Synthesis Of Raspberry Ketone And Its Analogs

Raspberry ketone is a kind of perfume with fruity fragrance and is widely used as a component of edible flavor and cosmetic fragrance and intermediate of medicine. Via Claisen-Schmidt condensation and hydrogenation reaction, raspberry ketone was synthesized by using p-hydroxybenzaldenhyde as the main raw material. Based on the structural theory of aromatic molecule, we synthesized four analogs of raspberry ketone respectively which was characterized by IR, MS and 1H NMR and whose odor was assessed by perfumers to conform their application prospect as perfumes.Research was performed on the synthesis process of raspberry ketone. Via Claisen-Schmidt condensation, p-hydroxybenzaldenhyde and acetone were used to synthesize 4-(4-hydrophenyl)-butan-3-en -2-one. The optimum reaction conditions were obtained by orthogonal experiments. The yield amounted to 88.4%. From 4-(4-hydrophenyl)-butan-3-en -2-one raspberry ketone was synthesized through hydrogenation catalyzed by Pd/C. The reaction conditions were optimized and the yield was 95.0%. The total yield could reach 84.0%. Product achieved the standard of QB1632-96.Based on the mechanism of Claisen-Schmidt condensation catalyzed by alkali or acid and hydrogenation reaction 1-(4-hydrophenyl)- pentan-3-one, 1-(4-methoxyphenyl)-pentan-3-one, 3-methyl-4-(4-hydrophenyl) -butan-3-en -2-one and 3-methyl-4-(4-methoxyphenyl) -butan-2-one were synthesized from p-hydroxybenzaldenhyde and butanone. The reaction condition of each step was optimized.Through Claisen-Schmidt condensation catalyzed by alkali and hydrogenation reaction 1-(4-hydrophenyl)- pentan-3-one was obtained from p-hydroxybenzaldenhyde and butanone and the yield was 67.8%. The odor assessment of 1-(4-hydrophenyl)- pentan-3-one is that it possesses strong and lasting fragrance of berry, bean like raspberry and coumarin and can be used as modifier and fixative of daily chemical essence.Through methylation, Claisen-Schmidt condensation catalyzed by alkali and hydrogenation reaction the yield of 1-(4-methoxyphenyl)-pentan-3-one was 66.2% using p-hydroxybenzaldenhyde as the main raw material. The odor assessment of 1-(4-methoxyphenyl)-pentan-3-one is that it possesses clear and weak fragrance of berry and can be used as modifier of daily chemical essence. Through Claisen-Schmidt condensation catalyzed by acid and hydrogenation reaction 3-methyl-4-(4-hydrophenyl) -butan-3-en -2-one was synthesized from p-hydroxybenzaldenhyde and butanone and the yield was 56.7%. The odor assessment of 3-methyl-4-(4-hydrophenyl) -butan-3-en -2-one is that it possesses light and weak sweet emanative fragrance of berry and can be used as modifier of daily chemical essence.