Pyrimidine


Pyrimidine

chembox
ImageFile=Pyrimidine chemical structure.pngImageSize=368px
IUPACName=pyrimidine
OtherNames=
Section1= Chembox Identifiers
CASNo=289-95-2
PubChem=9260
SMILES=C1=CN=CN=C1
MeSHName=pyrimidine

Section2= Chembox Properties
Formula=C4H4N2
MolarMass=80.088
Appearance=
Density=
MeltingPt=20–22 °C
BoilingPt=123–124 °C
Solubility=

Section3= Chembox Hazards
MainHazards=
FlashPt=
Autoignition=

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring. [Heterocyclic Chemistry (3rd Edition) Thomas. L. Gilchrist ISBN 0-582-27843-0 ] It is isomeric with two other forms of diazine.

Nucleotides

Three nucleobases found in nucleic acids (cytosine, thymine, and
uracil) are pyrimidine derivatives:

In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively.

In RNA, the complement of A is U instead of T and the pairs that form are adenine:uracil and guanine:cytosine.

These hydrogen bonding modes are for classical Watson-Crick base pairing. Other hydrogen bonding modes ("wobble pairings") are available in both DNA and RNA, although the additional 2'-hydroxyl group of RNA expands the configurations through which RNA can form hydrogen bonds.Fact|date=February 2007

Chemical properties

A pyrimidine has many properties in common with pyridine, as the number of nitrogen atoms in the ring increases the ring pi electrons become less energetic and electrophilic aromatic substitution gets more difficult while nucleophilic aromatic substitution gets easier. An example of the last reaction type is the displacement of the amino group in 2-aminopyrimidine by chlorine [Organic Syntheses, Coll. Vol. 4, p.182 (1963); Vol. 35, p.34 (1955) [http://www.orgsynth.org/orgsyn/pdfs/CV4P0182.pdf Link] ] and its reverse. [Organic Syntheses, Coll. Vol. 4, p.336 (1963); Vol. 35, p.58 (1955) [http://www.orgsynth.org/orgsyn/pdfs/CV4P0336.pdf Link] ] Reduction in resonance stabilization of pyrimidines may lead to addition and ring cleavage reactions rather than substitutions. One such manifestation is observed in the Dimroth rearrangement.

Compared to pyridine, N-alkylation and N-oxidation is more difficult, and pyrimidines are also less basic: The pKa value for protonated pyrimidine is 1.23 compared to 5.30 for pyridine.

Organic synthesis

Pyrimidines can also be prepared in the laboratory by organic synthesis. One method is the classic Biginelli reaction. Many other methods rely on condensation of carbonyls with amines for instance the synthesis of 2-Thio-6-methyluracil from thiourea and ethyl acetoacetate [Organic Syntheses, Coll. Vol. 4, p.638 (1963); Vol. 35, p.80 (1955) [http://www.orgsynth.org/orgsyn/pdfs/CV4P0638.pdf Link] ] or the synthesis of 4-methylpyrimidine with 4,4-dimethoxy-2-butanone and formamide [Organic Syntheses, Coll. Vol. 5, p.794 (1973); Vol. 43, p.77 (1963) [http://www.orgsynth.org/orgsyn/pdfs/CV5P0794.pdf Link] ] .

A novel method is by reaction of certain amides with carbonitriles under electrophilic activation of the amide with 2-chloro-pyridine and trifluoromethanesulfonic anhydride ["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] :

:

See also

* Purine
* Pyrimidine biosynthesis
* Pyrazine, an analog with the nitrogen atoms in positions 1 and 4
* Pyridazine, an analog with the nitrogen atoms in positions 1 and 2
* Simple aromatic rings
* ANRORC mechanism
*

References


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Look at other dictionaries:

  • Pyrimidine — Structure de la pyrimidine Général Nom IUPAC Pyrimidine …   Wikipédia en Français

  • pyrimidine — [ pirimidin ] n. f. • fin XIXe; all. Pyrimidin (1855); de pyridine et (a)mid(e) ♦ Biochim. Substance azotée dont la structure comporte une chaîne fermée, à 6 atomes, de formule C4H4N2. ● pyrimidine nom féminin Dénomination courante du composé… …   Encyclopédie Universelle

  • pyrimidine — [pə rim′ə dēn΄, pīrim′ə dēn΄; pir′ə mə dēn΄] n. [Ger pyrimidin < pyridin: see PYRIDINE] 1. a colorless, liquid, crystalline organic compound, C4H4N2, the fundamental form of a group of bases, some of which are constituents of nucleic acid 2.… …   English World dictionary

  • pyrimidine — pyrimidine. См. пиримидин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Pyrimidine — Dieser Artikel wurde aufgrund von Mängeln auf der Qualitätssicherungsseite der Redaktion Chemie eingetragen. Dies geschieht, um die Qualität der Artikel aus dem Themengebiet Chemie auf ein akzeptables Niveau zu bringen. Dabei können Artikel… …   Deutsch Wikipedia

  • pyrimidine — /puy rim i deen , pi , pir euh mi deen , din/, n. Biochem. 1. a heterocyclic compound, C4H4N2, that is the basis of several important biochemical substances. 2. one of several pyrimidine derivatives, esp. the bases cytosine, thymine, and uracil,… …   Universalium

  • Pyrimidine — One of the two classes of bases in DNA and RNA. The pyrimidine bases are thymine (T) and cytosine (C) in DNA and thymine (T) and uracil (U) in RNA. * * * 1,3 Diazine; a heterocyclic substance, the formal parent of several “bases” present in… …   Medical dictionary

  • pyrimidine — noun Etymology: International Scientific Vocabulary, alteration of pyridine Date: 1885 1. a feeble organic base C4H4N2 of penetrating odor 2. a derivative of pyrimidine; especially a base (as cytosine, thymine, or uracil) that is a constituent of …   New Collegiate Dictionary

  • pyrimidine — (pi rim i dĭn) A basic, heterocyclic, nitrogen containing molecule with one ring that occurs in nucleic acids and other cell constituents; pyrimidines are oxy or amino derivatives of the pyrimidine skeleton. The most important pyrimidines are… …   Dictionary of microbiology

  • pyrimidine — (= 1,3 diazine) A heterocyclic 6 membered ring, planar and aromatic in character. The parent compound of the pyrimidine bases of nucleic acid …   Dictionary of molecular biology


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