Pirimidina: Perbedaan antara revisi
Konten dihapus Konten ditambahkan
JohnThorne (bicara | kontrib) Tidak ada ringkasan suntingan |
JohnThorne (bicara | kontrib) Tidak ada ringkasan suntingan |
||
Baris 139:
Pyrimidine is also found in meteorites, but scientists still do not know its origin. Pyrimidine also photolytically decomposes into [[uracil]] under UV light.<ref name="pmid19778279">{{cite journal |author=Nuevo M, Milam SN, Sandford SA, Elsila JE, Dworkin JP |title=Formation of uracil from the ultraviolet photo-irradiation of pyrimidine in pure H<sub>2</sub>O ices |journal=Astrobiology |volume=9 |issue=7 |pages=683–695 |year=2009 |pmid=19778279 |doi=10.1089/ast.2008.0324|bibcode = 2009AsBio...9..683N }}</ref>
-->
==
<!--
As a class, pyrimidines are typically synthesized by the “Principal Synthesis” involving cyclization of beta-dicarbonyl compounds with N-C-N compounds. Reaction of the former with amidines to give 2-substituted pyrimidines, with urea to give 2-pyrimidiones, and guanidines to give 2-aminopyrimidines are typical.<ref name="BrownPyrimidines1994p149">{{cite book |author=Brown, D. J.; Evans, R.F.; Cowden, W. B.; Fenn, M. D. |title=The Pyrimidines |publisher=John Wiley & Sons |location=New York |year=1994 |pages=149–239 |isbn=0-471-50656-7|url= |accessdate=}}</ref>
Baris 148:
A novel method is by reaction of certain [[amide]]s with [[carbonitrile]]s under electrophilic activation of the amide with 2-chloro-pyridine and [[trifluoromethanesulfonic anhydride]]:<ref>''Single-Step Synthesis of Pyrimidine Derivatives'' Mohammad Movassaghi and Matthew D. Hill [[J. Am. Chem. Soc.]]; '''2006'''; 128(44) pp 14254–14255; (Communication) {{DOI|10.1021/ja066405m}}</ref>
-->
:[[Image:PyrimidineSynthAmideCarbonitrile.png|400px|
==Reaksi ==
▲:[[Image:PyrimidineSynthAmideCarbonitrile.png|400px|Pyrimidine Synthesis Movassaghi 2006]]
Karena menurunnya kadar basa dibandingkan piridina, substitusi elektrofilik pirimidina kurang lancar. [[Protonasi]] atau [[alkilasi]] biasanya berlangsung pada hanya satu atom nitrogen dalam cincin. [[Oksidasi-N]] mono terjadi melalui reaksi dengan perasida.<ref name="JouleMills5thp253">{{cite book | title=Heterocyclic Chemistry |edition=5th |editor1-last=Joule |editor1-first=John A. |editor2-last=Mills |editor2-first=Keith |publisher=Wiley |location=Oxford |year=2010 |pages=253–4 |quote= |isbn=978-1-405-13300-5 |oclc= |doi= |url= |accessdate=}}</ref>
<!--
Nucleophilic C-substitution should be facilitated at the 2-, 4-, and 6-positions but there are only a few examples. Amination and hydroxylation has been observed for substituted pyrimidines. Reactions with Grignard or alkyllithium reagents yield 4-alkyl- or 4-aryl pyrimidine after aromatization.<ref name="BrownPyrimidines1994p14">{{cite book |author=Brown, D. J.; Evans, R.F.; Cowden, W. B.; Fenn, M. D. |title=The Pyrimidines |publisher=John Wiley & Sons |location=New York |year=1994 |pages=14–15 |isbn=0-471-50656-7|url= |accessdate=}}</ref>
| |||