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Cadiot-Chodkiewicz Coupling

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Appel Reaction

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The chemistry behind falling leaves

The season of falling leaves is a self-preservation strategy for trees. As autumn brings cooler temperatures, reduced sunlight, and less precipitation and soil moisture, trees prepare for winter by cutting nutrients to leaves and using hormones to make them fall. In 1963, scientists first isolated "abscisic acid" in cotton, thinking it sped leaf drop, hence its name. Further studies revealed it as a vital hormone in plant growth and stress response, like keeping seeds dormant and regulating stomata for water balance, especially in drought, salinity, and cold. However, abscisic acid's role in leaf fall is less significant than thought. Actually, "auxin (Indole-3-acetic acid)" and "ethylene" are key regulators in leaf abscission signaling.

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The chemistry behind Chinese lacquer tree

The lacquer tree, from Asia, produces "raw lacquer" with urushiol, a key ingredient for lacquerware. This natural coating forms a protective, heat- and corrosion-resistant film. However, urushiol is a potent allergen, causing severe reactions, especially with longer, unsaturated hydrocarbon chains.

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Yamaguchi Esterigication

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Haloform Reaction

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Horner-Wadsworth Emmons Reaction

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Chemistry behind "Blueprint"

When we plan for the future, we often refer to a "blueprint." This term originates from a photographic process invented by John Herschel in 1842, which relied on the photosensitive properties of iron compounds, specifically ammonium ferric citrate and potassium ferricyanide. Initially, a design was drawn on semi-transparent paper, then placed over white blueprint paper and exposed to sunlight. The blueprint paper, treated with these iron salts, underwent a photoreaction where trivalent iron ions were reduced to divalent ions.

Potassium ferricyanide reacted with the divalent iron to form insoluble Prussian blue, turning the exposed areas blue while the design-shielded areas remained white. After washing off the unexposed chemicals, a stable, clear image copy was produced. This "cyanotype process" could replicate drawings indefinitely, and was used for long-term preservation in engineering and architecture until digital drafting became prevalent. The term "blueprint" has since come to symbolize a plan for the future

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Chemistry behind Dengue

Dengue is a mosquito-borne disease caused by the dengue virus, mainly spread by "Aedes aegypti." Mild cases have a 1% death rate; 80% show no symptoms, while 15% have mild fever, headache, and muscle/joint pain. Avoid NSAIDs like ibuprofen and aspirin, as they can worsen bleeding risks. Seek medical help if bitten by a tiger mosquito and show symptoms like high fever, severe pain, and redness on the skin.

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Wohl-Ziegler Reaction

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Chemistry behind Yogurt

Yogurt, a popular dairy product many enjoy, is made from animal milk fermented by lactic acid bacteria. The fermentation process of yogurt primarily relies on two specific lactobacilli: "Lactobacillus bulgaricus" and "Streptococcus thermophilus". During fermentation, lactose is broken down into lactic acid by the bacteria. As lactic acid accumulates, the pH of the milk decreases, and the acidic environment causes the casein molecules in the milk to denature, shifting from a dissolved state to a coagulated state, forming the characteristic curd structure of yogurt. Historical evidence suggests that yogurt as a food has a history of at least 4,500 years. The earliest yogurt may have been accidentally obtained when nomadic peoples stored milk in sheepskin bags, and the bacteria in the bags naturally fermented the milk. Since lactose is broken down into lactic acid during yogurt production, yogurt is also suitable for people with lactose intolerance.

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The secret behind Diethyl ether

Diethyl ether was an early anesthetic, a colorless, flammable liquid with a sweet, pungent smell. First synthesized by Persian alchemist Jabir ibn Hayyan in the 8th century, its anesthetic effects were unrecognized until later. In 1846, Dr. William Morton publicly demonstrated ether anesthesia in Boston, revolutionizing surgery. Two months later, British surgeon Robert Liston used ether in Europe's first such surgery.

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Bohlmann-Rahtz Pyridine Synthesis

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Happy Mole Day!

Today is a special holiday—Mole Day. Mole Day is an informal holiday that originated among North American chemists, chemistry students, and chemistry enthusiasts. People celebrate this chemistry-specific festival between 6:02 AM and 6:02 PM on October 23rd. A mole is a common unit in chemistry, and one mole of a substance contains several basic particles equal to Avogadro's number. In the American date format, the celebration time of Mole Day is written as 6:02 10/23, which looks very similar to Avogadro's number 6.02×10²³, hence the birth of this holiday. Moreover, the word "mole" in English also refers to a "mole (animal)", so the mole is used as the mascot of the holiday. Many high schools in the United States, South Africa, Australia, Canada, and other places celebrate Mole Day, where various activities related to chemistry or moles are held to stimulate students' interest in chemistry.

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Chemistry behind the striped skunk

The striped skunk, found across North America, uses a stinky spray when threatened. It warns enemies with head shakes and raised tail. If not deterred, it performs an "upside-down spray," targeting foes with a 4-5m range. Its anal glands store 15ml of liquid for 5 powerful bursts. The spray contains (E)-2-Butene-1-thiol, 3-methyl-1-butanethiol, and 2-phenylethanethiol, creating an overwhelming smell.

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Pechmann Condensation

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From 4 to 50,000: The Incredible Scale-Up of Penicillin

Penicillin, the first broad-spectrum antibiotic, changed how we fight infections. Initially, it was scarce, with only 4 units per milliliter. A U.S. team later boosted this to 40 units using corn-steep liquor, but it was still far from enough.The game-changer was a moldy cantaloupe found by Mary, who worked at a U.S. agriculture lab. She was nicknamed "Moldy Mary" for buying moldy foods to find better penicillin strains. The cantaloupe's mold produced 250 units. By 1945, with further improvements, penicillin output reached 50,000 units per milliliter, allowing mass production.