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A peak in the gas chromatographic profile of beer: Nylon adsorbates has been found to comprise three unresolved biflavan components. One of these, molecular formula C30H26O12, consists of two C—C linked catechin units and has the same structure as a biflavan obtained by the acid catalysed interaction between cyanidiol and catechin. It appears to be the same as the procyanidin previously isolated from beer. The other components, both with molecular formula C30H26O13, have the same skeletal structure as the first, but are linked catechin-gallocatechin pairs, one being a prodelphinidin, the other a procyanidin. Dicatechin, a tannin obtained by treatment of catechin with dilute mineral acid, also seems likely to be a component of the adsorbate profiles.

During prior investigations into the important beer flavor component dimethyl sulfide, traces of other sulfur compounds appeared in gas chromatographic profiles obtained with a flame photometric de...

A methanol-soluble fraction of beer-Nylon 66 adsorbates has been examined by gas chromatography using enhanced volatilities afforded by trimethylsilylation. Mass spectrometry was used to assign structures to several profile components which included fatty acids, residual wort carbohydrates and phenols. The latter comprised free acids, the most prominent being p-hydroxy-cinnamic and ferulic acids, catechins, a catechin glycoside, dicatechin and condensed biflavans. Flavonoids were not observed. The profiles can be used to gain information, which has hitherto been unavailable from paper and thin layer chromatographic studies, on the relative concentrations of adsorbate components. PVP-adsorbate profiles contained the same phenols as were observed in the Nylon profiles.

Trans-2-nonenal, 3-hydroxynonanal and 3-hydroxybutanal were isolated from barley and wort and mass spectral evidence for the presence of further hydroxyaldehydes was found. The concentration of free aldehydes in a model solution was found to decrease in the presence of bisulphite. Addition of acetaldehyde to a mixture of aldehyde bisulphite complexes released trans-2-nonenal in preference to other aldehydes. The concentration of sulphite in beer decreased by 66% over four months. This data was combined in a theory in which the papery, cardboard stage of beer staling is ascribed to a decrease in bisulphite concentration and subsequent bisulphite transfer from unsaturated aldehyde bisulphite addition complexes.

Bisulfite addition complexes were utilized in a method devised to obtain extracts suitable for the relatively rapid isolation and identification of beer carbonyl components as their oxime derivativ...

Structure 1 is proposed for sibiricine, a minor alkaloid of C. sibirica. The structural assignment rests on an interpretation of its mass spectrum and its proton magnetic resonance (p.m.r.) spectrum.

Structure 1 is proposed for ochrobirine from an analysis of the proton magnetic resonance spectra of ochrobirine and its di-O-acetate.

The minor alkaloids of B. arborea have been identified. Three of them have been shown to be dihydro-sanguinarine, oxysanguinarine, and 11-O-methyldihydrochelerythrine respectively. The structure of the fourth has been established by physical methods and by synthesis as the hitherto unknown 1,3-bis(11-hydrochelerythrinyl)acetone. It does not appear to be an artefact. The high resolution mass spectra of some dihydrochelerythrine derivatives are discussed.

A series of 1- and 2-substituted indanes have been treated with hexacarbonylchormium in three solvents : diglyme, decalin, and cyclohexanol. The ratios of cis- to trans-tricarbonyl(indane)chromiums thus obtained have been shown to be thermodynamically controlled, as individual isomers come to equilibrium under the conditions used. The ratio are discussed in terms of non-bonded interactions between the substituent and the chromium carbonyl group. Some unusual cases of preferred stabilisation of cis-isomers have been found.

The n.m.r. spectrum of tricarbonyl-(trans-1,3-dimethylindane)chromium (I; M = Cr) shows separate signals for the four aromatic protons, the separation being sufficient for the spectra to be considered first order. The aromatic regions of the spectra of other cis-tricarbonyl-(1-substituted indane)chromiums show similar properties, in contrast to the spectra of the corresponding trans-isomers. The signal separation in the case of the cis-isomers is attributed to the tricarbonylchromium residue adopting a preferred conformation in which steric interactions with the bulky cis-substituent are minimised.

The dipole moments of cis- and trans-tricarbonyl-(2-cyanoindane)chromium have been measured. The results indicate that in both isomers the cyano-group prefers a pseudo-equatorial conformation. 2-Cyano-5,6-dibromo-indane has been synthesised but its measured moment gives no clear indication of a preference for either the pseudo-equatorial of pseudo-axial conformation by the cyano-group.

Reaction of tricarbonyl(trispyridine)chromium with 1- and 2-hydroxyindanes in the presence of boron trifluoride etherate gave in each case pure cis-tricarbonyl(hydroxyindane)chromium together with some pentacarbonyl(pyridine)chromium. 1-Methoxyindane also gave exclusively cis-tricarbonyl compound and the reactions have been shown to be kinetically controlled. These results are compared with the similar stereospecificity of the Simmons–Smith reaction with some hydroxy- and alkoxy-cyclic olefins. The early stages of the reaction of hexacarbonylchromium with hydroxy- and methoxy-indanes also appear to be partially kinetically controlled and the formation of cis-isomers is preferred. The reactions of tricarbonyl(trispyridine)chromium with other substituted indanes are discussed.