شیف باز

[*مینا*]

شیف باز ها که بعد از هگو شیف نامگذاری شده اند گروه فعالی هستند که در درون خود محتوی کربن-نیتروژن با یک پیوند دوگانه که اتم نیتروزن به گروه آریل یا الکیلمتصل شده است اما به اتم هیدروزن نه .فرمول عمومی شیف باز ها بدین صورت است R1R2C=NR3 که گروه R3 یا آلکیل است یا الیل که سبب پایداری شیف باز به عنوان یک ایمین می شود .یک شیف باز مشتقشده از یک آنیلین که R3

اگر یک گروه فنیل یا فنیل جانشینی باشد انرا انیل گویند .شیف باز ها را می توان از گروهایآمینهای اروماتیک و ترکیبات کربونیل با اضافه کردن یک نکلئوفیل فرم همی امینال را به خود میگیرد که با هیدروژنه کردن به ایمین می رسیم .در چنین واکنشی ۴.۴-دی امینو دی فنیل اتر با اورتو وانیلین واکنش می دهد .








Schiff base

From Wikipedia, the free encyclopedia

Jump to: navigation (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FSchiff_base%23column-one), search (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FSchiff_base%23searchInput)http://upload.wikimedia.org/wikipedia/en/thumb/8/8f/Schiffbase.png/150px-Schiffbase.png (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FFile%3ASchiffbase.png)

A Schiff base (or azomethine), named after Hugo Schiff (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FHugo_Schiff), is a functional group (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FFunctional_group) that contains a carbon (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FCarbon)-nitrogen (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FNitrogen) double bond (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FDouble_bond) with the nitrogen atom connected to an aryl (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FAryl) or alkyl (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FAlkyl) group—but not hydrogen (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FHydrogen).[1] (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FSchiff_base%23cite_note-0) Schiff bases are of the general formula R1R2C=N-R3, where R3 is an aryl or alkyl group that makes the Schiff base a stable imine (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FImine). A Schiff base derived from an aniline (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FAniline), where R3 is a phenyl (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FPhenyl) or substituted phenyl, can be called an anil.[2] (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FSchiff_base%23cite_note-1)

Schiff bases can be synthesized from an aromatic (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FAromatic) amine (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FAmine) and a carbonyl (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FCarbonyl) compound by nucleophilic addition (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FNucleophilic_addition) forming a hemiaminal (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FHemiaminal), followed by a dehydration (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FDehydration_reaction) to generate an imine (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FImine). In a typical reaction, 4,4'-diaminodiphenyl ether reacts with o-vanillin (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FVanillin):[3] (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FSchiff_base%23cite_note-2)

http://upload.wikimedia.org/wikipedia/commons/1/19/Schiff_base.gif (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FFile%3ASchiff_base.gif)
A mixture (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FMixture) of 4,4'-diaminodiphenyl ether 1 (1.00 g, 5.00 mmol (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FMmol)) and o-vanillin (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FVanillin) 2 (1.52 g , 10.00 mmol) in methanol (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FMethanol) (40.00 mL) is stirred at room temperature (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FRoom_temperature) for one hour to give an orange precipitate (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FPrecipitate) and after filtration (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FFiltration) and washing with methanol (http://njavan.com/forum/redirector.php?url=http%3A%2F%2Fen.wikipedia.org%2 Fwiki%2FMethanol) to give the pure Schiff base 3 (2.27 g, 97.00%)



منبع :: شیمی دان های دانشکده ی شیمی دانشگاه تبریز