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Сообщения, опубликованные urri

    Пиридинирование имидазола

    в Органическая химия

    Опубликовано

    Не вижу принципиальной разницы. Замешать имидазол в ацетонитриле с гидроксидом натрия,каталитическое количество тетрабутиламмония гидросульфата,а минут через 30-40 добавить алкилирующий агент и вскипятнуть

    Диалкиламид лития и сложный эфир

    в Решение заданий

    Опубликовано

    ДаЧистая правда! Сложные эфиры вполне способны к енолизации,особенно под действием сильных оснований,конденсация Кляйзена тому пример!

    4 часа назад, Artem111 сказал:

    Помогите, пожалуйста, установить структуру продукта реакции. Условия напоминают процесс получения силиловых эфиров енола, но откуда тут берется енол не ясно. На первой стадии должно проходить депротонирование, может ли оно идти по протонам ацетильного фрагмента? Они тут вроде самые кислые. 
    image.png.5846669287a84fd75a1778f0aafe6398.png

    Вот мой вариант ответа. Насколько он близок к правде? image.png.b46608ccec247bc7a4b3c9d2cf096f84.png

     

    Да,так все и будет!

    Странный бисульфит

    в Органическая химия

    Опубликовано

    Это все же метабисульфит,как мне кажется,врочем,неважно,а проблемы могут быть связаны с растворимостью-бисульфитные производные выпадают из более или менее насыщенных растворов бисульфита,а в воде они очень даже неплохо растворяются

    Фенилэтиловый спирт

    в Органическая химия

    Опубликовано

    1. Step 1

      Synthesis of 2-(4-nitrophenyl)ethyl nitrate. To 250 ml of HNO3 at -10 to -5°C under vigorous stirring was added dropwise 61.08 g (0.450 mol) of β-phenethyl alcohol; last few ml of β-phenethyl alcohol was added at 10°C. After the end of the nitration, the reaction mixture was poured with stirring into 3 l of ice-water. After standing the mixture, the dilute acid was decanted from a heavy yellow liquid which was then repeatedly washed with water. Yield of crude nitration products was 102.77 g (96.9%). Nitro compounds were kept at -21°Cto complete crystallization, the crystalline mass was then pressed on a vacuum filter to separate liquid o-isomer. The crystalline substance was then washed twice with ethanol and thoroughly separated by pressing from the residual 2-(2-nitrophenyl)ethyl nitrate which is insoluble in alcohol. After drying in air was obtained 46.26 g of crude 2-(4-nitrophenyl)ethyl nitrate, which was then recrystallized from ethanol. Ethanol was removed under vacuum from the filtrate remaining after the separation of o-isomer, the residue was kept at -21°C for several days and then from the crystallized precipitate was isolated 8.9 g of 2-(4-nitrophenyl)ethyl nitrate. The yield of pure 2-(4-nitrophenyl)ethyl nitrate 37.73 g (35.6%), a needle with a slight greenish-yellow tinge. The total yield of crude product was 55.34 g (52.2%). mp 54-55°C

      Step 2

      Synthesis of 2-(4-aminophenyl)ethanol. To a solution of 1.28 g (0.2048 mol) of 2-(4-nitrophenyl)-ethyl nitrate in 260 ml of methanol was added NiRe prepared from 1.0 g of Ni-Al alloy, then 25 ml of N2H4·H2O was added and the mixture was stirred till exothermic reaction began. When the reaction intensity decreased, to the reaction mixture was added another 25 ml portion of N2H4·H2O, the mixture was heated in a water bath to initiation of a violent reaction. After decomposition of most of the hydrazine, to the mixture was added 17 ml of N2H4·H2O and the reaction mixture was heated at 80°Cuntil the reaction completion and then kept at 40-45°C to complete cessation of gas evolution. Then catalyst was removed from warm solution by filtration, volatiles were distilled off by heating under vacuum in a rotary evaporator. To the liquid residue was added 50 ml of absolute ethanol, the solvent was distilled off and the residual suspension was left for crystallization. The crystals were filtered off from the mother liquor, washed with absolute ethanol and after drying in vacuum over P4O10 was obtained 9.83 g of 2-(4-aminophenyl)ethanol as white crystals. The filtrate was evaporated in a vacuum, the residue was poured onto a petri dish and after the evaporation of volatile components, the substance was rubbed on the filter with a small amount of absolute ethanol. After filtration, the precipitate was washed with absolute ethanol and dried in air. As a result, 5.26 g of a white finely crystalline substance was obtained. Total yield 15.09 g (83%). mp 105°C 1H NMR spectrum, δ, ppm: 2.613, 2.632, 2.650 m (2H, CH2), 3.598, 3.617, 3,635 m (2H, CH2O), 6.593, 6.599, 6.604, 6.615, 6.620, 6.627 (2H, 2,6-Ar), 6.899, 6.906, 6.910, 6.922, 6.926, 6.933 (2H, 3,5-Ar).
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