Kimyo fanidan laboratoriya mashg’ulotlari

4-tajriba. Тoluoldan benzoy kislota olish

Reaktiv va materiallar: Тoluol — 10 g, kaliy permanganat — 34 g, xlorid kislota.

Хajmi 100 mlli kolbaga 2 g toluol, 60-70 ml suv aralashmasiga oz-ozdan, 6,2 g maydalangan kaliy permanganatni aralashtirib turib qo’shing. Aralashmani 30-40 minut davomida qaynating. Kolba og’ziga sharsimon qaytar sovitgich o’rnatilgan bo’lsin. Qaynash bir meyorda bo’lishi uchun aralashmaga 2-3 dona “qaynatar” tashlab qo’ying. Reaksiya tugagach, permanganatning binafsha rangi marganes (IV)-oksidning qo’ng’ir rangiga aylanadi. Oksid cho’kmaga tushib, aralashma tinsa, suyuqlik rangsiz bo’lib qolishi kerak. Aks holda aralashmaga 3-5 ml spirt yoki 1 g oksalat kislota qo’shib, suyuqlikni yana qizdirib rangsizlantiring. Cho’kmadagi marganes (IV)- oksidni nutch-filtrda filtrlang, cho’kmani ikki marta 10-15 ml iliq suv bilan yuving. Filtratni 30-35 ml eritma qolguncha bug’lating. Хlorid kislota qo’shib, kislotali sharoit yarating (pH-indikator qog’oz). Sovuq filtratdan benzol kislotaning kristallari cho’kmaga tushadi. Uni filtrlang, quriting va torting. Unum nazariy hisoblaganning 70-80% ini tashkil qiladi. Тoza benzoy kislota 120-121^oC da suyuqlanadi.

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