Formaldehyde theoretical studies

Initiated by the pioneering work of Burawoy [51 ], a number of experimental and theoretical studies were performed on the carbonyl group [52-55]. A complete review is beyond the scope of this paper. We will mention only some of them that we consider of particular importance for a comprehensive coverage of the electronic spectrum of formaldehyde for both the theoretical and experimental points of view. 

These trends agree well with recent theoretical studies, which found that several neighboring (three) Pt atoms are required for methanol dehydrogenation [Desai et al., 2002 Greeley and Mavrikakis, 2002, 2004 Okamoto et al., 2003 Cao et al., 2005], while these requirements are less stringent for formaldehyde dehydrogenation [Desai et al., 2002 Greeley and Mavrikakis, 2002]. 

Barone, V. and C. Adamo. 1994. Theoretical study of direct and water-assisted isomerization of formaldehyde radical cation. A comparison between density functional and post-Hartree-Fock approaches. Chem. Phys. Lett. 224, 432. 

The theoretical studies showed that the [2 4-2] cydoaddition reactions with alkenes or alkynes were almost barrierless and very exothermic. The exothermicity for alkynes (—42.8 kcal mol ) was found to be greater than that for alkenes (—21.3 kcal mol ). Scheme 4.21b shows the calculated [2 4- 2] cydoaddition with polar unsaturated molecules, formaldehyde and FICN. The barriers (3.6kcalmol for formaldehyde and 9.0 kcal mol for HCN) are slightly higher than those in the reactions with alkenes and alkynes. The exothermicity is also significant (—26.5 for formaldehyde and —37.4 for HCN). 

Ab initio and density functional theoretical studies of the 4 + 2-cycloaddition of 2-azabutadiene with formaldehyde predict a concerted reaction that agrees well with experimental evidence.184 The azadiene A-plienyl-l-aza-2-cyanobuta-l,3-diene reacts with electron-rich, electron-poor, and neutral dipolarophiles under mild thermal conditions.185 5,6-Diliydro-4//-1,2-oxazines have been shown to be usefiil as synthon equivalents of 2-cyano-l-azabuta-1,3-dienes.186 The intramolecular Diels-Alder reaction of 1-aza-l,3-butadienes (106) can be activated by a 2-cyano substituent (Scheme 37).187 Stereoselectivity in the hetero-Diels-Alder reactions of heterobutadienes, nitrosoalkenes, and heterodienophiles has been extensively reviewed.188 The azadiene l-(f-butyldimethylsilyloxy)-l-azabuta-1,3 -diene (107) reacts with halobenzo-quinones, naphthoquinones, and A-phcnylmalcimidc to yield low to good yields of various pyridine heterocycles (108) (Scheme 38).189 The 4 + 2-cycloaddition of homophthalic anhydride with A-(cinnamylidcnc)tritylaminc produces the 3,4-adduct whereas with A -(cinnamylidcnc)bcnzylidinc the 1,2-adduct is produced.190... 

Lu X, Zhang Q, Lin MC (2001) Adsorptions of Methanol, Formaldehyde and Formic Acid on die Si(100) —2x 1 Surface A Theoretical Study, Phys. Chem. Chem. Phys. 3 2156-2166... 

Ashby and Boone s proposed mechanism was not verified until 2001, when Luibrand et al. carried out a theoretical study on the lithium aluminum hydride reduction of formaldehyde6 (Scheme 4.III). Two types of complexes are possible between formaldehyde and LiAlFLt, depending on the geometry of LiAlFLt complex A is from tridentate r 3-LiAlFLt, and complex B is from bidentate ri2-LiAlH4.7 Calculations indicate that the intermediate product OLiAl would be formed via six-membered transition state A, derived from complex A, which is more stable than transition state B by 2.0 kcal/mol. 

Ohrn, A. and Karlstrom G., A theoretical study of the solvent shift to the n-p transition in formaldehyde with an effective discrete quantum chemical solvent model including non-electrostatic perturbation. Mol. Phys. (2006) 104 3087-3099. 

Good test cases would be the solvent effects on the UV-vis absorption spectra of formaldehyde and acetone that have been the subject of innumerous theoretical studies. Innovative theoretical methods have been applied to formaldehyde (see also the compilation of results in [20,32,113,114,115,116]). Unfortunately the experimental result for formaldehyde in water is not clear because of chemical problems mostly associated to the aggregation and formation of oligomers. Therefore a better test case is the UV-vis spectra of acetone, because reliable experimental solvent shifts and several theoretical results are available (see the compilation of results in [117]). The Stokes shift of the n-rr transition of acetone has been critically discussed by Ohrn and Karlstrom [118], Grozema and van Duijnen [17] studied the solvatochromic shift of the absorption band of acetone in as much as eight different solvents. Acetone is known to shift the maximum of the n-rr band by 1500-1700 cm 1 when immersed in water [119,120,121], Using the conventional HF/6-31 G(d) point charges, Coutinho and Canuto [54] simulated acetone in water and performed INDO/CIS... 

Masella M, Flament J-P (1999) A theoretical study of five water/ammonia/formaldehyde cyclic trimers Influence of cooperative effects. J Chem Phys 110 7245-7255... 

Dimitrova, Y. and Peyerimhoff, S. D., Theoretical. study of hydrogen-bonded formaldehyde-water complexes, J. Phys. Chem. 97, 12731-12736 (1993). 

PhCH2NPPh3 affords the isocyanide derivative [Os3(CO)g(CNCH2Ph)(n3-ri rri iTi -Ceo)]. The Staudinger reaction in combination with an intramolecular aza-Wittig ring closure reaction has been applied in the synthesis of quinazolin-4-ones. Other examples of intramolecular aza-Wittig reactions are reported as parts in multi-step synthetic routes. A theoretical study of the aza-Wittig reaction of HN = PX3(X = H and Cl) with formaldehyde in the gas phase and in solution has been reported. ... 

Most of the early theoretical studies of Lewis acid catbonyl interactions focused on alkali metal cations such as Li and Na, partly due to the significance of such interactions in biological systems and partly due to computational limitations. In 1973 some of the first calculations on the formaldehyde/Li system were performed. Using both ab initio (SCF-LCAO-MO) and semiempirical (CNDO/2) methods the researchers found that in the ground state the complex possesses Civ symmetry in which Li lies on the axis of the carbonyl C—O bond with an O— Li distance of 1.77 A. 

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