Side chain nitration of polymethylbenzenes in nitric acid-acetic anhydride mixtures

1973 ◽  
Vol 26 (4) ◽  
pp. 775 ◽  
Author(s):  
DJ Blackstock ◽  
A Fischer ◽  
KE Richards ◽  
GJ Wright
Keyword(s):  
Gas Chromatography ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Side Chain ◽  
Methyl Group ◽  
Product Distributions

Product distributions resulting from nitration of polymethylbenzenes in nitric acid-acetic anhydride mixtures have been determined by gas chromatography. Nitration of a methyl group occurs in all the substrates studied; such nitration occurs only at a methyl group para to the methyl most activated to ipso nitration. These results support the view that side chain nitration occurs through the diene intermediates which lead to ring acetoxylation.

scholarly journals Nitration of the tetramethylbenzenes in acetic anhydride. Formation and rearomatization of adducts

1976 ◽  
Vol 54 (11) ◽  
pp. 1795-1806 ◽  
Author(s):  
Alfred Fischer ◽  
David R. A. Leonard
Keyword(s):  
Acetic Anhydride ◽  
Side Chain ◽  
Methyl Group ◽  
Nitro Derivatives

Nitration of the tetramethylbenzenes in acetic anhydride at temperatures below –50 °C gives the l-acetoxy-4-nitro and 5-acetoxy-2-nitro adducts from the 1,2,3,4 isomer, the 5-acetoxy-2-nitro adduct from the 1,2,3,5 isomer, and the l-acetoxy-4-nitro adduct from the 1,2,4,5 isomer as well as the expected nitro derivatives. Corresponding nitritonitro adducts are also formed as well as side-chain (benzylic) derivatives: nitrates and phenylnitromethanes. Rearomatization of the tertiary acetate adducts leads to aryl acetates, benzylic derivatives, or nitroarenes, depending upon the acidity of the solvent. In the benzylic derivatives the methyl group substituted is that ipso to the acetate in the precursor adduct, that para to the most activated ipso position of the arene.

Adduct Intermediates in the Side-chain Nitration of 1,4-Dimethylnaphthalene

1972 ◽  
Vol 50 (24) ◽  
pp. 3988-3992 ◽  
Author(s):  
Alfred Fischer ◽  
Alan Leslie Wilkinson
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Room Temperature ◽  
Methylene Chloride ◽  
Side Chain ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Naphthyl Acetate

cis and trans isomers of 1,4-dimethyl-4-nitro-1,4-dihydro-1-naphthyl acetate (1) have been isolated from a mixture of 1,4-dimethylnaphthalene and nitric acid in acetic anhydride by quenching at −40°. At room temperature only 1-methyl-4-nitromethylnaphthalene (4) is obtained. The conversion of 1,4-dimethylnaphthalene to 4 and of the cis (1a) and trans (1b) adducts to 4, by nitric acid in acetic anhydride, has been followed by n.m.r. 1,4-Dimethyl-4-nitro-1,4-dihydro-1-naphthyl nitrate (5) appears to be the immediate product from nitration of 1,4-dimethylnaphthalene in acetic anhydride, methylene chloride, or nitromethane. In acetic anhydride 5 is converted into 1. Decomposition of 1 in acetic acid gives 1,4-dimethyl-2-naphthyl acetate and some 4. The formation of 4 in this reaction is suppressed by urea.

scholarly journals Effect of side-chain length in lignin model compound on MnO2 oxidation: comparison of oxidations between C6-C2- and C6-C1-type compounds

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Shirong Sun ◽  
Tomoya Yokoyama
Keyword(s):  
Isotope Effects ◽  
Aromatic Nucleus ◽  
Side Chain ◽  
Direct Oxidation ◽  
Initial Oxidation ◽  
Methyl Group ◽  
Lignin Model Compound ◽  
Oxidation Rates ◽  
Kinetic Isotope ◽  
Lignin Model

AbstractMonomeric C6-C2-type lignin model compounds with a p-hydroxyphenyl (H), guaiacyl (G), syringyl (S), or p-ethylphenyl (E) nucleus (1-phenylethanol derivatives) were individually oxidized by MnO2 at a pH of 1.5 and room temperature. The results were compared with those of the corresponding C6-C1-type benzyl alcohol derivatives obtained in our recent report to examine the effect of the presence of the β-methyl group on the oxidation. The presence decelerated the oxidation regardless of the type of aromatic nucleus, although it did not change the order of the oxidation rates: G > S >> H > E. This deceleration results from the steric factor of the β-methyl group in the C6-C2-type compounds. The MnO2 oxidations of the corresponding C6-C2-type compounds deuterated at their α-(benzyl)positions showed that the magnitudes of the kinetic isotope effects are smaller than those observed in the oxidations of the corresponding C6-C1-type compounds, regardless of the type of aromatic nucleus. These smaller magnitudes suggest that the presence of the β-methyl group shifts the initial oxidation mode of MnO2 from direct oxidation of the benzyl position to one-electron oxidation of the aromatic nucleus. Only the S-type compounds afforded products via degradation of the aromatic nuclei.

Chemistry of Fenchonesulfonic Acid Derivatives

1995 ◽  
Vol 50 (2) ◽  
pp. 283-288 ◽  
Author(s):  
Gabriele Wagner ◽  
Uwe Verfürth ◽  
Rudolf Herrmann
Keyword(s):  
Acetic Anhydride ◽  
Thionyl Chloride ◽  
Sulfonic Acid ◽  
Reaction Rate ◽  
Enantiomeric Excess ◽  
Methyl Group ◽  
Close Analogy ◽  
Chiral Sulfoxides ◽  
Mndo Calculations ◽  
Nmr Techniques

(1 S) - (+)-Fenchone is sulfonated by SO3 or H2SO4/acetic anhydride in the bridgehead methyl group. This could be confirmed by NMR techniques (INADEQUATE). The fenchonesulfonic acid obtained is converted (SOCl2/NH3) to the cyclic fenchonesulfonimide, which can be oxidized to the corresponding oxaziridine, in close analogy to 10-camphorsulfonimide. Improved procedures for this reaction sequences are given. During the treatment of the sulfonic acid with thionyl chloride, a byproduct with a rearranged bicyclic skeleton is observed whose structure has been determined by ozonolytic degradation and NMR techniques. A possible mechanism for this rearrangement is suggested, based on MNDO calculations of the intermediate carbocations. The fenchonesulfonyloxaziridine oxidizes sulfides to chiral sulfoxides with appreciable enantiomeric excess, but very low reaction rate. A comparison with camphor-derived oxaziridines having similar steric requirements is made.

The Rates and Products of Addition of 4-Chlorobenzenesulfenyl Chloride to a Series of Side Chain Methyl Substituted Styrenes

1974 ◽  
Vol 52 (9) ◽  
pp. 1807-1812 ◽  
Author(s):  
George H. Schmid ◽  
Dennis G. Garratt
Keyword(s):  
Steric Hindrance ◽  
Side Chain ◽  
Methyl Groups ◽  
Methyl Group

The rates of addition and the product compositions have been determined for the addition of 4-chlorobenzenesulfenyl chloride to a series of seven side chain methyl substituted styrenes in 1,1,2,2-tetrachloroethane at 25°. Unlike the addition to the corresponding series of methylated ethylenes, the effect of the methyl groups is not cumulative. The effect of the methyl groups depends upon whether or not the β-methyl group is cis to the phenyl. When it is cis, the rate of addition is decreased compared to styrene and substitution of additional methyl groups has only a small effect on the rate of addition. In compounds lacking a cis-β-methyl group the rate of addition more closely resembles that for addition to the methylated ethylenes. Steric hindrance between the cis-methyl and phenyl groups is believed to be the cause of this difference in behavior between the ethylene and styrene series.

Synthesis of Side-Chain Locked Analogs of 1α,25-Dihydroxyvitamin D3 Bearing a C17 Methyl Group

2018 ◽  
Vol 20 (9) ◽  
pp. 2641-2644 ◽  
Author(s):  
Rita Sigüeiro ◽  
Miguel A. Maestro ◽  
Antonio Mouriño
Keyword(s):  
Side Chain ◽  
Dihydroxyvitamin D3 ◽  
Methyl Group

Efficient extraction of basic, neutral, and weakly acidic drugs from plasma for analysis by gas chromatography-mass spectrometry

1991 ◽  
Vol 37 (11) ◽  
pp. 1975-1978 ◽  
Author(s):  
K E Brooks ◽  
N B Smith
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Acetic Anhydride ◽  
Mobile Phase ◽  
Plasma Sample ◽  
Gas Chromatography Mass Spectrometry ◽  
Acidic Drugs ◽  
Chromatography Mass Spectrometry ◽  
Efficient Extraction ◽  
Layer Chromatography

Abstract We describe a method for efficiently extracting basic, neutral, and weakly acidic drugs from plasma for toxicological analysis by gas chromatography-mass spectrometry (GC/MS). The 2-mL plasma sample is diluted with an equal volume of saturated NaCl containing triethylamine, 10 mmol/L, and then extracted twice with 4 mL of an equivolume solution of dichloromethane/acetone. The organic (top) phases are combined, then mixed with 1 mL of water, 200 mg of NaHCO3, and 100 microliters of acetic anhydride. This mixture is then heated at 75 degrees C until the solvents have boiled off and aqueous acetylation is complete (less than 30 min). After addition of 1 mL of water and 2 g of NaCl, the sample is extracted twice with 2 mL of dichloromethane/acetone (2/1 by vol). The combined extracts are dried and then subjected to thin-layer chromatography on a blank Toxi-Lab Toxi-A chromatogram with 1-chlorobutane as the developing solvent (about 6 min). After the lipids have migrated with the mobile phase, the drugs are eluted from the origin with acetone/triethylamine (29/1 by vol), evaporated, and reconstituted in injection solvent. With this procedure drugs are recovered relatively quickly (less than 2 h) and the GC/MS total ion chromatograms are very clean. Studies with 13 basic, neutral, and weakly acidic drugs showed that all except theophylline were extracted with recoveries of at least 75%.

scholarly journals Unusual Regularity in GC Retention of Simple Amino Acid Derivatives

2019 ◽  
Vol 6 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Igor G. Zenkevich ◽  
Nino G. Todua ◽  
Anzor I. Mikaia
Keyword(s):  
Gas Chromatography ◽  
Retention Index ◽  
Methyl Esters ◽  
Elution Order ◽  
Alkyl Esters ◽  
Methyl Group ◽  
The Difference ◽  
Direct Use ◽  
Derivatives Of

Background: Application of simple regularities and general principles along with direct use of reference gas chromatography retention index data for reliable structure determination of compounds can be enhanced by determination of new regularities that are specific to certain structural elements. Objective: Revelation and interpretation of an anomaly in the elution order of alkyl esters of alkoxycarbonyl derivatives of glycine and alanine on standard and semi-standard non-polar phases. Method: Preliminary derivatization of amino acids to alkyl esters of N-alkoxycarbonyl analogs and interpretation of their gas chromatographic characteristics. Results: Alkyl esters of N-alkoxycarbonyl derivatives of alanine (Alkyl = C2H5, n- and iso-C3H7) elute prior to the same derivatives of glycine, despite the presence of an additional methyl group at C(2) in the molecule. Elution order is reversed for methyl esters of N-methoxycarbonyl derivatives. Conclusion: It is established that the peculiar behavior of alkyl esters of N-alkoxycarbonyl derivatives of glycine and alanine agrees with the concepts of gas chromatography and the known retention index regularities of organic compounds. A decrease of retention index values is a result of an introduction of an additional methyl group to a carbon atom connected to two polar fragments in a molecule like CH2XY. The dependence of the difference of retention index values for homologs of the types of CH3-CHXY and CH2XY vs. the total mass of fragments (X + Y) is similar to those for other sub-groups of analytes.

Selective Nitroxylation of Adamantane Derivatives in the System Nitric Acid–Acetic Anhydride

2020 ◽  
Vol 56 (9) ◽  
pp. 1532-1539
Author(s):  
Yu. N. Klimochkin ◽  
E. A. Ivleva ◽  
I. K. Moiseev
Keyword(s):  
Nitric Acid ◽  
Acetic Anhydride ◽  
Adamantane Derivatives
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