-liter 1,4-bis (bromodifluoromethyl) benzene crude products and 420-ml diphenylmethane are mixed in the round-bottom flask 80. The mixture is evaporated under a pressure of 10 torr. The vapor passes through the column 40 filled with U-shape ceramics. After condensation by the condenser 50, the evaporated liquid flows into the collecting cup 70 via the dripping device 60. Whenever 5 gram of the evaporated liquid is collected, it is detected using the GC (whose column model is Cp-Sil 43 CB). The first 140 grams of evaporated liquid with more impurities are directly tossed away. The rest 1,4-bis (bromodifluoromethyl) benzene can reach a purity of above 99.6%, which is the expectation value of the invention. The evaporation process continues until the residual 1,4-bis (bromodifluoromethyl) benzene contents inside the flask 80 is about 1%, as detected by the GC. Totally, 800 grams of 1,4-bis (bromodifluoromethyl) benzene is collected in this embodiment.
In summary, the invention evaporates the mixture of 1,4-bis (bromodifluoromethyl) benzene crude products and diphenylmethane in order to reduce the residues of 1,4-bis (bromodifluoromethyl) benzene and only collects an evaporated liquid reaching an expected purity. This can separate impurities that are hard to remove from a silica gel column.
Certain variations would be apparent to those skilled in the art, which variations are considered within the spirit and scope of the claimed invention.
Claims
1. A device for purifying 1,4-bis (bromodifluoromethyl) benzene, comprising:
- a flask, which is used to accommodate a mixture of 1,4-bis (bromodifluoromethyl) benzene crude products with diphenylmethane;
- a heater, which provides heat to evaporate the mixture into a vapor;
- a column, which is connected to the opening of the flask and contains a condenser and a dripping device; wherein the condenser condensates the vapor to obtain an evaporate liquid, and the dripping device guides the evaporate liquid to flow out; and
- a collecting cup, which collects the evaporate liquid to obtain an evaporate product.
2. The device for purifying 1,4-bis (bromodifluoromethyl) benzene of claim 1 further comprising a temperature controller and a temperature recorder to control and record the temperature.
3. The device for purifying 1,4-bis (bromodifluoromethyl) benzene of claim 1, wherein the column is filled with Rasching ceramics as the evaporation plate.
Type: Application
Filed: Nov 14, 2008
Publication Date: Mar 12, 2009
Applicant: CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY (Taoyuan County)
Inventors: Shean-Jeng JONG (Longtan Township), Chun-Hsu LIN (Longtan Township), Chao-Chou TU (Longtan Township), Chung-Chien CHANG (Longtan Township)
Application Number: 12/270,919