Pear odor

Butyl acetate (contributes to characteristic pear odor)... 

Abstract A problem-solving approach to retrosynthesis is introduced. Basic principles for good disconnections are postulated. Examples of interconversion and disconnection of carbinols, alkenes, ketones and nitro compounds are discussed. Concepts of retro-Diels-Alder and re/ro-Wittig disconnections are presented and the mechanisms of reactions explained. Application of the Wittig reaction on the industrial scale is exemphfied by the synthesis of the analog of bombykol, the principal of pear odor and anti-appelizer chlorphentermine. 

Retrosyntheses and syntheses of natural and commercial compounds of medium complexity are presented, such as the analog of the pheromone Bombykol, an unsaturated ester principle of pear odor, a key intermediate in the industrial synthesis of P-carotene, and the anti-appetizer chlorphentermine. 

Example 2.9 Ester with pear odor TM 2.9 is an important product in the food and perfume industries. Complete its retrosynthesis and propose the synthesis. 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless to yellow Odor. Pleasant banana-like mild characteristic banana- or pear- like odor ... 

Cleanup of sample extract. Pipet 2.5 mL of the solution derived from Module GPC into a long-necked round-bottom flask or a pear-shaped flask and add 10 mL of isooctane. By rotating the flask slowly, carefully evaporate the solution to ca 1 mL in a rotary evaporator (water-bath temperature set at 30 0 °C). If an odor of ethyl acetate is still present, add isooctane again and repeat the evaporation. Repeat, if necessary, until no odor of ethyl acetate is present the ethyl acetate must be completely removed. Allow the solution to drain to the upper surface of the column packing and then place a graduated test-tube under the column. 

Clear, colorless liquid with a banana or pear-like odor. Odor threshold concentration is 7 ppm (quoted, Keith and Walters, 1992). A detection odor threshold concentration of 18 pg/m (3.4 ppbv) was determined by Katz and Talbert (1930). 

Clear, colorless, flammable liquid with a pleasant, pear-like odor. Experimentally determined detection and recognition odor threshold concentrations were 200 pg/m (48 ppbv) and 600 pg/m (140 ppbv), respectively (Heilman and Small, 1974). An odor threshold concentration of 240 ppbv was determined by a triangular odor bag method (Nagata and Takeuchi, 1990). Cometto-Muniz and Cain (1991) reported an average nasal pungency threshold concentration of 17,575 ppmv. 

Amyl Acetate,CHj-CH, -CH, -CH, -CH, -COOCH,. Col liq with a pear- or banana-like odor, d... 

PROP Tan flakes, lumps, or pearly leaflets from benzene faint amine-like odor. Mp 93°, flash p 440°F, bp 232° 9 mm. 

Cetyl esters wax occurs as white to off-white, somewhat translucent flakes (typically in the range of 5 pm to several millimeters in the largest dimension), having a crystalline structure and a pearly luster when caked. It has a faint, aromatic odor and a bland, mild taste. 

Properties White, monoclinic, crystalline plates pearly luster faint acetous odor astringent taste. D 1.735, loses 2H20 at 100C, mp 200C (decomposes). Soluble in water and alcohol. 

Hexanedione has a powerful, creamy-sweet, heavy-buttery, oily odor, yet somewhat milder than diacetyl. The odor is often classified as quinone-like . The taste is buttery-cheesy, particularly in acid medium (Arctander, 1967). The flavor is fatty, fruity, pear-like (Chemisis, 1961). 

The odor is often described as resembling that of pear, banana, strawberry, etc. but it may be closer to pear than to any other single fruit (Arctander, 1967). It has a very diffusive, ethereal-fruity, pungent odor, reminiscent of many kinds of ripe and over-ripe fruits, but with a very poor tenacity. An odor threshold of 66ppb was given by Flath et al. (1967). 

It has a pronounced fruity-fresh odor, sweet but slightly nauseating. In dilution it is reminiscent of over-ripe banana and apple (Arctander, 1967). Its excessive concentration produces a fruity, pear character in stinking beans. The flavor is described as flat, earthy, fusel (Chemisis, 1988). 

Colorless, neutral liq pear-like odor and taste. dJJ 0.876. Pure isoamyl acetate bp 142. ng 1.400 the ordinary grade of commerce boils between 120-145. Flash pt, closed cup 92 F (33 C) open cup 100 F (38 C). Sol in 400 parts water miscible with alcohol, ether, ethyl acetate, amyl alco -hoi. Soly of water in isoamyt acetate (25 ) 1.6% by volume. 

Colorless liq aromatic pear-like odor. djf 0.866. bp 179. Slightly sol in water miscible with alcohol, ether. 

Pale yellow or greenish-yellow, globular, elongated or pear-shaped tears slightly balsamic odor and terebene taste. Almost insol in water. Nearly completely sol in alcohol 1 g... 

Isoamyl acetate (EYE-so-A-mil AS-uh-tate) is a clear, colorless liquid with a pleasant fruity odor and taste reminiscent of pears or bananas. When prepared for industrial or commercial use, it is often known as pear oil or banana oil. 

---