Pentanone 2-

Synonyms diacetone alcohol 2-methyl-2-pentanol-4-one tyranton 4-methyl-2-pentanon-4-ol 

4-Hydroxy-4-methyl-2-pentanone is used as a solvent for nitrocellulose, cellulose acetate, resins, fats, oils, and waxes and in hydraulic fluids and antifreeze solutions. 

Colorless liquid with a faint pleasant odor bp 164 C (327.2 F) freezes at -44°C (-47.2T) density 0.9387 at 20°C (68°F) soluble in water, alcohol, and ether. 

4-Hydroxy-4-methyl-2-pentanone is a mild irritant and a strong narcotic. It can cause irritation in the eyes, nose, throat, and skin. The effect on humans, however, is mild at 100 ppm concentration. 

Animal experiments indicated that it could produce sleep after a period of restlessness and excitement. The symptoms of its toxicity are a marked decrease in breathing and blood pressure, and relaxation of the muscles. Ingestion of this compound in high doses can damage corneal tissue and liver. The oral toxicity in rats was very low, with a LD50 value of 4000 mg/kg. 

---

There also exists an acidregioselective condensation of the aldol type, namely the Mannich reaction (B. Reichert, 1959 H. Hellmann, 1960 see also p. 291f.). The condensation of secondary amines with aldehydes yields Immonium salts, which react with ketones to give 3-amino ketones (=Mannich bases). Ketones with two enolizable CHj-groupings may form 1,5-diamino-3-pentanones, but monosubstitution products can always be obtained in high yield. Unsymmetrical ketones react preferentially at the most highly substituted carbon atom. Sterical hindrance can reverse this regioselectivity. Thermal elimination of amines leads to the a,)3-unsaturated ketone. Another efficient pathway to vinyl ketones starts with the addition of terminal alkynes to immonium salts. On mercury(ll) catalyzed hydration the product is converted to the Mannich base (H. Smith, 1964). 

The cyclization of a-mercaptoketones with ammonium thiocyanate leads to the corresponding 2-mercaptothiazoles (144). For example, 2-mercapto-3-pentanone in ethereal solution with sulfuric acid gives 4-ethyl-5-methyl-2-mercaptothiazole (10), Ri = SH, R2 = Et, R3 = Me, when allowed to stand for 3 hr without heating with ammonium thiocyanate. 

Dehydration of 2 2 3 4 4 pentamethyl 3 pentanol gave two alkenes A and B Ozonolysis of the lower boiling alkene A gave formaldehyde (H2C=0) and 2 2 4 4 tetramethyl 3 pentanone Ozonolysis of B gave formaldehyde and 3 3 4 4 tetramethyl 2 pentanone Identify A and B and suggest an explanation for the formation of B in the dehydration reaction... 

Show how each of the following compounds could be prepared from 3 pentanone In most cases more than one synthetic transformation will be necessary... 

Substitutive nomenclature (Section 4 2) Type of lUPAC nomenclature in which a substance is identified by a name ending in a suffix charactenstic of the type of compound 2 Methylbutanol 3 pentanone and 2 phenylpropanoic acid are examples of substitutive names... 

---