1. 100 mL 2-neck R.B.F 에 stirring bar (ca. 2.5cm)을 넣고 상단에 drying tube 를 설치한 condenser 와 stopper 로 상단을 막은 dropping funnel 을 R.B.F 에 빠르게 설치한다. 2. Mg powder (1.27 g)와 anhydrous diethyl ether (5 mL)를 빠르게 R.B.F 에 넣는다. 3. Anhydrous diethyl ether (15 mL)와 bromobenzene (5.3 mL)를 50mL Erlenmeyer flask 에서 섞은 후, glass funnel 을 이용하여 dropping funnel 에 빠르게 넣는다. 4. 약하게 가열하면서(variac 약 2-3) dropping funnel 에 있는 solution 의 1/3 을 5 분동안 천천히 떨어뜨린다 (1-2 초에 한 방울). 5. 반응액이 갈색 빛을 띄면 heating mantle 을 제거하고, dropping funnel 에 있는 나머지 solution 을 20 분간 천천히 떨어뜨린다. 6. 30 분간 상온에서 교반한다.
A. Nitration of Acetanilide 1. 50 mL R.B.F에 acetanilide (1.0 g), conc. sulfuric acid (2.50 mL)와 magnetic stir bar (ca. 1.0cm)를 넣고 R.B.F를 stirring plate위에 클램프로 고정한다. 2. R.B.F를 heating mantle에 넣고 약 40℃로 가열하여 고체를 모두 녹인 후, ice-bath에 서 교반 하며 식힌다. 3. [NO2+ 형성반응] conc. sulfuric acid (0.50 mL)와 70% nitric acid (0.50 mL)를 vial에서 넣 고 조심스럽게 혼합한 후 ice bath에서 냉각시킨다. 4. Vial의 용액을 3분 간격으로 약 1/4씩 pipet을 이용하여 천천히 ice-bath에서 교반 중 인 R.B.F에 넣는다. 5. 첨가가 완료되면 ice-bath를 제거하고 상온에서 10분간 교반 한다. 6. R.B.F에 ice water (20 mL)를 첨가한다.
A. Reaction① 50 mL r.b.f.에 stirring bar, 3-sulfolene(3.3 g), maleic anhydride(2.0 g), xylene(4 mL)을넣는다. (고체를 넣을 때는 powder funnel 이용)② r.b.f를 heating mantle에 넣고 알코올 온도계를 꽂는다.③ r.b.f에 water-cooled condenser를 연결하고 drying tube를 꽂는다. (clip으로 고정)Drying tube를 ‘솜 ☞ CaCl2 ☞ 솜’ 순서대로 채운다.④ 30분 동안 heating한다. (약 100 ℃로 서서히 가열-100도 이상에서 적어도 20분 반응해야함!, gentle reflux) ★후드 꼭 내리기★ ▷ reflux 하는 동안 hot gravity filtration 준비 : Erlenmeyer flask(100 mL, 50 mL), glass funnel, fluted filter paper를 oven에 넣기B. Colored impurity 제거와 Hot gravity filtration (p.99-100, p.107)⑤ Reflux 끝난 반응 용액을 상온에서 5분 방치 후, drying tube를 제거하고 water-cooled condenser를 통해 xylene(8 mL)을 더 넣는다.
Photochromism is defined as a reversible transformation of a chemical species induced in one or both directions by absorption of electromagnetic radiation between two forms, A and B, having different absorption spectra. One of the two molecules will inevitably be more stable than the other, resulting in that form of the molecule being favored by thermodynamics. Positive photochromism involves the conversion of a colorless compound A into a colored compound B. An example of positive photochromism is eyeglasses that change into sunglasses when exposed to light (Figure 1). The lenses in these glasses contain a compound that undergoes a positive photochromism process when exposed to UV light.Several classes of organic photochromic compounds have been identified. These include spiropyrans/spiroxazines, diarylethenes, and azo compounds, among others (Figure 2).In today’s experiment, you will prepare an organic dye that has been shown to participate in negative photochromism.
The Suzuki-Miyaura cross-coupling is a palladium-catalyzed carbon-carbon bond forming reaction that is used in the synthesis of many valuable compounds such as pharmaceuticals, polymers, and agrochemicals. In a typical Suzuki-Miyaura coupling reaction, an arylboronic acid is combined (coupled) with an aryl or vinylic halide under basic conditions in the presence of a Pd-based catalyst to form a single bond between two sp2 -hybridized carbon atoms.Cross-coupling is such an important transformation that the scientists who were integral in its development were recognized with the Nobel Prize in chemistry for 2010. Prof. Akira Suzuki shared the prize jointly with Richard Heck and Ei-ichi Negishi. The Heck and Negishi reactions, along with many other "named" Pd-catalyzed coupling reactions (such as the Sonogashira, Stille, Kumada and Buchwald-Hartwig reactions) are used widely in synthetic, pharmaceutical, and industrial chemistry.
In the laboratory experiment, stilbene was synthesized via a Wittig reaction. The Wittig reaction is robust and widely used in industrial and academic research labs. Catalytic methods offer an alternative. An advantage of a catalytic approach is the ability to generate many moles of product for each mole of catalyst and keep waste to a minimum. Stoichiometric (e.g. Wittig) and catalytic (e.g. metathesis) reactions have concomitant benefits and drawbacks. An overarching goal of the two stilbene synthesis experiments is to directly compare and contrast the two approaches.Catalysts for alkene metathesis, particularly ruthenium (Ru)-containing catalysts, have revolutionized synthetic chemistry. These catalysts have impacted pharmaceutical, natural products and polymer chemistry. Y. Chauvin, R. H. Grubbs and R. R. Schrock were jointly awarded the 2005 Nobel Prize in Chemistry for the development of catalytic alkene metathesis reactions.
Background Information:Georg Wittig (1897) was a German chemist who developed new synthetic methods of considerable importance and studied reaction mechanisms. One of his most important achievements is the discovery of the reaction which bears his name, and for which he ear ned the 1979 Nobel Prize in Chemistry together with the American chemist H. G. Brown.In the Wittig reaction, an organic phosphorus compound with a formal double bond between phosphorus and carbon is reacted with a carbonyl compound. The oxygen of the ca rbonyl compound is exchanged for carbon, the product being an alkene. This method of making alkenes has opened up new possibilities, not the least of which are for the synthesis of biologically active substances containing carbon to carbon double bonds. Fo r example, vitamin A and pharmaceuticals of the prostaglandin family have been synthesized industrially using the Wittig reaction.