Chlorinated acetaldehydes

Oxygen can be supplied from an air separation plant, as well as from the cost-effective pressure swing adsorption (PSA) process. The Vinnolit oxychlorination process is also able to handle ethylene and/or anhydrous HCI containing vent streams from direct chlorination, acetaldehyde, monochloroacetic acid and other processes. 

Acetaldehyde derivatives chlorinated at the -position are interesting intermediates. Chloroacetaldehyde, CH2C1—CHO, b.p. 85-85.5°/748 mm, can be obtained by chlorinating acetaldehyde in aqueous HC1 at 18-20° 619 or by chlorinating anhydrous acetaldehyde below io° 140a 620 in the latter case there must be efficient cooling, particularly at the start, to avoid inflammation due to reaction of chlorine with the acetaldehyde vapor only a small amount of acetaldehyde is used at first, and the remainder, cooled in Dry Ice, is added later in portions the rate of chlorination (to d 1.31) is controlled by the rate at which the heat of reaction can be removed. 

Light ends are removed by extractive distillation and heavy ends are removed as a side stream from the final acetaldehyde product distillation column. Dissolved gases and methyl and ethyl chlorides are removed in the light ends column and sent to the flare for disposal. Heavy ends consist mainly of crotonaldehyde which is removed as a side stream product. The residue from the bottom of the final distillation column is water containing acetic acid and various chlorinated acetaldehydes. This stream is sent to a biological water treatment unit for disposal. 

The subsequent purification of the product is carried out by a two-step distillation. At first (column k), the light ends, mainly carbon dioxide, methyl, and ethyl chloride, are removed overhead. In the second step (1), acetaldehyde goes overhead water, acetic acid, and some chlorinated products are removed as bottoms and chlorinated acetaldehydes as a side cut. 

When chlorine is passed into boiling ethanol, both chlorination of the methyl group and oxidation of the primary alcohol group to an aldehyde occur, giving trichloro-acetaldehyde or chloral ... 

Acetaldehyde and also many ketones, such as acetone, containing the CH3CO-group behave similarly when treated with bleaching powder, chlorination of the CHsCO - group being immediately followed by fission of the molecule by the alkali present in the bleaching powder ... 

Ammonia, anhydrous Mercury, halogens, hypochlorites, chlorites, chlorine(I) oxide, hydrofluoric acid (anhydrous), hydrogen peroxide, chromium(VI) oxide, nitrogen dioxide, chromyl(VI) chloride, sulflnyl chloride, magnesium perchlorate, peroxodisul-fates, phosphorus pentoxide, acetaldehyde, ethylene oxide, acrolein, gold(III) chloride... 

Iodine Acetaldehyde, acetylene, aluminum, ammonia (aqueous or anhydrous), antimony, bromine pentafluoride, carbides, cesium oxide, chlorine, ethanol, fluorine, formamide, lithium, magnesium, phosphorus, pyridine, silver azide, sulfur trioxide... 

Because of its relatively high, price, there have been continuing efforts to replace acetylene in its major appHcations with cheaper raw materials. Such efforts have been successful, particularly in the United States, where ethylene has displaced acetylene as raw material for acetaldehyde, acetic acid, vinyl acetate, and chlorinated solvents. Only a few percent of U.S. vinyl chloride production is still based on acetylene. Propjiene has replaced acetylene as feed for acrylates and acrylonitrile. Even some recent production of traditional Reppe acetylene chemicals, such as butanediol and butyrolactone, is based on new raw materials. 

Other possible chemical synthesis routes for lactic acid include base-cataly2ed degradation of sugars oxidation of propylene glycol reaction of acetaldehyde, carbon monoxide, and water at elevated temperatures and pressures hydrolysis of chloropropionic acid (prepared by chlorination of propionic acid) nitric acid oxidation of propylene etc. None of these routes has led to a technically and economically viable process (6). 

Another attractive commercial route to MEK is via direct oxidation of / -butenes (34—39) in a reaction analogous to the Wacker-Hoechst process for acetaldehyde production via ethylene oxidation. In the Wacker-Hoechst process the oxidation of olefins is conducted in an aqueous solution containing palladium and copper chlorides. However, unlike acetaldehyde production, / -butene oxidation has not proved commercially successflil because chlorinated butanones and butyraldehyde by-products form which both reduce yields and compHcate product purification, and also because titanium-lined equipment is required to withstand chloride corrosion. 

Enols of simple ketones can be generated in high concentration as metastable species by special techniques. Vinyl alcohol, the enol of acetaldehyde, can be generated by very careful hydrolysis of any of several ortho ester derivatives in which the group RC02 is acetate acid or a chlorinated acetate acid. ... 

Vapor Density (VD) — the mass per unit volume of a given vapor/gas relative to that of air. Thus, acetaldehyde with a vapor density of 1.5 is heavier than air and will accumulate in low spots, while acetylene with a vapor density of 0.9 is lighter than air and will rise and disperse. Heavy vapors present a particular hazard because of the way they accumulate if toxic they may poison workers if nontoxic they may displace air and cause suffocation by oxygen deficiency if flammable, once presented with an ignition source, they represent a fire or explosion hazard. Gases heavier than air include carbon dioxide, chlorine, hydrogen sulfide, and sulfur dioxide. 

Methyl ketones 1, as well as acetaldehyde, are cleaved into a carboxylate anion 2 and a trihalomethane 3 (a haloform) by the Haloform reaction The respective halogen can be chlorine, bromine or iodine. 

In the haloform reaction, methyl ketones (and the only methyl aldehyde, acetaldehyde) are cleaved with halogen and a base. The halogen can be bromine, chlorine, or iodine. What takes place is actually a combination of two reactions. The first is an example of 12-4, in which, under the basic conditions employed, the methyl group is trihalogenated. Then the resulting trihalo ketone is attacked by hydroxide ion ... 

With the growing prominence of the petrochemicals industry this technology was, in turn, replaced by direct air oxidation of naphtha or butane. Both these processes have low selectivities but the naphtha route is still used since it is a valuable source of the co-products, formic and propanoic acid. The Wacker process, which uses ethylene as a feedstock for palladium/copper chloride catalysed synthesis of acetaldehyde, for which it is still widely used (Box 9.1), competed with the direct oxidation routes for a number of years. This process, however, produced undesirable amounts of chlorinated and oxychlorinated by-products, which required separation and disposal. 

The free HCl and Cl generated in the catalytic cycle produce environmentally harmful chlorinated by-products to the extent that more than 3 kg of HCl need to be added to the reactor per tonne of acetaldehyde produced to keep the catalytic cycle going. Modified catalysts such as ones based on palladium/ phosphomolybdovanadates have been suggested as a way of reducing byproduct formation to less than 1% of that of the conventional Wacker process. These catalysts have yet to make an impact on commercial acetic production, however. 

Chlorine-enhancement may offer a partial solution. The addition of the chlorinated olefin TCE, PCE, or TCP to air/contaminant mixtures has recently been demonstrated to increase quantum yields substantially [1, 2, 6]. We recently have extended this achievement [3], to demonstrate TCE-driven high quantmn efficiency conversions at a reference feed concentration of 50 mg contaminant/m air not only for toluene but also for other aromatics such as ethylbenzene and m-xylene, as well as the volatile oxygenates 2-butanone, acetaldehyde, butsraldehyde, 1-butanol, methyl acrylate, methyl-ter-butyl-ether (MTBE), 1,4 dioxane, and an alkane, hexane. Not 1 prospective contaminants respond positively to TCE addition a conventional, mutual competitive inhibition was observed for acetone, methanol, methylene chloride, chloroform, and 1,1,1 trichloroethane, and the benzene rate was altogether unaffected. 

Butyrchloral has been prepared by chlorination of acetaldehyde 2 and of paraldehyde. Butyrchloral hydrate has been prepared by treatment of a,j8-dichlorobutyraldehyde with chlorine and water.3 Butyrchloral has also been prepared4 by treatment of crotonaldehyde with hydrogen chloride followed by chlorination. Brown and Plump have used a procedure similar to the one described here.3... 

Chloroacetaldehyde, production from acetaldehyde, 1 105 Chloroacetamide, l 142 herbicides, 13 303 Chloroacetate esters, 1 142 physical properties of, 1 142t Chloroacetic acid, 1 136-139 end use of chlorine, 6 135t physical properties of, l 137t producers, l 139t... 

Halogens, See also Bromine (Br) Chlorine (Cl) Fluorine (F) Iodine (I) higher aliphatic alcohols, 2 5 in N-halamines, 13 98 reactions with acetaldehyde, 1 105 reactions with acetone, 1 163 reactions with acetylene, 1 180 reactions with alkanolamines from olefin oxides and ammonia, 2 125—126 reactions with aluminum, 2 284—285, 349-359... 

Alkanes n-butene, isopentane, isooctane Cydoalkanes t dohezane, methylcyclopentane Olefins (sometimes called alkenes ) ethylene, propylene, butene Cydoolefins ( clohezene Alkynes acetylene Aromatics toluene, i ene CHLORINATED HYDROCARBONS ALDEHYDES, RCHO formaldehyde, acetaldehyde KETONES, RCX R " acetone, methylethylketone NITRIC OXIDE, NO ... 

Kinetic and thermodynamic parameters have been measured for the chlorination of simple aliphatic and aryl alkyl ketones in strong acid media by chloramine-B (sodium A-chlorobenzenesulfonamide). Catalysis of the monochlorination of acetaldehyde in anhydrous carbon tetrachloride by trichloroacetic acid, and by hydrogen chloride, are reported. IR and UV spectroscopy have been used to probe the reaction of acetaldehyde with trichloroacetic acid in carbon tetrachloride. " Two cyclic 1 1 intermediates have been identified, and are found to be in equilibrium. 

Photolytic. Major products reported from the photooxidation of butane with nitrogen oxides under atmospheric conditions were acetaldehyde, formaldehyde, and 2-butanone. Minor products included peroxyacyl nitrates and methyl, ethyl and propyl nitrates, carbon monoxide, and carbon dioxide. Biacetyl, tert-butyl nitrate, ethanol, and acetone were reported as trace products (Altshuller, 1983 Bufalini et al, 1971). The amount of sec-butyl nitrate formed was about twice that of n-butyl nitrate. 2-Butanone was the major photooxidation product with a yield of 37% (Evmorfopoulos and Glavas, 1998). Irradiation of butane in the presence of chlorine yielded carbon monoxide, carbon dioxide, hydroperoxides, peroxyacid, and other carbonyl compounds (Hanst and Gay, 1983). Nitrous acid vapor and butane in a smog chamber were irradiated with UV light. Major oxidation products identified included 2-butanone, acetaldehyde, and butanal. Minor products included peroxyacetyl nitrate, methyl nitrate, and unidentified compounds (Cox et al., 1981). 

Chemical/Physical. Chlorination of 2-chloroethyl vinyl ether to a-chloroethyl ethyl ether or P-chloroethyl ethyl ether may occur in water treatment facilities. The alpha compound is very unstable in water and decomposes almost as fast as it is formed (Summers, 1955). Although stable in NaOH solutions, in dilute acid solutions hydrolysis yields acetaldehyde and chlorohydrin (Windholz et al., 1983). At pH 7 and 25 °C, the hydrolysis half-life is 175 d (Jones and Wood, 1964). 

Wet oxidation of phenol at elevated pressure and temperature gave the following products acetone, acetaldehyde, formic, acetic, maleic, oxalic, and succinic acids (Keen and Baillod, 1985). Chlorine dioxide reacted with phenol in an aqueous solution forming p-benzoquinone and hypochlorous acid (Wajon et al., 1982). 

Irradiation of toluene in the presence of chlorine yielded benzyl hydroperoxide, benzaldehyde, peroxybenzoic acid, carbon monoxide, carbon dioxide, and other unidentified products (Hanst and Gay, 1983). The photooxidation of toluene in the presence of nitrogen oxides (NO and NO2) yielded small amounts of formaldehyde and traces of acetaldehyde or other low molecular weight carbonyls (Altshuller et al, 1970). Other photooxidation products not previously mentioned include phenol, phthalaldehydes, and benzoyl alcohol (Altshuller, 1983). A carbon dioxide yield of 8.4% was achieved when toluene adsorbed on silica gel was irradiated with light X >290 nm) for 17 h (Freitag et ah, 1985). 

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