Hydrogen fluoride as catalyst

With Formaldehyde. The sulfuric acid cataly2ed reaction of formaldehyde [50-00-0] with carbon monoxide and water to glycoHc acid [79-14-1] at 473 K and 70 MPa (700 atm) pressure was the first step in an early process to manufacture ethylene glycol [107-21-1]. A patent (58) has described the use of Hquid hydrogen fluoride as catalyst, enabling the reaction to be carried out at 298 K and 7 MPa (70 atm) (eq. 18). 

TPB is produced by the reaction of tetrapropylene (see page 65) with benzene in the presence of aluminum chloride or hydrogen fluoride as catalyst. The reaction conditions for both catalysts differ insignificantly from each other. 

The use of hydrogen fluoride as catalyst is advantageous in many cases. Hydrogen fluoride can be prepared in situ by the addition of water to the reaction mixture. 

Another possibility for the addition of fluorine to phenylacetylenes is fluorination with xenon difluoride in dichloromethane with anhydrous hydrogen fluoride as catalyst to give products... 

CFC s is supposed to deplete the ozone layer. This has led to a stepwise phase out of CFC s and other ozone depleting substances. Last years a number of destruction technologies have been proposed. For example CFC reacts with alcohol to yield carbon monoxide, carbon dioxide, methyl chloride and hydrogen fluoride. As catalyst a metal halide supported on activated carbon [18] is applied. In this way CFC-113 decomposes by reacting with methyl alcohol... 

Albright, L.F. (1966) Modern chemical technology. VI. Alkylation processes using hydrogen fluoride as catalyst. Chem. Eng., 73, 205-210. 

Preparation by Fries rearrangement of 2-naphthyl propionate [7802] using hydrogen fluoride as catalyst [7803]. 

The vapor-phase catalytic replacement of chlorine by fluorine with hydrogen fluoride as the fluorine source has been the subject of a number of patents for the synthesis of Freons or Genetrons This topic has been carefully reviewed in the literature [2, p 97ff] One advantage of using a catalyst with hydrogen fluoride is to allow some degree of selectivity in the displacement of a specific chlorine from... 

Detal [Detergent alkylation] A process for making detergent alkylate, i.e., alkyl aromatic hydrocarbons such as linear alkyl benzenes, as intermediates for the manufacture of detergents, by reacting C10-C13 olefins with benzene in a fixed bed of an acid catalyst. Developed by UOP and CEPSA as a replacement for their Detergent Alkylate process, which uses liquid hydrogen fluoride as the catalyst. Demonstrated in a pilot plant in 1991 and first commercialized in Canada in 1996. Offered by UOP. 

The Jackson laboratory of the du Pont Company soon became interested in the catalytic power of hydrogen fluoride. The results of its work are recorded in three excellent papers. Using acrolein as the alkylating agent and hydrogen fluoride as the catalyst, peri syntheses have been performed (Calcott et al, 32), both those that are catalyzed by sulfuric acid and others that are not. By appropriate condensation, dehydration, and reduction, perylene was obtained from phenanthrene... 

In this chapter reference has been made to a few issued patents but many do not appear in the bibliography. Practically all the issued patents involving the use of hydrogen fluoride as a catalyst are for details of equipment design or operation, and no chemical principles are involved. The number of these patents has now become very large. 

Xenon difluoride reacts with alkyl iodides at room temperature to give organic derivatives of polyvalent iodine. When an excess of iodomcthane (7) is treated with xenon difluoride it produces a stable solution of methyliodine difluoride in quantitative yield, the use of hydrogen fluoride as a catalyst allows a substantial amount of product to be obtained, while isopropyl iodide decomposes under the action of the reagent.16-21... 

The reaction of xenon difluoride with a series of cis- and trans-phenyl substituted alkenes was examined in detail. 1,1-Diphenylethene, l,1-diphenyl-2-fluoroethene and 1.1-diphenyl-propene form vicinal 1,2-difluoro derivatives in 65 95% yield in dichloromethane solution with hydrogen fluoride as the catalyst.29-32 Two possible mechanisms were discussed.33... 

Thionyl fluoride can be prepared by the reaction of thio-nyl chloride with metal fluorides such as zinc(II) fluoride1 and arsenic (III) fluoride,2 and with metal fluorosulfites.3 It is also obtained by the action of hydrogen fluoride upon a mixture of tetrasulfur tetranitride and copper(II) oxide4 and by the reaction of hydrogen fluoride with thionyl chloride in the absence of6 or in the presence of6 antimony(V) fluoride as catalyst. Another method and the simplest on a laboratory scale involves the reaction of antimony(III) fluoride with thionyl chloride in the presence of antimony ) chloride as catalyst.7 This last procedure is described below. 

The first step is set up to produce hydrogen fluoride and the second yields trichlo-romethane (chloroform). Chloroform is then partially fluorinated with hydrogen fluoride to chlorodifluoromethane using antimony fluoride as catalyst in the third step. Finally, in the fourth step, chlorodifluoromethane is subjected to pyrolysis in which it is converted to tetrafluoroethylene. The pyrolysis is a noncatalytic gas-phase process carried out in a flow reactor at atmospheric or subatmospheric pressure and at temperatures 590 to 900°C (1094 to 1652°F) with yields as high as 95%. This last step is often conducted at the manufacturing site for PTFE because of the difficulty of handling the monomer.9... 

The relative location of refinery and acid plant is one of the most important factors in the economic decision between sulfuric acid and anhydrous hydrogen fluoride as a catalyst for alkylation. Besides the distance, other factors such as regeneration of spent acid, energy costs, the nature of the feed and increasingly stringent regulatory constraints play an important role in the selection of alkylation catalyst. Sulfuric acid is selected for alkylation if feed is rich in pentenes or n-butene. HF is selected if the feed is rich in propenes or isobutane. 

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