purin

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poluchenie purina iz sekretov i jidkix veshestv purin (imidazo[4,5-d]pirimidin) predstavlyaet soboy kondensirovannuyu bitsiklicheskuyu sistemu, postroennuyu iz pirimidinovogo i imidazolnogo tsiklov. on imeet svoyu, originalnuyu numeratsiyu atomov, kotoraya otlichaetsya ot pravil numeratsii kondensirovannix struktur. purin sushestvuet v vide dvux tautomerov — 9n-purina i 7n-purina. (eshyo dve teoreticheski vozmojnie tautomernie formi, 1n-purin i 3n-purin, ne obnarujeni.) 9n-purin 7n-purin v kristallicheskom sostoyanii purin sushestvuet v vide 7n-tautomera, odnako v rastvore 7n-purin i 9n-purin predstavleni primerno v ravnix kolichestvax. sistema purina, podobno bitsiklicheskoy sisteme indola, soderjit 10--elektronnuyu sistemu. pri etom v imidazolnom koltse elektronnaya plotnost povishena, a v pirimidinovom, naoborot, ponijena po sravneniyu s benzolnim. po kislotnim svoystvam purin (rka = 8.9) — nemnogo bolee silnaya kislota, chem fenol (rka = 9.9), i znachitelno bolee silnaya kislota, chem imidazol (rka = 14.2). takaya sravnitelno visokaya kislotnost obuslovlena znachitelnoy delokalizatsiey otritsatelnogo zaryada aniona mejdu chetirmya atomami azota: osnovnie svoystva purina virajeni slabo (rkb = 11.5); …

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genopurinov protekayut otnositelno legko s takimi nukleofilami, kak amini, tsianidi, alkoksidi, sulfidi i dr. mexanizm reaktsii sn2arom. naprimer: v 9-zameshyonnix galogenopurinax naibolshey reaktsionnoy sposobnostyu obladaet galogen v 8-m polojenii, v 9n-galogenopurinax — galogen v 6-m polojenii. izmenenie reaktsionnoy sposobnosti galogena v polojenii 8 svyazano s obrazovaniem aniona v pyatichlennom tsikle 9n-purina, i nukleofilnaya ataka osushestvlyaetsya po pirimidinovomu koltsu. pri nalichii zamestitelya v 9-m polojenii pyatichlenniy tsikl protoniruetsya rastvoritelem, chto oblegchaet nukleofilnuyu ataku po etomu koltsu. 12.5.3. sposobi polucheniya v sinteticheskom otnoshenii proizvodnie diazinov okazivayutsya bolee dostupnimi, chem sami nezameshyonnie geterotsikli. 1. pirimidinovoe koltso poluchayut kondensatsiey -dikarbonilnix soedineniy s mochevinoy ili eyo proizvodnimi. naprimer, barbiturovaya kislota obrazuetsya iz malonovogo efira i mochevini: barbiturovaya kislota sam pirimidin mojet bit poluchen putyom prevrasheniya barbiturovoy kisloti v trixlorpirimidin, i posleduyushim ego vosstanovleniem: 2. pirazinovoe koltso legko obrazuetsya pri samokondensatsii -aminokarbonilnix soedineniy (v tom chisle-aminokarbonovix kislot — gl. 6.9.2.3). 2,5-digidrotetraalkilpirazini 3. piridazin i ego proizvodnie …

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$ona/c,h50h, 293k n* \ kl ~ nacl | y-ocph3 ntn s n ch n ch; oc>h; cl n* no coh50__ eer: ae ioe h coh30h n -c9h;0° eae: vs coh;0- i; > -cl -c>h;0h lee [3 see ont -2c2hsoh wk, ob fe) hnosch n h rat cl poc, n sl hi n s oo. “hpo; cl xa, | cl -hci, -ih ly | oh o cl me hn hi o\y oh od ‘n h nh) o k’ n=c=0o/h. hn -k* o i nhcnh)> -h,o o f oh hn n, na n poci; a bn “hpo ee 3 o07 sy7 tn ho” sy noi h cl n, + 0+ & 0d ci sy -hcl, -ip sy n h h i? — ti? 3 = bo aoe, i) > “ty oe, “ty q-gp-oh ce ch3 oo n. oo n* cx s + 2 chal / chjoh cx s r sy ‘n - …$

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poluchenie purina iz sekretov i jidkix veshestv purin (imidazo[4,5-d]pirimidin) predstavlyaet soboy kondensirovannuyu bitsiklicheskuyu sistemu, postroennuyu iz pirimidinovogo i imidazolnogo tsiklov. on imeet svoyu, originalnuyu numeratsiyu atomov, kotoraya otlichaetsya ot pravil numeratsii kondensirovannix struktur. purin sushestvuet v vide dvux tautomerov — 9n-purina i 7n-purina. (eshyo dve teoreticheski vozmojnie tautomernie formi, 1n-purin i 3n-purin, ne obnarujeni.) 9n-purin 7n-purin v kristallicheskom sostoyanii purin sushestvuet v vide 7n-tautomera, odnako v rastvore 7n-purin i 9n-purin predstavleni primerno v ravnix kolichestvax. sistema purina, podobno bitsiklicheskoy sisteme indola, soderjit 10--elektronnuyu sistemu. pri etom v imidazolnom koltse elektronnaya plotnost povishena, a...

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