2- allyl alcohol

Allyl alcohol (2-propen-l-ol, CH2=CHCH2OH, boiling point 96.9°, density 0.8520, flash point 25°C) is the simplest unsaturated alcohol and is a colorless corrosive liquid with a pungent odor. The vapor can cause severe irritation and injury to eyes, nose, throat, and lungs. Allyl alcohol is miscible with water and miscible with many polar organic solvents and aromatic hydrocarbons, but is not miscible with //-hexane. It forms an azeotropic mixture with water and a ternary azeotropic mixture with water and organic solvents. 

There are four processes for industrial production of allyl alcohol. One involves the alkaline hydrolysis of allyl chloride. 

In this process, the amount of allyl chloride, 20 wt % aqueous sodium hydroxide (NaOH) solution, water, and steam are controlled as they are added to the reactor and the hydrolysis is carried out at 150°C, 200 psi (1.4 MPa) and pH 10 to 12. Under these conditions, conversion of allyl chloride is near quantitative (97 to 98 percent), and allyl alcohol is selectively produced in 92 to 93 percent yield. The main by-product is diallyl ether (CH2=CHCH2OCH2CH=CH2). At high alkali concentrations, the amount of by-product, diallyl ether, increases, and at low concentrations, conversion of allyl chloride does not increase. 

A second process has two steps. The first step is oxidation of propylene to acrolein and the second step is reduction of acrolein to allyl alcohol by a hydrogen transfer reaction, using isopropyl alcohol. 

Another process is isomerization of propylene oxide in the presence of a catalyst (lithium phosphate, Li3P04). 

Separation process Propene Octene Allyl Alcohol 2-vinyl naphthalene 

Gas Recycle OK Impractically large gas flows Insufficient volatility Insufficient volatility 

Liquid Recycle OK OK Product thermally unstable Product labiality 

Induced Phase Not the best OK No, product soluble No suitable 

The 195-260° fractions of the distillates are treated with potassium carbonate to salt out the allyl alcohol and to neutralize the little formic acid present. This allyl alcohol is then distilled and the fraction boiling up to about 103° is collected, or if a column is used, up to 98°. In this way, 845 g. of an allyl alcohol are obtained, which by a bromine titration shows a purity of about 68-70 per cent. This is equivalent to 5 70 to 590 g. of pure allyl alcohol (45-47 per cent theory). 

The alcohol may be made practically anhydrous by refluxing with successive portions of fused potassium carbonate until no further action is observed. The carbonate will remain finely divided and will not become sticky when water is absent. A considerable amount of allyl alcohol is lost mechanically during the drying in this way, so that the potassium carbonate which is used here should be employed for the salting out of fresh portions of allyl alcohol in the first part of subsequent preparations. The allyl alcohol thus produced is dry enough for all practical purposes (98-99 per cent) and it is unnecessary to dry with lime or barium oxide as advised in the literature in order to remove all of the water. The allyl alcohol obtained by this process boils at 94-97°- 

Oarke and Taylor have used the following method with success for obtaining a completely anhydrous product. T he 

The reaction between formic acid and glycerol runs very smoothly and without the tendency toward foaming which results when oxalic acid is used. 

The lower fraction which distils up to the point where the thermometer registers 195° contains a considerable amount of formic ac id and in large scale production it would undoubtedly pay to recover it. 

Properties.—Colourless liquid, with a pungent odour b. p. sp. gr. 0-858 at 15 . 

Reaction.—Add bromine water to a little of the allyl alcohol. It is immediately decolouiised, C3H3OH + Br3 = CjH3lii30H. See Appendix., p. 259. 

Propenyl triiodide is probably formed as an intermediate product, though it does not e.vist in the free state. 

Reaction.—Warm a little of the epichlorhydrin with caustic potash solution. It dissolves, forming glycerol. See Appendix p. 260. 

Malic acid is prepared from the juice of the mountain ash berries by precipitation as the calcium salt. 

Ottolenghi AD, Haseman JK, Suggs F Teratogenic effects of aldrin, dieldrin, and endrin in hamsters and mice. Teratology 9 11-16, 1974 

In manufacture of allyl compounds, resins, plasticizers fungicide and herbicide 

Toxicology. Allyl alcohol is a potent lacrima-tor and is an irritant of the mucous membranes and skin. 

In humans, severe eye irritation occurs at 2 5 ppm and irritation of the nose is moderate at 12.5ppm. In workers exposed to a moderate vapor level there was a syndrome of lacrimation, retrobulbar pain, photophobia, and blurring of vision. The symptoms persisted for up to 48 hours. Skin contact with the liquid has a delayed effect, causing aching that begins several hours after contact, followed by the formation of vesicles. Splashes of the liquid in human eyes have caused moderately severe reactions.  

Allyl alcohol was not carcinogenic in limited oral studies in rats and hamsters. It was mutagenic in bacterial assays and in mammalian cells in culture.  

2-Propanol is stored in glass containers or steel drums. Baked phenolic-lined steel tanks are used for storage and shipping. Alnminum containers shonld not be nsed, as isopropanol may react to form alnminnm isopropoxide. 

EPA-listed priority pollutant in solid waste matrices and groundwater) 

Formula C3H5OH MW 58.1 CAS [107-18-6] Structure and functional group CH2=CH-CH2—OH, primary —OH Synonyms 2-propene-l-ol 2-propenol vinyl carbinol 

Allyl alcohol is used to produce glycerol and acrolein and other ally lie componnds. It is also nsed in the manufactnre of military poison gas. The ester derivatives are nsed in resins and plasticizers. 

The toxicity of allyl alcohol is moderately high, affecting primarily the eyes. The other target organs are the skin and respiratory system. Inhalation canses eye irritation and tissne damage. A 25-ppm exposure level is reported to produce a severe eye irritation. It may canse a temporary lacrimatory effect, manifested by photophobia and blnrred vision, for some hours after exposure. Occasional exposnre of a person to allyl alcohol does not indicate chronic or cnmnlative toxicity. Dogterom and associates (1988) investigated the toxicity of allyl alcohol in isolated rat hepatocytes. The toxicity was independent of lipid peroxidation, and acrylate was fonnd to be the toxic metabolite. 

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An example of this t3T)e of reaction which does not produce a byproduct is the production of allyl alcohol from propylene oxide ... 

I 1 temperature and thus also gives allyl alcohol. 

Allyl Chloride. Comparatively poor yields are obtained by the zinc chloride - hydrochloric acid method, but the following procedure, which employs cuprous chloride as a catalyst, gives a yield of over 90 per cent. Place 100 ml. of allyl alcohol (Section 111,140), 150 ml. of concentrated hydrochloric acid and 2 g. of freshly prepared cuprous chloride (Section II,50,i one tenth scale) in a 750 ml. round-bottomed flask equipped with a reflux condenser. Cool the flask in ice and add 50 ml. of concen trated sulphuric acid dropwise through the condenser with frequent shaking of the flask. A little hydrogen chloride may be evolved towards the end of the reaction. Allow the turbid liquid to stand for 30 minutes in order to complete the separation of the allyl chloride. Remove the upper layer, wash it with twice its volume of water, and dry over anhydrous calcium chloride. Distil the allyl chloride passes over at 46-47°. 

Allyl Bromide. Introduce into a 1-litre three-necked flask 250 g. (169 ml.) of 48 per cent, hydrobromic acid and then 75 g. (40-5 ml.) of concentrated sulphuric acid in portions, with shaking Anally add 58 g. (68 ml.) of pure allyl alcohol (Section 111,140). Fit the flask with a separatory funnel, a mechanical stirrer and an efficient condenser (preferably of the double surface type) set for downward distillation connect the flask to the condenser by a wide (6-8 mm.) bent tube. Place 75 g. (40 5 ml.) of concentrated sulphuric acid in the separatory funnel, set the stirrer in motion, and allow the acid to flow slowly into the warm solution. The allyl bromide will distil over (< 30 minutes). Wash the distillate with 5 per cent, sodium carbonate solution, followed by water, dry over anhydrous calcium chloride, and distil from a Claisen flask with a fractionating side arm or through a short column. The yield of allyl bromide, b.p. 69-72°, is 112 g. There is a small high-boiling fraction containing propylene dibromide. 

Allyl Iodide. Use 29 g. (34 ml.) of allyl alcohol and 340 g. (200 ml.) of 57 per cent, hydriodic acid 84 g. of crude iodide are obtained. Upon adding 29 g. (34 ml.) of allyl alcohol to the combined residue in the flask and the aqueous layer and distilling as before, a further 72 g. of crude allyl iodide may be isolated. B.p. 99-101° (mainly 100°). The compound is very sensitive to light the distillation should therefore be conducted in a darkened room and preferably in the presence of a little silver powder. 

Allyl alcohol may be prepared by heating glycerol with formic acid ... 

Treat the combined distiUates of b.p. 195-260° with anhydrous potassium carbonate to neutralise the Uttle formic acid present and to salt out the allyl alcohol. Distil the latter through a fractionating column and collect the fraction of b.p, up to 99° separately this weighs 210 g, and consists of 70 per cent, allyl alcohol. To obtain anli5 dious allyl alcohol, use either of the following procedures —... 

Regioselective epoxidation of allylic and homo-allylic alcohols... 

Diasterocontrolled hydrogenation of allylic alcohols directed by the -OH group... 

Aside of benzene the chemist has a choice in which allyl she can use. Allyl alcohol, allyl bromide or allyl chloride can be used with equal success but allyl alcohol is a nice bonus because it is easier... 

Substituted epoxides are attacked by organocopper reagents at the least hindered carbon atom and form alcohols (C.R. Johnson, 1973A). With a, 9-unsaturated epoxides tram-allylic alcohols are produced selectively by 1,4-addltion (W. Carruthers, 1973 G.H. Posner, 1972). 

Aryl and vinylic bromides and iodides react with the least substituted and most electrophilic carbon atoms of activated olefins, e.g., styrenes, allylic alcohols, a,p-unsaturated esters and nitriles. 

Torgov introduced an important variation of the Michael addition allylic alcohols are used as vinylogous a -synthons and 1,3-dioxo compounds as d -reagents (S.N. Ananchenko, 1962, 1963 H. Smith, 1964 C. Rufer) 1967). Mild reaction conditions have been successful in the addition of ],3-dioxo compounds to vinyl ketones. Potassium fluoride can act as weakly basic, non-nudeophilic catalyst in such Michael additions under essentially non-acidic and non-basic conditions (Y. Kitabara, 1964). 

Hydrogenation of olefins, enols, or enamines with chiral tVilkinson type catalysts, e.g., Noyort hydrogenation. Hydroboration of olefins with chiral boranes. Sharpless epoxi-dation of allylic alcohols. 

J.-L. Luche, 1978) to give allylic alcohols. L1AIH4 itself tends to reduce the C = C double bond. 

The first practical method for asymmetric epoxidation of primary and secondary allylic alcohols was developed by K.B. Sharpless in 1980 (T. Katsuki, 1980 K.B. Sharpless, 1983 A, B, 1986 see also D. Hoppe, 1982). Tartaric esters, e.g., DET and DIPT" ( = diethyl and diisopropyl ( + )- or (— )-tartrates), are applied as chiral auxiliaries, titanium tetrakis(2-pro-panolate) as a catalyst and tert-butyl hydroperoxide (= TBHP, Bu OOH) as the oxidant. If the reaction mixture is kept absolutely dry, catalytic amounts of the dialkyl tartrate-titanium(IV) complex are suflicient, which largely facilitates work-up procedures (Y. Gao, 1987). Depending on the tartrate enantiomer used, either one of the 2,3-epoxy alcohols may be obtained with high enantioselectivity. The titanium probably binds to the diol grouping of one tartrate molecule and to the hydroxy groups of the bulky hydroperoxide and of the allylic alcohol... 

The catalyst is sensitive to pre-existing chirality in the substrate the expoxidation of racemic secondary allylic alcohols often proceeds tepidly with only one of the enantiomers ... 

Sharpless epoxidations can also be used to separate enantiomers of chiral allylic alcohols by kinetic resolution (V.S. Martin, 1981 K.B. Sharpless, 1983 B). In this procedure the epoxidation of the allylic alcohol is stopped at 50% conversion, and the desired alcohol is either enriched in the epoxide fraction or in the non-reacted allylic alcohol fraction. Examples are given in section 4.8.3. 

A catalytic enantio- and diastereoselective dihydroxylation procedure without the assistance of a directing functional group (like the allylic alcohol group in the Sharpless epox-idation) has also been developed by K.B. Sharpless (E.N. Jacobsen, 1988 H.-L. Kwong, 1990 B.M. Kim, 1990 H. Waldmann, 1992). It uses osmium tetroxide as a catalytic oxidant (as little as 20 ppm to date) and two readily available cinchona alkaloid diastereomeis, namely the 4-chlorobenzoate esters or bulky aryl ethers of dihydroquinine and dihydroquinidine (cf. p. 290% as stereosteering reagents (structures of the Os complexes see R.M. Pearlstein, 1990). The transformation lacks the high asymmetric inductions of the Sharpless epoxidation, but it is broadly applicable and insensitive to air and water. Further improvements are to be expected. 

In all cases examined the ( )-isomers of the allylic alcohols reacted satisfactorily in the asymmetric epoxidation step, whereas the epoxidations of the (Z)-isomers were intolerably slow or nonstereoselective. The eryfhro-isomers obtained from the ( )-allylic alcohols may, however, be epimerized in 95% yield to the more stable tlireo-isomers by treatment of the acetonides with potassium carbonate (6a). The competitive -elimination is suppressed by the acetonide protecting group because it maintains orthogonality between the enolate 7i-system and the 8-alkoxy group (cf the Baldwin rules, p. 316). 

A) Sn2 substitution at the allylic alcohol with hydrobromic acid followed by reaction with the requisite secondary amine, or... 

B) palladium(0)-catalyzed direct amination of the O-acetylated allylic alcohol. 

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