Synthesis and Identification of ω-Phenylalkylcatechols in Burmese Lac

1988 ◽  
Vol 41 (1) ◽  
pp. 19 ◽  
Author(s):  
A Jefferson ◽  
MV Sargent ◽  
S Wangchareontrakul
Keyword(s):  
Natural Products ◽  
Catalytic Hydrogenation ◽  
Wittig Reaction ◽  
Spectral Characteristics ◽  
Chromatographic Retention ◽  
Phosphonium Bromide ◽  
Mass Spectral ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

The presence of 3-(10′-phenyldecyl)-(2) (2%), 3-(12′-phenyldodecyl)- (3) (6%), 4-(10′-phenyldecyl)-(4) (0.3%) and 4-(12′-phenyldodecyl)- benzene-1,2-diol (5) (0.3%) in Burmese lac , the sap of Melanorrhoea usitata Wall has been confirmed by the synthesis of these compounds and a comparison of the gas chromatographic retention times and the mass spectral characteristics of their bis-O-( trimethylsilyl ) derivatives with the derivatives of the natural products. Typically, 3,4- bis ( benzyloxy ) benzaldehyde (7) on Wittig reaction with triphenyl (11- phenylundecyl ) phosphonium bromide (20) and subsequent catalytic hydrogenation of the resultant olefin gave compound (5) in 59% overall yield.

Massenspektrometrische Fragmentierung von Trimethylsilylderivaten (TMS) des Thyrotropin-„Releasing“-Hormons (TRH) und dessen Teilstrukturen / Mass Spectroscopy of Trimethylsilyl Derivatives of Thyrotropin-releasing Hormone and its Constituents

1973 ◽  
Vol 28 (11-12) ◽  
pp. 820-823 ◽  
Author(s):  
W. A. König ◽  
S. Fuchs ◽  
K. Zech ◽  
W. Voelter
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectroscopy ◽  
Peptide Hormones ◽  
Thyrotropin Releasing Hormone ◽  
Mass Spectral Fragmentation ◽  
Releasing Hormone ◽  
Mass Spectral ◽  
Trimethylsilyl Derivatives ◽  
Fragmentation Patterns ◽  
Derivatives Of

The mass spectral fragmentation patterns of trimethylsilyl derivatives of TRH and its constituents are discussed. The utility of these derivatives for the control of the synthesis of peptide hormones by mass spectrometry is obvious.

The N-alkylation of some barbiturates and other acidic drugs

1976 ◽  
Vol 29 (8) ◽  
pp. 1769 ◽  
Author(s):  
S Dilli ◽  
DN Pillai
Keyword(s):  
Anticonvulsant Drugs ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Mass Spectral ◽  
Acidic Drugs ◽  
Derivatives Of

The synthesis of a number of new N,N'-dialkyl barbituric acids is reported. The compounds are ethyl hexobarbital, the diethyl derivatives of secobarbital and cyclobarbital, the chloroethyl derivatives ofmephobarbital and hexobarbital, and the bis(chloroethy1) derivatives of barbital, cyclobarbital, secobarbital, butobarbital and secbutobarbital.In addition, several new N-alkylated derivatives of some common anticonvulsant drugs are included. These are ethyl glutethimide, the chloroethyl derivatives of ethosuximide, glutethimide, peganone, mephenytoin and diphenylhydantoin. Infrared, N.M.R., mass spectral and gas chromatographic retention data are given.

Microwave-induced rapid preparation of fluoro-derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine for GC-MS confirmation assays

1994 ◽  
Vol 40 (9) ◽  
pp. 1703-1706 ◽  
Author(s):  
W C Thompson ◽  
A Dasgupta
Keyword(s):  
Microwave Irradiation ◽  
Conventional Technique ◽  
Conventional Heating ◽  
Chromatographic Retention ◽  
Rapid Preparation ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
Derivatives Of ◽  
Fluoro Derivatives

Abstract We prepared trifluoroacetyl, pentafluoropropyl, and heptafluorobutyl derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in 45 s, 1 min, and 6 min, respectively, by using microwave irradiation. Conventional techniques require heating the reaction mixture for 15 min at 40 degrees C for trifluoroacetyl derivatives, 15 min at 75 degrees C for pentafluoropropyl derivatives, and 40 min at 60 degrees C for heptafluorobutyl derivatives. The mass-spectral fragmentation patterns and the gas-chromatographic retention times of the derivatives obtained by both microwave irradiation and conventional heating were similar. Perfluorooctanoyl derivatives of amphetamine can be prepared quantitatively by either heating the reaction mixture for 30 min at 60 degrees C or by 1 min of microwave irradiation. Conversion of methamphetamine and MDMA to the corresponding perfluorooctanoyl derivatives was not quantitative by either technique, although the yield of the derivative in the conventional technique was much higher.

ChemInform Abstract: TRIMETHYLSILYL DERIVATIVES OF TITANIUM

1978 ◽  
Vol 9 (19) ◽  
Author(s):  
G. A. RAZUVAEV ◽  
V. N. LATYAEVA ◽  
L. I. VYSHINSKAYA ◽  
A. V. MALYSHEVA ◽  
G. A. VASI'EVA
Keyword(s):  
Trimethylsilyl Derivatives ◽  
Derivatives Of

A State-Space Approach to the Synthesis of Random Vertical and Crosslevel Rail Irregularities

1990 ◽  
Vol 112 (1) ◽  
pp. 83-87 ◽  
Author(s):  
R. H. Fries ◽  
B. M. Coffey
Keyword(s):  
Numerical Simulation ◽  
White Noise ◽  
State Space ◽  
Spectral Characteristics ◽  
The State ◽  
Second Derivatives ◽  
Time Histories ◽  
Sample Interval ◽  
Rail Irregularities ◽  
Derivatives Of

Solution of rail vehicle dynamics models by means of numerical simulation has become more prevalent and more sophisticated in recent years. At the same time, analysts and designers are increasingly interested in the response of vehicles to random rail irregularities. The work described in this paper provides a convenient method to generate random vertical and crosslevel irregularities when their time histories are required as inputs to a numerical simulation. The solution begins with mathematical models of vertical and crosslevel power spectral densities (PSDs) representing PSDs of track classes 4, 5, and 6. The method implements state-space models of shape filters whose frequency response magnitude squared matches the desired PSDs. The shape filters give time histories possessing the proper spectral content when driven by white noise inputs. The state equations are solved directly under the assumption that the white noise inputs are constant between time steps. Thus, the state transition matrix and the forcing matrix are obtained in closed form. Some simulations require not only vertical and crosslevel alignments, but also the first and occasionally the second derivatives of these signals. To accommodate these requirements, the first and second derivatives of the signals are also generated. The responses of the random vertical and crosslevel generators depend upon vehicle speed, sample interval, and track class. They possess the desired PSDs over wide ranges of speed and sample interval. The paper includes a comparison between synthetic and measured spectral characteristics of class 4 track. The agreement is very good.

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