Chemistry of Heterocyclic Compounds, Vol. 46, No. 12, March, 2011 (Russian Original Vol. 46, No. 12, December, 2010)
X-RAY DIFFRACTION AND QUANTUM-CHEMICAL
ANALYSIS OF A SINGLE CRYSTAL OF 2,5-DIMETHYL-
3,4-DIHYDRO-2H-PYRAN-2-CARBOXYLIC ACID
Ya. P. Kovalskyi
1
*, V. V. Kinzhybalo
2
, N. M. Karpiak
1
, and G. O. Marshalok
1
The structure of synthesized 2,5-dimethyl-3,4-dihydro-2H-pyran-2-carboxylic acid was investigated by
the single crystal X-ray diffraction analysis method. It was established that the molecule of the acid
exists in the form of the endo isomer while the single crystal exists as a racemate of the two
enantiomeric endo stereomers. Quantum-chemical calculations of a model of the macrocell of the acid
by means of the semiempirical MOPAC2009 program agree well with the X-ray diffraction data.
Keywords:
2,5-dimethyl-3,4-dihydro-2H-pyran-2-carboxylic acid, quantum-chemical calculations,
MOPAC2009, RM1, single crystal X-ray diffraction analysis, Winmostar.
Pyran derivatives and the dimers of acrolein and its homologs in particular are valuable starting
substances for the synthesis of dyes, plasticizers, surface-active substances, fungicides, insecticides, and drugs
[1]. The dimers of α-alkylacroleins are synthesized by the Diels–Alder reaction, and their subsequent
disproportionation in an alkaline medium by the Cannizzaro reaction leads to the formation of oxidation
products (the salts of pyrancarboxylic acids) and reduction products (pyran alcohols) [2].
O
CH
2
R
O
CH
2
R
O
R
R
CHO
O
R
R
CHO
O
R
R
CH
2
OH
O
R
R
COONa
O
R
R
COONa
O
R
R
COOH
+
2
NaOH
+
H
+
_______
* To whom correspondence should be addressed, e-mail: yakovalskyi@polynet.lviv.ua.
1
Lviv National Polytechnic University, Lviv 79013, Ukraine.
2
Wroclaw University, Chemical Faculty, Wroclaw 50-383, Poland; e-mail: kinzhybalo@gmail.com.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12. pp. 1788-1794, December, 2010.
Original article submitted June 8, 2010.
0009-3122/11/4612-1443©2011 Springer Science+Business Media, Inc. 1443