GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART II. THE DEHYDRATION PRODUCTS OF α-TERPINEOL

1961 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
E. Von Rudloff
Keyword(s):  
Liquid Chromatography ◽  
Oxalic Acid ◽  
Complex Mixture ◽  
Reaction Times ◽  
Gas Liquid Chromatography ◽  
Minor Components ◽  
Reaction Products ◽  
The Third ◽  
Major Reaction ◽  
Trace Constituents

The complex mixture of terpenes obtained on dehydrating α-terpineol with aqueous oxalic acid was almost completely separated by gas–liquid chromatography (GLC), using rapeseed oil as a new liquid phase. Terpinolene, dipentene, α- and γ-terpinene, Δ2,4(8)-p-menthadiene, and 1,8-cineole were identified as the major reaction products; three minor and seven trace constituents were also detected. One of the minor components was p-cymene, one an oxide, and the third an unidentified hydrocarbon. The yield of these components after different reaction times was determined by GLC. The initial dehydration gives terpinolene and dipentene in the ratio of approximately 2:1. Terpinolene is isomerized to α- and γ-terpinene, Δ2,4,(8)-p-menthadiene, and the unidentified hydrocarbon, but not to dipentene. 1,8-Cineole and the other oxide are formed in a reversible reaction. Dehydration of α-terpineol with several other acidic reagents yielded mixtures of products similar to that obtained with aqueous oxalic acid. With acetic acid or acetic anhydride, however, dipentene was formed preferentially and this reaction appears to proceed via the derived acetate.

Study of photolysis of 1,3-bis(4-nitrophenyl)-1-butene in acetonitrile and 2-propanol

1983 ◽  
Vol 48 (1) ◽  
pp. 279-285
Author(s):  
Gabriel Čík ◽  
Ľubomír Lapčík ◽  
Anton Blažej ◽  
Igor Šurina
Keyword(s):  
Liquid Chromatography ◽  
Reaction Mechanism ◽  
Mass Spectroscopy ◽  
Uv Spectra ◽  
Gas Liquid Chromatography ◽  
Mercury Lamp ◽  
Reaction Products ◽  
Polychromatic Radiation

Photolysis of 1,3-bis(4-nitrophenyl)-1-butene (I) in acetonitrile and 2-propanol by polychromatic radiation of a mercury lamp was studied. The photolysis kinetics was followed by UV spectra and the reaction products were analysed by IR and mass spectroscopy and by gas-liquid chromatography. The reaction mechanism in markedly affected by the presence of oxygen. Photolysis of I in acetonitrile gives mainly 4-nitrobenzaldehyde, n-heptane and toluene, in 2-propanol the principal products are stereoisomeric 1,3-diphenyl-1-butenes.

Neutral volatiles in cheddar cheese made aseptically with and without starter culture

1968 ◽  
Vol 35 (2) ◽  
pp. 237-245 ◽  
Author(s):  
W. A. McGugan ◽  
Shirlie G. Howsam ◽  
J. A. Elliott ◽  
D. B. Emmons ◽  
B. Reiter ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Starter Culture ◽  
Cheddar Cheese ◽  
Volatile Components ◽  
Gas Liquid Chromatography ◽  
Dimethyl Sulphide ◽  
The Third ◽  
Chromatographic Columns

SummaryAnalyses of the neutral volatile components from 3 Cheddar cheese are presented. Two were made aseptically in an aseptic vat, with and without starter culture; the third was made with starter culture in an open vat. Gas–liquid chromatography and mass spectrometry detected the same volatiles in starterless cheese having little or no Cheddar flavour as in cheese made with starter and having a characteristic Cheddar flavour. Methyl disulphide and dimethyl sulphide were the only compounds consistently detected in higher concentrations in the cheese made with starter than in the cheese made without starter. However, using a total trapping technique, it was found that the combination of components recovered from the effluents of the chromatographic columns did not have the cheese-like aroma of the distillate vapours that were injected. Reasons for this are discussed.

GLC Determination of β-Hydroxybutyric Acid in Decomposed Eggs: Separation from a Complex Mixture Containing an Unknown Interference

1972 ◽  
Vol 55 (5) ◽  
pp. 1142-1144
Author(s):  
Walter F Staruszkiewicz ◽  
John F Bond
Keyword(s):  
Liquid Chromatography ◽  
Retention Time ◽  
Complex Mixture ◽  
Principal Component ◽  
Gas Liquid Chromatography ◽  
Hydroxybutyric Acid ◽  
Processing Equipment

Abstract A sample of frozen decomposed egg, which was analyzed by using official first action method 17.034–17.038, was found to exhibit several extraneous peaks. One of the peaks had the same retention time as β-hydroxybutyric acid, which has been previously associated with incubator-reject eggs. Since the samples were known to contain no incubator-reject eggs, gas-liquid chromatography on several columns was performed to determine whether or not the peak represented β-hydroxybutyric acid. Separations performed on 5 different columns demonstrated that the principal component of the questionable peak was not β-hydroxybutyric acid. The presence of the compound may have been the result of contamination by processing equipment or sample containers.

GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART VIII. THE VOLATILE OIL OF TANACETUM VULGARE L.

1963 ◽  
Vol 41 (7) ◽  
pp. 1737-1743 ◽  
Author(s):  
E. von Rudloff
Keyword(s):  
Liquid Chromatography ◽  
Chemical Composition ◽  
Volatile Oil ◽  
Gas Liquid Chromatography ◽  
Minor Components ◽  
Tanacetum Vulgare ◽  
Retention Characteristics ◽  
Local Plants ◽  
Methylene Group ◽  
Commercial Oil

The chemical composition of the commercial oil of tansy and of that obtained from a local tansy species was determined by means of gas–liquid chromatography. Both oils contained d-isothujone as the major component (68.5%, 58%). The commercial oil contained fairly large amounts of l-camphor (13.9%), whereas that from local plants had only traces of camphor and 19.8% of l-thujone. The minor components isolated and identified in both oils were l-α -pinene, l-camphene, d-sabinene, d-limonene, 1:8-cineole, γ-terpinene, p-cymene, d-terpinen-4-ol, l-carvotanacetone, and l-borneol. Small amounts of α-thujene, β-pinene, α-terpinene, terpinolene, neoisothujyl and isothujyl alcohols, and dihydrocarvone were identified by retention characteristics only. Car-4-ene, isomeric alloocimenes, and carvomenthone may also be present. An unknown, crystalline monoterpene alcohol with a terminal methylene group was isolated in small amounts. A sesquiterpene (3.7%) was obtained from the oil of local plants.Prefractionation of these oils by fractional distillation resulted in extensive isomerization of isothujone to dl-carvotanacetone. Such a rearrangement was not encountered during prefractionation by preparative gas–liquid chromatography.

Preparation of some trimethyl- and methylethylbiphenyls and reactivity of aromatic hydrocarbons in the Gomberg reaction

1980 ◽  
Vol 45 (11) ◽  
pp. 3140-3149 ◽  
Author(s):  
Jan Novrocík ◽  
Marta Novrocíková ◽  
Miloš Titz
Keyword(s):  
Liquid Chromatography ◽  
Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbons ◽  
Gas Liquid Chromatography ◽  
Reaction Products ◽  
Aromatic Substrates ◽  
Alkyl Groups ◽  
Phenyl Rings ◽  
Separation Of Mixtures ◽  
Analytical Standards

Trimethyl- and methylethylbiphenyls with the alkyl groups in the both phenyl rings have been prepared by the Gomberg reaction and identified by the capillary gas-liquid chromatography. Depending on choice of the aromatic hydrocarbon either individual isomers or their mixtures (three at the most) have been obtained which were contaminated with compounds of diarylmethane type in many cases. The methylethylbiphenyls have only been prepared as mixtures contaminated with diarylmethanes. These side products have been prepared by independent syntheses. A method has been developed for isolation and separation of mixtures of trimethyl- and methylethylbiphenyls from the reaction products containing tarry products. The method is suitable for preparation of small amounts of some analytical standards. The HMO method has been used for calculation of values of the radical superdelocalizabilities at individual centres in the molecules of o-, m- and p-xylene, toluene and ethylbenzene, and these values have been compared with composition of the Gomberg reaction products from these hydrocarbons. The competitive technique has been used for comparison of the reactivities of the mentioned aromatic substrates in the Gomberg reactions.

The bromination of some N,N-dimethylanilines with dibromoisocyanuric acid

1977 ◽  
Vol 30 (7) ◽  
pp. 1561 ◽  
Author(s):  
J Rosevear ◽  
JFK Wilshire
Keyword(s):  
Liquid Chromatography ◽  
Quantitative Analysis ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Gas Liquid Chromatography ◽  
Reaction Products ◽  
Solvent Shift ◽  
Solvent Shifts ◽  
Dibromoisocyanuric Acid

The reaction of some representative N,N-dimethylanilines with dibromoisocyanuric acid has been investigated. In many cases, mixtures of brominated products were obtained; these mixtures were analysed both by gas-liquid chromatography and by proton magnetic resonance spectroscopy. With excess of reagent, perbromination was readily achieved. ��� Significant solvent shifts [δ(CDCl3)-δ(C6D6)] were observed for a wide variety of bromo-N,N-dimethylanilines. This solvent shift phenomenon was used not only for the assignment of structure to reaction products but also for the quantitative analysis of mixtures of bromo-N,N-dimethylanilines.

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