Chlorination propene

Small amounts of pyridine bases increase the corrosion resistance of cement stone without any associated loss of strength [1016]. The use of nitrilo-trimethyl phosphonic acid and an adduct between hexamethylene tetramine and chlorinated propene or butene improves the adhesion to the metal, hardening times, mobility, and strength [ 1770]. The latter adducts are further claimed to be useful as additives in cementing oil and gas wells in salt-bearing strata [1768]. 

The two chlorinated propene compounds shown are colorless liquids with pungent, irritating odors. Allyl chloride is an intermediate in the manufacture of allyl alcohol and other allyl compounds, including pharmaceuticals, insecticides, and thermosetting varnish and plastic resins. Dichloropropene compounds have been used as soil fumigants, as well as solvents for oil, fat, dry cleaning, and metal degreasing. 

The chlorinated propenes are obnoxious compounds. Unlike other compounds discussed so far in this section, their pungent odors and irritating effects lead to an avoidance response in exposed subjects. They are irritants to the eyes, skin, and respiratory tract. Contact with the skin can result in rashes, blisters, and bums. Chronic exposure to allyl chloride is manifested by aching muscles and bones it damages the liver, lungs, and kidney and causes pulmonary edema. 

Allyl chloride is synthesized directly by chlorinating propene under conditions favoring the substitution of hydrogen on the saturated carbon... 

CH3CHCICH2CI. Colourless liquid with a pleasant odour b.p. 96 C, Manufactured by treating liquid chlorine with an excess of liquid propene. It is very similar in properties to ethylene dichloride, and is used for similar purposes. 

In the two examples cited so far the chlorination of propene and the bromination of cyclohexene both criteria are met... 

CH2 CH.CH2.OH mw 58.09 OB to C02 -220.35% colorl, mobile liq with a pungent odor mp —129° bp 96.9°, d 0.8520g/cc at 20/4° RI 1.4127, 1.4133, 1.4135 (Sep values). V sol in w, ethanol and ether. Prepn is by the high temp chlorination of propene, followed by hydrolysis of allyl chloride. Thus,. . Allyl chloride is hydrolyzed at 200psi pressure, 150°C and a pH range of 10—12. Injection of steam forms a water-allyl alcohol azeotrope, which is then treated with diallyl ether to remove water. Final purification by distn leads to a 98% min assay. . (Ref 2). Using procedures such as the above, ... at least two American companies (Shell Chemical Co and Dow Chemical Co) produce a total of several million lbs per year... (Ref 2)... 

It is conceivable that the reaction could be improved if it were run in the presence of a chlorine trap such as propene (cf. Section II.A.3). 

With propene, CH3CH=CH2 (79), there is the possibility of either addition of chlorine to the double bond, or of attack on the CH3 group. It is found that at elevated temperatures, e.g. 450° (Cl then being provided by thermolysis of Cl2), substitution occurs to the total exclusion of addition. This is because the allyl radical (80) obtained by H-abstraction is stabilised by delocalisation, whereas the one (81) obtained on Cl addition is not, and its formation is in any case reversible at elevated temperatures, the equilibrium lying over to the left ... 

Addition of halogen to the double bond takes place when propene reacts with bromine or chlorine at low temperatures. 

Propene undergoes allylic chlorination when propene and chlorine react in the gas... 

Microwave spectroscopic studies of l-fluoro-2-propene show that the cis conformation is more stable than the gauche conformation by approximately 306 cal/mol293 However, when fluorine is replaced by chlorine, bromine, or iodine, the gauche conformation becomes more stable294. These results confirm our expectations that the conformational preferences of allyl halides may depend on a balance of nonbonded attractive effects and a—it interaction effects. 

Chlorination of simple allenes in CH2C12 with or without BF3 afforded a mixture of 2,3-dichloro-l-propene and propargyl chloride [11, 12]. 

The reaction of phenyl-1,2-propadiene with iodine bromide in MeOH afforded a 100% yield of 2-iodo-3-phenyl-3-methoxy-l-propene whereas the reaction in CS2 at 0°C provided a l 4mixture of 2-iodo-3-phenyl-3-bromo-l-propene and l-phenyl-2-iodo-3-bromo-l-propene [16]. The corresponding chlorination shows a lower regios-... 

The best alternative preparation of 3-chloro-2-(chloromethyl)-1-propene involves the direct chlorination of 3-chloro-2-methyl-1-propene using elemental chlorine.4 This method leads to a mixture of products that must be purified by a tedious spinning band distillation, and only yields 34% of the desired product. 

The propene is finally treated with chlorine solution and it undergoes an addition reaction to form the desired product, 1,2-dichloropropane. 

The reaction of chlorine with propene illustrates one difference caused by conjugation. The products of the reaction depend upon the reaction conditions, as illustrated in Figure 4-6. 

At low temperature, propene behaves like another alkene and undergoes a simple addition of a halogen across the double bond to form 1,2-dichlo-ropropane. These conditions minimize the possibility of forming chlorine atoms (chlorine free radicals), and the presence of oxygen traps the few that do form. However, when the conditions promote the formation of chlorine atoms, a substitution occurs to produce 3-chloropropene. 

Dehydration of the tertiary alcohol (6.2.5) is accomplished by chlorination of the tertiary alcohol group by thionyl chloride, forming the diene 2-chloro-9-(3-propen-l-iliden)thioxanthene (6.2.6), the addition to which of dimethylamine at high temperature forms the desired chlorprothixene (6.2.7). 

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