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Sintesis Obat Pertemuan I Oleh Drs Nahitma Ginting Msi Apt Fakultas Farmasi USU
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Sintesis Obat Definisi ; Analisis retrosintesis melalui pengubahan gugus fungsi (interkonversi gugus fungsi = IGF) atau pembedahan molekul (diskoneksi) untuk mendapatkan molekul target dari zat awal (Starting material) melalui serangkaian tahapan reaksi kimia
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Forward back direction= arah mundur I will improve, I will be = kt keadaan (adjective) To enhance = to inceise = to rise = to promqte = to make better We have keen knowing each other more than 40 years kami telah kenal satun sama lain lebih dari 10 tahun To deffren= to distinguish = beda,goal = tujuan To provide – more commen, lebih biasa, thesis wiriting = menulis tesis thesis wiriting= cara menulis tesis
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Retrosintesis ialah reaksi mundur dengan simbol (Forward back reaktion) Pengubahan gugus fungsi (IGF) ialah mengubah suatu gugus fungsi menjadi gugus fungsi yang lain, misalnya --NO2 fg -NH2 (fg)dengn cara reduksi menggunakan pereaksi logam Zn dan HCl
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A tempetatur at which a solid material start to liquid = titik leleh = melting point
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Diskoneks i ialah pembedahan molekul untuk menghasilkan suatu sinton yang ekivalen dengan suatu pereaksi. Sinton ialah ekivalen suatu pereaksi Pereaksi ialah bahan kimia yang digunakan dalam suatu reaksi Molekul ta rge t ialah zat yang akan disintesis Zat awal ialah bahan baku yang tersedia dialam yang mudah untuk mendapatkannya
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deskoneksi + ekivalen dengan sinton pereaksi
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What will you talk ? Walking out door, Instead of, I wont to end this topic of the many= dari sekian banyak to get used to,do it agein and egain or repeat it agein and again,for the time beeing =pada saat ini
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IGF Zn + HCl - H2O reaksi reduksi
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IGF NaNO2 + HCl H3O+ 1.diazotasi 2.hidrolisis 1. 2.
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IGF Zn + HCl - H2O reaksi reduksi
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diskoneksi sinton pereaksi nitrasi
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Pemisahan/Pemurnian hasil reaksi Pertemuan ke II Misalnya Reaksi Kimia berikut A + B C + D pereaksi produk 1.Bila campuran sisa pereaksi dan hasil reaksi merupakan campura padatan dan cairan, maka pemisahan dapat dilakukan dengan penyaringan, diikuti dengan pencucian dan pengeringan. Contoh pada pembuatan saccharas ferrikus.
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2. Bila campuran sisa pereaksi dan hasil reaksi merupakan campuran cairan-cairan dan tidak bercampur, ada bidang batas maka pemisahan dapat dilakukan dengan menggunakan corong pisah. Contoh pada pembuatan parasetamol khususnya nitrasi benzena.
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3. Bila campuran sisa pereaksi dan hasil reaksi merupakan campuran cairan-cairan yang homogen atau padatan-padatan,tidak ada bidang batas maka kemungkinan dapat dipisahkan dengan salah satu cara berikut.
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3.1. capuran cairan-cairan dengan titik didih yang jauh berbeda dan termo stabil Pemisahan dapat dilakukan dengan destilasi biasa
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3.2. campuran cairan-cairan dengan titik didih yang jauh berbeda dan termo labil Pemisahan dapat dilakukan dengan hampa destilasi atau pengrangan tekanan
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3.3. Campuran cairan-cairan yang dapat dipisahkan dengan destilasi uap yaitu untuk salah satu campuran itu ikut dengan uap air
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3.4.Untuk cairan-cairan yang mempunyai titik didih berdekatan maka mungkin dapat dipisahkan dengan destilasi bertingkat
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4. Untuk campuran yang kelarutannya berbeda dalam suatu pelarut dapat dipisahkan dengan cara penyarian dengan suatu pelarut yang tidak tercapur (solvent extraction)
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5. Untuk campuran yang berbeda kecepatan distribusi dalam suatu pelarut maka dapat dipisahkan dengan kromatogarafi a.l : Kromatografi kolom Kromatogra Kromatografi kertas Kromatografi lapisan tipis Kromatografi gas Kromatografi cair kenerja tinggi. dll
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6. Untuk campuran yang berbeda kecepatan pembentukan kristalnya dapat dipisahkan/dimurnikan dengan kristalisasi
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CRYSTALLIZATION When an organic compound has been prepared it must be purified from the by- products which are formed at the same time. In the case of solid substances crystallization is ordinarily used for this purpose, although with certain compounds purification can be more readily effected by sublimation or distillation, processes which are described below.
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Choice of Solvent The separation of two substances by means of crystallization is based on the fact that they are present in the mixture to be separated into its constituents in different amounts, or on the fact that the two substances possess different solubilities in the liquid used as a solvent.
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When it is desired to purify a substance by crystallization a solvent should be selected, if possible, in which the impurity is readily soluble, and in which the substance sought is more or less difficultly soluble. Purification is effected most easily when the substance to be purified is appreciably soluble in the hot solvent, and much less soluble in it when cold. If the two conditions stated above can be combined—and this is possiblein many cases—purification is readily accomplished.
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When it is desired to purify a substance by crystallization a solvent should be selected, if possible, in which the impurity is readily soluble, and in which the substance sought is more or less difficultly soluble. Purification is effected most easily when the substance to be purified is appreciably soluble in the hot solvent, and much less soluble in it when cold. If the two conditions stated above can be combined—and this is possible in many cases—purification is readily accomplished. The solvents most commonly used in crystallization are water, alcohol, ether, benzene, petroleum ether, ligroin, carbon bisulphide, chloroform, acetone, and glacial acetic acid. In certain cases hydrochloric acid, carbon tetrachloride, ethyl acetate, toluene, and nitrobenzene have been found of particular value as solvents.
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In order to crystallize a compound the solubility of which is not known, preliminary tests should be made with the solvents enumerated above; about 0.1 gram or less of the substance should be used in each test. The solid is placed in a small test-tube, and the solvent is added a drop at a time and the tube is shaken. After the addition of about 1 cc. of the liquid, if the substance has not dissolved, the tube should be heated until the liquid boils. If the substance does not dissolve, more liquid should be added in small quantities until solution occurs. If a very large amount of the liquid is required for solution, or the substance proves insoluble, another solvent must be used. When solution takes place the tube is cooled by running water. If the substance separates, it is redissolved by heating, and the contents set aside to cool slowly, when crystals will probably form.
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If the substance does not separate to a considerable degree when the hot solution is cooled, similar tests should be made with other liquids. If none of the solvents can be used in this way, either the substance must be obtained by spontaneous evaporation, or a mixture of liquids must be used—a method described below. If the compound is to be crystallized by spontaneous evaporation, cold saturated solutions, prepared by dissolving about 0.1 gram or less of the substance in a number of solvents, are poured onto watch-glasses and left to evaporate slowly.
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6. Some substances form solutions from which the first crystals separate with difficulty. In such cases the solution is "seeded" by adding a trace of the solid substance; a piece the size of the bead of a small pin is sufficient. Crystallization of such substances can often be brought about by scratching with a glass rod the side of the vessel containing the solution; the rough surface so formed assists materially in the formation of the first crystal, after which crystallization proceeds readily. The liquid finally selected for the solvent should be one which yields well-formed crystals, and does not evaporate too slowly.
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7. Use of Freezing Mixtures in Crystallization.—It often happens that substances which do not separate from their hot solutions when the latter are cooled with water, crystallize out well when the solutions are allowed to stand for some time in a freezing mixture. For this purpose, a mixture consisting of equal weights of sodium chloride and finely divided ice or snow, is commonly used; with snow, a temperature of -17° is obtained. A mixture of equal weights of crystallized calcium chloride and snow gives the temperature -48°. A convenient freezing mixture is made by covering finely divided ice with commercial concentrated hydrochloric acid.
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8. Preparation of Crystals.—When a satisfactory solvent has been selected, the material to be crystallized is placed in a beaker and covered with the liquid. The mixture is heated to boiling over a free flame or on a steam-bath if the solvent used is inflammable. It is essential to avoid the presence of a free flame when alcohol, benzene, ether, or petroleum ether are used as solvents. The beaker is covered with a watch-glass, and the solvent is added in small portions at a time until the substance to be crystallized has passed into solution. It may happen that a small amount of a difficultly soluble impurity is present; in this case it is not advisable to add enough solvent to dissolve the impurity.
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8. Preparation of Crystals.—When a satisfactory solvent has been selected, the material to be crystallized is placed in a beaker and covered with the liquid. The mixture is heated to boiling over a free flame or on a steam-bath if the solvent used is inflammable. It is essential to avoid the presence of a free flame when alcohol, benzene, ether, or petroleum ether are used as solvents. The beaker is covered with a watch-glass, and the solvent is added in small portions at a time until the substance to be crystallized has passed into solution. It may happen that a small amount of a difficultly soluble impurity is present; in this case it is not advisable to add enough solvent to dissolve the impurity. When the substance to be crystallized has been dissolved, the solution is filtered while hot through a fluted filter-paper into a beaker. Crystallizing dishes should not be used. If the substance crystallizes out during the filtration, either a hot-water funnel can be used, or enough of the solvent can be added to prevent crystallization. In the latter case, and whenever an excess of solvent has been used, it is advisable to concentrate the solution to crystallization after filtration.
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Karakterisasi Hasil Resksi Pertemuan ke III Didasarkan atas sifat : 1. sifat Kimia 2. sifat Fisika 3. sifat Fisikokimia
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Tetapan fisika dapat digunakan Sebagai dasar karakterisasi bila zat yang kita periksa dalam keadaan murni antara lain ; 1. BERAT JENIS 7. …………. 2. TITIK DIDIH 3. TITIK BEKU 4. KEKENTALAN 5. INDEKS BIAS 6. ROTASI OPTIK
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