CH2 Bridge Research Articles

Alkane oxidation catalyzed by .mu.-oxo-bridged diferric complexes: a structure/reactivity correlation study

A series of μ-oxo-bridged diferric complexes, Fe 2 OL 4 X n (ClO 4 ) m , containing two bidentate nitrogen ligandes (L=2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, and 1,10-phenanthroline) and one exchangeable coordination site (X=H 2 O, Cl, CH 3 CO 2 , CF 3 CO 2 ) per iron were synthenized and characterized by their 1 H NMR, electronic, and Raman spectra and by their magnetic properties. 1 H NMR data showed that X=H 2 O or X=bridging CH 3 CO 2 were labile ligands while X=Cl was much less exchangeable. Complex 3D (L=4,4'-dimethyl-2,2'-bipyridine, X=CF 3 CO 2 , n=2, m=2) was characterized crystallographically

The Structure of the [1.1]Ruthenocenophane Dication: Metal–Metal Bond Formation and the Consequences of Proximity

Nonbonding Ru-Ru interactions in [1.1]-ruthenocenophane (1) that can be attributed to the proximity of the metal centers and the formation of a Ru-Ru single bond in the dication (12+) are the reason for the low oxidation potential of 1 and for the stability of 12+. As the X-ray structure analysis of the BF salt of 12+ shows (structure here viewed down the Ru-Ru bond), the two ruthenocene halves are distinctly twisted to accommodate the CH2 bridges.

Vibrational potentials of the low frequency out-of-plane motion in the ground and excited singlet electronic states of 9,10-dihydrophenanthrene

The absorption and single vibronic level fluorescence spectra of jet cooled 9,10-dihydrophenanthrene possesses long progressions of a low-frequency vibration identified as the out-of-plane nontotally symmetric CH2–CH2 bridge deformation. The intensity distribution in the observed progressions indicate that the molecule is nonplanar in the ground and the first two excited singlet electronic states described as the plus and minus combinations of the Lb states of the two perturbed benzene rings. The barrier height between the two equivalent nonplanar configurations, with the planar configuration being the transition state, is 2640 cm−1 in S0 and 1430 cm−1 in S1. These values are much larger than those in 9,10-dihydroanthracene. The observed intensity distributions are reproduced well by model calculations with double minimum potentials whose parameters are in good agreement with those obtained by geometry optimization and force field and vibrational frequency calculations by the quantum chemical force field π-electron method. The analysis yields the following values for the angle between the average planes of the two benzene rings: 18.4° in S0 and 12.1° in S1. It is shown that the origin of the S0→S2 transition lies ca. 240 cm−1 above the origin of the S0→S1 transition and that its doublet structure results from a near resonance vibronic interaction between the S1 and S2 states via a b mode of the calculated frequency of 221 cm−1.

Synthesis and NMR study of amide and imide derivatives of PMR‐15 monomeric units

AbstractVariations in PMR‐15 composite properties could be due to by‐products formed during the polymerization cycle. In order to identify these compounds, various condensation products derived from the three monomeric constituents of the resin: NE, BTDE, and MDA, have been synthesized and fully characterized by spectroscopic methods, mainly by 1H‐ and 13C‐NMR. In these products, one or two MDA amino groups are replaced by amido or imido groups, leading to mono‐ and di‐substituted MDA derivatives. Monosubstituted derivatives were obtained by first protecting one MDA amino group with a terbutoxycarbonyl group (Boc). The MDA's CH2 bridge of these molecules gives rise, in their 1H NMR spectra, to a characteristic resonance singlet, the position of which can be correlated to the nature of the amino substituents through 1H chemical shift increments. The latter provide a useful tool to predict the CH2, shifts in other compounds. Similar substituent increments are proposed for the chemical shifts of the MDA aromatic protons and carbon atoms.

ChemInform Abstract: Highly Unsaturated Macrocyclic Silicohydrocarbons.

ChemInformVolume 21, Issue 35 Organoelement Compounds ChemInform Abstract: Highly Unsaturated Macrocyclic Silicohydrocarbons. M. VORONKOV, M. VORONKOV Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorO. YAROSH, O. YAROSH Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorG. TURKINA, G. TURKINA Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorV. VITKOVSKII, V. VITKOVSKII Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorA. ALBANOV, A. ALBANOV Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this author M. VORONKOV, M. VORONKOV Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorO. YAROSH, O. YAROSH Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorG. TURKINA, G. TURKINA Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorV. VITKOVSKII, V. VITKOVSKII Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this authorA. ALBANOV, A. ALBANOV Inst. Org. Chem., Sib. Branch, Acad. Sci. USSR, 664033 Irkutsk, USSRSearch for more papers by this author First published: August 28, 1990 https://doi.org/10.1002/chin.199035223Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue35August 28, 1990 RelatedInformation

Highly unsaturated macrocyclic silicohydrocarbons

Nineteen 12-, 15-, 18-, 24- and 30-membered, highly unsaturated macrocyclic silicohydrocarbons containing -SiCCSi-, ( E)-SiCHCHSi- and -SiCH 2CH 2Si-fragments in the ring were synthesized by the reaction of Me 2Si(CCMgBr) 2 or BrMgCCMe 2SiCCSiMe 2CCMgBr with FMe 2SiCH 2CH 2SiMe 2F; ( E)-FMe 2SiCHCHSiMe 2F or ( E, E)-(ClMe 2SiCHCH) 2SiMe 2; ( E)-BrMgCCMe 2Si-CHCHSiMe 2CCMgBr or Me 2Si(CCSiMe 2CCMgBr) 2 with ( E, E)-(ClMe 2SiCHCH) 2SiMe 2; and Me 2Si(CCSiMe 2CCMgBr) 2, BrMgCCMe 2-SiCCSiMe 2CCSiMe 2CCSiMe 2CCMgBr or BrMgCCMgBr with ( E)-FMe 2SiCH  CHSiMe 2F under conditions of high dilution. Two 20-membered and one 26-membered macrocyclic silicohydrocarbons containing 6 or 8 silicon atoms bonded by 6 or 8 CC bonds and an endocyclic CH 2CH 2 or CHCH bridge were obtained for the first time by treating BrMgCCMe 2SiCCSiMe 2CCMgBr with Cl 2MeSiCH 2CH 2SiMeCl 2 or ( E)-F 2MeSiCHCHSiMeF 2, as well as Me 2Si(CCSiMe 2CCMgBr) 2 with ( E)-F 2MeSiCHCHSiMeF 2.

29Si and 13C NMR spectra of (E)-β-substituted 3-methoxy-4-trimethylsiloxystyrenes

NMR spectra of eleven (E)-β-substituted 3-methoxy-4-trimethylsiloxy-styrenes were measured under standard conditions that approach those of infinite dilution. The sensitivity of 29Si chemical shifts to the nature of (E)-β-substituent is high, in comparison with 4-substituted 2-methoxytrimethylsiloxybenzenes the insertion of a CH=CH bridge between the substituent and the benzene ring reduces the sensitivity by a factor of 1.5 only.

Structural aspects of polyimides. I. Polymerization and degradation of endo‐N‐phenylnadimide and endo‐N‐isobutylnadimide

AbstractThe isomerization, polymerization, and degradation aspects of endo‐N‐phenylnadimide and endo‐N‐isobutylnadimide (NPNI‐N and NIBNI‐N) were investigated using infrared analysis (IR), differential thermal analysis (DTA), gel permeation chromatography (GPC), thermogravimetric analysis (TG), and capillary gas chromatography‐mass spectroscopic (GC–MS) techniques. Although the endotherm related to the retro‐Diels–Alder reaction is not registered in the DTA thermographs, on‐line mass spectrometric studies revealed the occurrence of this process. The formation of the Diels–Alder adduct of cyclopentadiene with N‐isobutylnadimide (NIBNI) during the polymerization of NIBNI‐N is proved. GPC studies on NPNI‐N and NIBNI‐N cured at 300°C for 3.0 h showed the average degree of polymerization to be three to four. The polymers obtained by curing NPNI‐N and NIBNI‐N at 300°C for 3.0 h showed 109.8 kJ/mol as the activation energy for degradation. The dynamic and isothermal pyrolysis studies clearly indicated the presence of intact norbornyl units in the polymer, and the breakage of CH2 bridges in the strained norbornyl structural elements was found to be the point of aromatization during degradation.

The influence of fluoro substituents on cyclopropa-benzene, -naphthalene, and -anthracene

The He(Iα) PE spectra of cyclopropabenzene, cyclopropa[b]naphthalene, cyclopropa[b]anthracene, their 1,1-difluoro derivatives and of some of their substituted derivatives have been recorded, analyzed and assigned by correlation with the PE spectra of the parent molecules benzene, naphthalene and anthracene. It is shown that the PE spectroscopic data yield no information about the presence or absence of a Mills-Nixon effect in the molecules investigated. The inductive effect of the bridging CH2 group of the cyclopropeno ring is close to zero, whereas that of the CF2 group leads to positive ionization energy shifts in good agreement with previous experience. The hyperconjugative interaction of the local pseudo-π orbital of the CH2 group yields a significant destabilization of the π-orbitals of B1 symmetry.

Crystal structures and photoelectron spectra of some trimethanoanthracenes, tetramethanonaphthacenes, and pentamethanopentacenes. Experimental evidence for laticyclic hyperconjugation

Photoelectron (p.e.) spectra of the series of dienes (4), (10), (11a)–(13a), and crystal structures for the dodecachlorodienes(11b)–(13b) are reported. The spectra revealed large π-splitting energies of 0.32 and 0.52 eV for (4) and (11a) respectively. The value of (4) is attributed to the presence of orbital interactions through six σ bonds (OIT-6-B), and this, taken with the p.e. data for the dienes (1)–(3), provides convincing evidence for the long-range nature of OIT-n-B. The larger π-splitting energy of 0.52 eV observed for (11a), compared with (4), has been explained in terms of the presence of two reinforcing orbital interactions: OIT-6-B and a new variant of hyperconjugation, called laticyclic hyperconjugation, in which the π MOs of the double bonds mix with the ψπ MO of the central CH2 bridge of (11a). The surprisingly large π-splitting energy of 0.29 eV observed for (12a) is also due largely to laticyclic hyperconjugation involving both pairs of symmetry adapted ψπ MOs of the CH2 bridges. No π-splitting energy could be detected in the p.e. spectrum of (13a). From the crystal structures of (11b)–(13b), it was found that the distance between neighbouring CH2 groups, and between a double bond and its closest CH2 neighbour is about 3 A in all three compounds. HF/STO-3G calculations on model ethene ⋯(CH4)n⋯ ethene complexes suggest that laticyclic interactions, like OIT-n-B, are very long-range processes, the predicted π-splitting energies amounting to ca. 10–3 eV for two double bonds separated by ca. 33 A. The relevance of these orbital interactions to biological electron-transfer processes is briefly discussed.

M.m]Metallocenophanes: Synthesis, Structure, and Properties

AbstractMetallocenophanes are metallocenes in which the cyclopentadienyl ligands are linked intramolecularly through CmHn or CmHnX (X = heteroatom) chains. Two main classes of metallocenophanes are known: in [m]metallocenophanes the ligands of one metallocene are connected by a bridge (or by several bridges); in [m.n]metallocenophanes two (or more) metallocenes are brought together into one molecule by bridging groups. This article briefly describes the first class (mononuclear complexes) and then concentrates on the second (binuclear complexes). The [1.1]metallocenophanes, which are produced by linking two metallocene moieties through two C1, bridges, are of particular interest and are characterized by a variety of unusual and useful properties: they are very flexible conformationally; hydride abstraction from the CH2 bridges produces carbenium ions that are greatly stabilized by the adjacent metallocene moieties; deprotonation of one of the CH2 bridges is surprisingly easy and leads to the unusual situation that an intramolecular CHċC hydrogen bond stabilizes a carbanion; protonation of both metallocene moieties causes the liberation of one mole of hydrogen per mole of [1.1]metallocenophane, thereby allowing the use of these compounds as catalysts for the formation of hydrogen in acidic aqueous solutions.

The reactions of di-µ-methylene-bis(pentamethylcyclopentadienyl)-dirhodium(IV) complexes with benzylmagnesium chloride and with alkynylmagnesium chloride; X-ray structure of [(η5-C5Me5)Rh(CH2Ph)(µ-CH2)2Rh(η4-C5Me5CH2Ph)

Reaction of trans-[(C5Me5)2Rh2(µ-CH2)2Cl2](1) with RCCMgCl gave trans-[(C5Me5)2Rh2(-µ-CH2)2(RC2)2](R = Ph or But). However attack on (1) by benzylmagnesium chloride occurred at one C5Me5 ring as well as at one rhodium to give [(η5-C5Me5)Rh(CH2Ph)(µ-CH2)2Rh(η4-C5Me5CH2Ph)](6). The structure of (6) has been deduced by n.m.r. spectroscopy and confirmed by a single-crystal X-ray structure determination which showed the two rhodiums [2.559(3)Å apart] to be linked by two µ-methylene bridges. One rhodium (oxidation state formally +4) bears a σ-benzyl and an η5-C5Me5 ring; the other rhodium (formally +2) is η4-bound to C5Me5CH2Ph where the benzyl on the C5 ring is exo to the metal. Reaction of [(C5Me5)2Rh2(η-CH2)2(MeCN)2][PF6]2 with R′CCH gave a complex [(C5Me5)2Rh2(µ-CH2CHCR′CHCR′CH)]PF6(7)(R′=p-chlorophenyl); on the basis of the n.m.r. spectra it is proposed that the two rhodiums are linked by a σ,σ,η5-CH2CHCR′CHCR′CH bridge. The mode of formation of these complexes is discussed.

Mixed-ligand complexes of diruthenium(II, III): Syntheses and molecular structures of chloro-bis-(acetato)-bis-(2-anilinopyridinato)(2-anilinopyridine)diruthenium·methylene chloride and chloro-(acetato)-tris(6-chloro-2-oxypyridinato)diruthenium·methylene chloride

The compound Ru 2Cl(O 2CCH 3) 2(PhNpy) 2(PhNHpy)·CH 2Cl 2 ( 1) was prepared by reacting Ru 2Cl(O 2CCH 3) 4 and PhNHpy (in 1:3 molar proportions) in boiling methanol and crystallized by slow evaporation of a solution of the compound in a CH 2Cl 2-hexane mixture. The compound Ru 2Cl(O 2CCH 3)(chp) 3·CH 2Cl 2 ( 2) was obtained in a similar way with a 1:4 molar proportion of starting acetate to Hchp. While 1 is dark blue in color, 2 is purple. Both compounds are soluble in common organic solvents other than hexane and are indefinitely stable in air. Compounds 1 and 2 crystallize in the triclinic space group P 1 and the orthorhombic space group Pnma, respectively, with the following unit cell dimensions: 1, a = 12.093(2) Å, b = 12.143(3) Å, c = 14.357(3) Å, α = 94.94(2)°, β = 114.15(2)°, γ = 92.01(2)°, V = 1911(1) Å 3, and Z = 2; 2, a = 16.912(5) Å, b = 15.975(4) Å, c = 10.329(6) Å, V = 2791(2) Å 3, and Z = 4. The structures of 1 and 2 were refined to R = 0.044 ( R w = 0.062) and R = 0.058 ( R w = 0.066), respectively. In 1, the diruthenium(II, III) unit is bridged by two acetate and two 2-anilinopyridine anionic ligands (both oriented in the same direction) in trans-disposition. The axial positions are occupied by a Cl anion and a neutral PhNHpy ligand. The metal atom bonded to two equatorial pyridine nitrogen atoms has the Cl axial coordination. The amine hydrogen atom of the other axial ligand is hydrogen bonded to one bridging acetate group. The RuRu, RuCl and RuN(axial) distances in 1 are 2.308(1) Å, 2.560(2) Å, and 2.457(6) Å, respectively. The RuN (equatorial) and RuO distances are in the ranges 2.024(5)–2.098(6) Å and 2.030(5)– 2.055(4) Å, respectively. In 2, a polar arrangement of three bridging chp ligands around the diruthenium(II, III) unit is also present, along with one bridging CH 3CO 2 − ligand. The ruthenium atom which is bonded to four oxygen atoms has an axially coordinated Cl ion. The axial site of the other ruthenium atom, which is bonded to three N and one O atoms, is empty because of the three Cl atoms of the chp ligands that project into this axial site. The RuRu and RuCl distances in 2 are 2.282(4) Å and 2.474(9) Å, respectively. The RuN and RuO distances lie in the ranges 2.06(2)–2.11(2) Å and 1.95(2)–2.03(2) Å, respectively. Electronic spectra of the solutions of 1 and 2 in CH 2Cl 2 display bands at 695 nm (ϵ = 6560 M −1 cm −1) and 535 nm (ϵ = 3990 M −1 cm −1), respectively.

Comparison of Activities of the Host-Specific Toxin of Helminthosporium maydis, Race T, and a Synthetic C41 Analog

It previously had been proposed that the host-selective toxin of Helminthosporium maydis race T consists of a series of unusual linear (C(35) to C(45))polyketols, of equal toxicity on a weight or molar (10(-8)-10(-9)) basis. Previous laboratory synthesis of T-toxin analogs was limited to shorter (C(15) to C(26)) versions which possessed the requisite specificity for susceptible corn (Zea mays) but were less toxic on a weight or molar (10(-6)-10(-7)) basis. In the present study, a C(41) analog with four beta-ketol units spaced by CH(2) bridges as in native toxin has been synthesized. On a weight or molar basis, it is as effective as native toxin or its purified components in stimulating NADH oxidation of mitochondria from susceptible corn, thus providing firm evidence for the correctness of the proposed structures of T-toxin. Additional support derives from the observation that C(24) and C(26) analogs with -(CH(2))(4)- and -(CH(2))(6)- bridges between ketol groups are not as effective in stimulating NADH oxidation as are C(23) and C(25) analogs with the -(CH(2))(3)- and -(CH(2))(5)- bridges of native T-toxin.It was calculated that a single molecule of the C(41) analog is at least 300 times more effective in stimulating mitochondrial oxidation than a molecule of the C(23) or C(25) analogs. This emphasizes the importance of chain length for toxicity, perhaps through perturbation of membrane functions of mitochondria and/or chloroplasts.

A covalent model for the bonding of adsorbed hydrocarbon fragments on the (111) face of platinum

A systematic molecular orbital study of the location of CH n and C-CH n ( n = 1, 2, 3) species on a Pt(111) single-crystal surface has been performed by using both a cluster model and a band structure calculation within the framework of the Extended Hückel Theory (EHT). These species may be involved in the hydrogenation/dehydrogenation processes of hydrocarbons. The observed dependence of the adsorption site on the number of hydrogens in the CH n fragments suggests that any C-H bond breaking in CH n species must involve a change of adsorbate bonding site. The carbon is found to be located on the surface in such a way as to complete its tetravalancy. Thus, CH occupies a three-fold coordinated hollow site, CH 2 a two-fold coordinated bridge site and CH 3 a one-fold coordinated top site. C-CH 3 is found to be perpendicular to the surface in a three-fold hollow site in agreement with experimental observations. It is also found that a displacement of C-CH 2-R to a top site makes a β C-R cleavage easier.

Photodissociation Reaction from Higher Excited Triplet States of [2.2]Paracyclophane

Abstract The mechanism of photodissociation of [2.2]paracyclophane in glassy solvent at 77 K was studied. It is concluded that the dissociation of the CH2–CH2 bridge occurs from higher triplet states (Tn) via the lowest triplet state as an intermediate. The efficiency of the reaction depends on the characters of Tn states; high from the locally excited state, and low from the charge-transfer state.

Übergangsmetall-methylen-komplexe : IX. Molekülstruktur von μ-methylen-bis[dicarbonyl(η 5-methylcyclopentadienyl)mangan](MnMn), μCH 2[(η 5-CH 3C 5H 4)Mn(CO) 2] 2

The structure of μ-methylenebis[dicarbonyl(η 5-methylcyclopentadienyl)-manganese](MnMn) has been established by means of X-ray diffraction techniques to consist of two (η 5-C 5H 4CH 3)Mn(CO) 2 fragments which are linked by a bridging CH 2 ligand and a metal to metal bond. Dimetallacyclopropanes of this type can easily be distinguished from the related Fischer-type carbenes as well as from μ-alkylidene complexes without metalmetal bonds by 13C NMR spectroscopy.

Synthesis of some diplatinum complexes, including bis-µ-[bis(diphenylphosphino)methane]-µ-methylene-dichlorodiplatinum, [Pt2Cl2(µ-CH2)(µ-Ph2PCH2PPh2)2], from [Pt2Cl2(µ-Ph2PCH2PPh2)

A number of diplatinum complexes including [Pt2Cl2(µ-CH2)(µ-dppm)2][dppm = bis(diphenylphosphino) methane], the first diplatinum complex containing a bridging CH2 group, and complexes [Pt2Cl2(µ-X)(µ-dppm)2](X = S and SO2) and [Pt2L2(µ-dppm)2][PF6]2(L = a monodentate ligand) have been prepared from [Pt2Cl2(µ-dppm)2].

Crystal and molecular structure of di-µ-trimethylsilylmethyl-bis[(tri-methylphosphine)(trimethylsilylmethyl)chromium(II)](4 Cr–Cr)

The crystal and molecular structure of the title compound has been determined by direct methods and refined by least squares to R 0.029 3 based on 4 345 diffractometer data. Crystals are triclinic with a= 16.975(7), b= 11.396(6), c= 10.678(6)A, α= 114.87(7), β= 91.75(7), γ= 84.98(7)°, space group P, and Z= 2. The binuclear molecule possesses an approximate two-fold axis and contains two bridging alkyl groups arranged in a cis configuration. One H atom from each bridging CH2 group makes a close contact (ca. 2.25A) with one of the metal atoms, introducing a slight asymmetry in the Cr–C bridge bonds. The short Cr–Cr distance [2.1007(5)A] is consistent with the presence of a quadruple metal–metal bond. However, in order to account for the overall coordination geometry, and in particular the accommodation of the two cis electron-deficient bridges, it is suggested that the M[graphic omitted]M system is bent. A simple description of this in terms of d-orbital overlap integrals is presented.

Interactions Between Anthocyanins, Phenolic Compounds, and Acetaldehyde and Their Significance in Red Wines

Interactions between pure anthocyanins [malvidin (Mv) 3-glucoside, Mv 3,5-diglucoside, and Mv 3-p-coumarylglucoside-5-glucoside], phenolic compounds [ (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, procyanidin dimer B2, and procyanidin trimer C1], and acetaldehyde were studied in tartrate buffer, pH 3.5, at room temperature in air under darkness and light. Several reactions occurred simultaneously. The anthocyanins and phenolic compounds reacted very slowly, with eventual formation of yellow xanthylium salts (one presumed glycosylated, others sugar-free), confirming that condensation occurred via the anthocyanin 4-position. Unreacted procyanidins B2 and C1 were partly transformed to epicatechin and lower and higher polymeric procyanidins, the reactions being catalyzed by daylight. There was little reaction between the anthocyanins and acetaldehyde except with Mv 3-glucoside, which was slowly polymerized. However, the addition of acetaldehyde to mixtures of anthocyanins and phenolics caused rapid and spectacular color augmentation with shifts toward violet, with extent of the shift varying with the type of component. The orders of decreasing reactivity were Mv 3-glucoside > Mv 3-p-coumarylglucoside-5-glucoside > Mv 3,5-diglucoside, and trimer C1 = dimer B2 > epicatechin. Conversely the extent of color increase and its stability decreased in reverse order, with Mv diglucoside > acylated diglucoside > monoglucoside, because of precipitation with the latter. Color augmentation was due to the formation of highly colored new compounds, detectable by chromatography and believed to consist of anthocyanins and phenolics linked by CH₃CH bridges. A reaction scheme is proposed in which the initial reaction product of acetaldehyde and phenolic combines with the anthocyanin at position 8, followed by anhydrobase formation. A small amount of a compound resulting from interaction of Mv 3,5-diglucoside, (+)-catechin, and acetaldehyde was isolated and its properties examined. The significance of the findings are discussed in relation to color changes of red wines.