8-Propiolactone

The carbonylation of COD PdCl2 complex in aqueous sodium acetate produces /rui7x-2-hydroxy-5-cyclooctenecarboxylic acid /i-lactone (240). The lactone is obtained in 79% yield directly by the carbonylation of the COD complex in aqueous sodium acetate solution[220]. /i-Propiolactone (241) is obtained in 72% yield by the reaction of the PdCC complex of ethylene with CO and water in MeCN at —20 " C. /3-Propiolactone synthesis can be carried out with a catalytic amount of PdCC and a stoichiometric amount of CuCl2[221]. 

Indoles can also be alkylated by lactones[l4]. Base-catalysed reactions have been reported for (3-propiolactone[15], y-butyrolactone[10] and 5-valerolac-tone[10]. These reactions probably reflect the thermodynamic instability of the N -acylindole intermediate which would be formed by attack at the carbonyl group relative to reclosure to the lactone. The reversibility of the JV-acylation would permit the thermodynamically favourable N-alkylation to occur. 

Ketene Process. The ketene process based on acetic acid or acetone as the raw material was developed by B. F. Goodrich (81) and Celanese (82). It is no longer used commercially because the intermediate P-propiolactone is suspected to be a carcinogen (83). In addition, it cannot compete with the improved propylene oxidation process (see Ketenes, ketene dimers, and related substances). 

P-Hydroxy acids lose water, especially in the presence of an acid catalyst, to give a,P-unsaturated acids, and frequendy P,y-unsaturated acids. P-Hydroxy acids do not form lactones readily because of the difficulty of four-membered ring formation. The simplest P-lactone, P-propiolactone, can be made from ketene and formaldehyde in the presence of methyl borate but not from P-hydroxypropionic acid. P-Propiolactone [57-57-8] is a usehil intermediate for organic synthesis but caution should be exercised when handling this lactone because it is a known carcinogen. 

Reaction with Lactones. Hydroxycarboxyhc acid ester complexes of titanium are formed by reaction of a tetraalkyl titanate with a lactone, such as P-propiolactone, y-butyrolactone, or valerolactone (35). For example. 

Beta-Propiolactone. p-Propiolactone [57-57-8] was reported to be 4000 times more active than ethylene oxide, and 25 times more... 

Self-condensation of hydroxypivalic acid (also known as 3-hydroxy-a,a-dimethylpropionic acid and as 2-hydroxy-1,1-dimethylpropionic acid) only yields low molecular weight polymers and it is more convenient to prepare the polymer from pivalolactone (also known as a,a-dimethyl-[3-propiolactone) using tributylphosphine as an initiator Figure 25.28). 

Propane suttone beta-Propiolactone Propionaldahyde Propoxur ... 

Propiolactone is subject to attack by enolate ions to give propionic acid derivatives of ketones. It may likewise react with nucleophilic enamines to give carboxyethylation according to the reactions. The morpholide is easily hydrolyzed to the corresponding acid. 

A mixture of 100 g (0.6 mole) of 1-morpholino-l-cyclohexene, 28.8 g (0,4 mole) of /3-propiolactone, and 100 ml of chlorobenzene is placed in a 500-ml round-bottom flask fitted with a condenser (drying tube). The mixture is refluxed for 4 hours. The solvent and excess enamine are removed by distillation at aspirator pressure. (The residue may be distilled to afford the pure morpholide, bp 187-18871 rnm, 1.5090.) Basic hydrolysis may be carried out on the undistilled morpholide. To the crude amide is added 400 ml of 10% sodium hydroxide solution. The mixture is cautiously brought to reflux, and refluxing is continued for 2 hours. The cooled reaction mixture is made acidic (pH 4) and is extracted three times with ether. The combined ether extracts are washed twice with 5 % hydrochloric acid solution and twice with water. The ethereal solution is dried (sodium sulfate), then filtered, and the solvent is removed (rotary evaporator). The residue may be recrystallized from petroleum ether-benzene, mp 64°. 

An alternative route to acrylic esters is via a (3-propiolactone intermediate. The lactone is obtained by the reaction of formaldehyde and ketene, a dehydration product of acetic acid ... 

What is the structure of the polymer produced by treatment of /3-propiolactone with a small amount of hydroxide ion ... 

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