scholarly journals THE STEREOCHEMISTRY OF HALOGEN DISPLACEMENT BY NITRATE ION RACEMIZATION AND RETENTION OF CONFIGURATION IN THE SYNTHESIS OF DINITRATE ESTERS

1965 ◽  
Vol 43 (6) ◽  
pp. 1656-1660 ◽  
Author(s):  
L. D. Hayward ◽  
M. Jackson ◽  
I. G. Csizmadia
Keyword(s):  
Silver Nitrate ◽  
Steric Effect ◽  
Heterogeneous Reaction ◽  
Ion Pair ◽  
Alkyl Halides ◽  
Preferential Formation ◽  
Carbonium Ion ◽  
Carbonium Ions ◽  
And Inversion ◽  
Derivatives Of

The reaction of silver nitrate in dry acetonitrile with 2,5-dideoxy-2,5-diiodo-1,4;3,6-dianhydro-L-iditol resulted in formation of the dinitrate esters of the 1,4;3,6-dianhydrides of D-mannitol, D-glucitol, and L-iditol. Similarly both endo- and exo-nitrato groups were introduced in displacement of the endo-halogen in the 2-deoxy-2-iodo-5-O-acetyl and 2-deoxy-2-iodo-5-O-p-toluenesulfonyl derivatives of 1,4;3,6-dianhydro-L-iditol. Since both types of nitrato groups were stable to silver nitrate, the racemization occurred during the displacement and was attributed to formation of cyclic carbonium ion intermediates. The steric effect of the adjacent ring in the carbonium ions apparently suppressed the termolecular, ion-pair mechanism previously established for the metathesis of acyclic alkyl halides and caused preferential formation of the exo-nitrato derivatives.The heterogeneous reaction of meso-dibromostilbene with silver nitrate in acetic acid or acetonitrile gave meso-dihydrobenzoin dinitrate with overall retention of configuration. This result could be most readily reconciled with the contrasting sequence of retention and inversion previously reported for meso- and dl-2,3-dibromobutane if participation of neighboring phenyl groups occurred in the second displacement step.

Synthesis of 5H-dibenzo[a,d]cycloheptene-5-carboxylic acid and related compounds. 1,5-Hydride transfer to inductively destabilized carbonium ions

1968 ◽  
Vol 46 (23) ◽  
pp. 3665-3670 ◽  
Author(s):  
D. E. Horning ◽  
J. M. Muchowski
Keyword(s):  
Carboxylic Acid ◽  
Carbonyl Group ◽  
Isotope Effect ◽  
Hydride Transfer ◽  
Large Magnitude ◽  
Carbonium Ion ◽  
Carbonium Ions ◽  
Acid Catalyzed ◽  
Derivatives Of ◽  
Related Compounds

The synthesis of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene-5-carboxylic acid (2) and several derivatives of 5H-dibenzo[a,d]cycloheptene-5-carboxylic acid (1; a–c) from 5-hydroxy-10,11-dihydro-5H-dibenzo[a,d]cycloheptene-5-carboxylic acid and derivatives thereof (3; a–c) is described.The p-toluenesulfonic acid-catalyzed elimination of water (at 110.6° in toluene) from the deuterated hydroxy ester (3b; C-10, 11 d2) resulted in the incorporation of deuterium at C-5 of the olefinic ester 1b with a KH/KD of 2.76. The large magnitude of this isotope effect indicated that the reaction proceeded via a rate-determining transannular 1,5-hydride transfer from one of the benzylic positions of 3b to the carbonium ion generated alpha to the methoxy-carbonyl group.

scholarly journals CHEMISTRY AND SYNTHESIS OF SOME DIHYDRO-2H-l,4-BENZOTHIAZINE DERIVATIVES

1966 ◽  
Vol 44 (11) ◽  
pp. 1247-1258 ◽  
Author(s):  
Raj Nandan Prasad ◽  
Karin Tietje
Keyword(s):  
Alkyl Halides ◽  
Reduction Product ◽  
Alkyl Derivatives ◽  
Reaction Proceeds ◽  
Thiazine Ring ◽  
Derivatives Of ◽  
Compound Xviii ◽  
Acyl Derivatives

The formation of 3-oxo-3,4-dihydro-2H-1,4-benzothiazine (IIIa) by cyclization of alkyl 2-haloacetamidophenyl sulfides (I) was investigated; it is proposed that the reaction proceeds via a six-membered sulfonium halide. The preparation of 4-alkyl derivatives of IIIa and of 4-alkyl and 4-acyl derivatives of its reduction product 3,4-dihydro-2H-1,4-benzothiazine (Va) is described. Acylation of Va was shown to proceed without opening of the thiazine ring. Preparation of the O-benzoyl, N-benzoyl, and O,N-dibenzoyl derivatives of 2-(β-hydroxyethyl-mercapto)aniline (VIII) has permitted clarification of the confusion in the literature with respect to the derivatives of Va and VIII. Compound XVIII, the 1,1-dioxide of IIIa, undergoes C-alkylation at the 2-position when treated with alkyl halides, rather than O-alkylation as previously suggested.

Hydrazine derivatives. III. A study of alkylation of guanazole

1976 ◽  
Vol 54 (22) ◽  
pp. 3620-3625 ◽  
Author(s):  
José J. Fuentes ◽  
Jacques A. Lenoir
Keyword(s):  
Aqueous Media ◽  
Alkyl Halides ◽  
Hydrazine Derivatives ◽  
Derivatives Of

Spectroscopic results from mono- and dibenzylidene derivatives of 1-alkylguanazoles establish that alkylation of 3,5-diamino-1,2,4-triazole (guanazole) with alkyl halides in basic non-aqueous media occurs at position N-1.

Notizen: The Synthesis of a New Fused Thiazolo [4,3-c] -1,2,4-triazole System and its Derivatives

1976 ◽  
Vol 31 (6) ◽  
pp. 853-856 ◽  
Author(s):  
Nazmi Abd Elatif Kassab ◽  
Sanaa Osman Abd Allah ◽  
Hamed Abdel Reheem Ead
Keyword(s):  
Potassium Salt ◽  
Aromatic Aldehydes ◽  
Alkyl Halides ◽  
Formaldehyde Solution ◽  
Derivatives Of

Cyclisation of the 4-phenylhydrazono derivatives of 2-thiazolidinone or 2-thiazolidinethione (1) with formaldehyde solution or with aromatic aldehydes yields 2-phenyl-2,3-dihydrothiazolo[4,3-c]-1,2,4-triazol-5-one or its 5-thiocarbonyl analogue (2). Condensing 2 with aromatic aldehydes afforded the corresponding 7-arylidene derivatives (8).The 5-arylidene derivatives of 4-anisylimino-2-thiazolidinethione (5) were obtained by condensing 4 with aromatic aldehydes. The potassium salt of 5 reacts readily with alkyl halides to yield the 5-arylidene derivatives of 4-anisylimino-2-alkylmercapto-2-thiazoline (6).

The Ion Associates of Methyl-, Ethyl- and Isopropyl Derivatives of Dialkylaminoethyl Dialkylamidofluorophosphate with Bromophenol Blue

1992 ◽  
Vol 57 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Emil Halámek ◽  
Zbyněk Kobliha
Keyword(s):  
Extraction Efficiency ◽  
Ion Pairs ◽  
Amino Nitrogen ◽  
Ion Pair ◽  
Amide Group ◽  
Bromophenol Blue ◽  
Amino Group ◽  
Methyl Ethyl ◽  
Derivatives Of

Nine new Tammelin esters were studied on the basis of the chloroform extracts of their ion associates with bromophenol blue. A study was made of the effect of the alkyl on the amino and amido groups of dialkylaminoethyl dialkylamidofluorophosphate and on the extraction efficiency of the ion pair. An increase in the number of carbon atoms on the amide group leads to the increase in the extraction efficiency of the ion pairs as a consequence of the increasing hydrophobicity. A further contribution to the increase in the extraction efficiency with increasing number of carbon atoms in the alkyls of the amino nitrogen is clearly retarded by the increasing basicity of the amino group. An extraction spectrophotometric determination of the test derivatives of dialkylaminoethyl dialkylamidofluorophosphate was developed and the interferences from precursors in the synthesis were examined.

The radiation-induced polymerization of iso butene

1959 ◽  
Vol 252 (1269) ◽  
pp. 187-196 ◽  
Keyword(s):  
Low Temperatures ◽  
High Energy ◽  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Propagation Mechanism ◽  
Fractional Conversion ◽  
High Energy Radiation ◽  
Carbonium Ion ◽  
Carbonium Ions ◽  
Radiation Induced

Iso butene polymerizes at low temperatures when exposed to high-energy radiation. The resulting polymer, of high molecular weight, is similar in all respects to normal poly iso butene. The fractional conversion of monomer per unit radiation dose is independent of the intensity of radiation and increases as the temperature is lowered. The polymerization is inhibited by di- iso butene which also inhibits the normal ionic polymerization and by both oxygen and benzoquinone which normally inhibit free radical polymerization but not ionic polymerizations. Carbon tetrachloride has little effect on the rate of the radiation-induced polymeriza­tion or on the average degree of polymerization of the product. The reaction is very sensitive to surface and may be in part intrinsically heterogeneous. All the evidence points to a carbonium ion propagation mechanism for the propagation of polymer chains which may be initiated either by primary ion-radicals formed from iso butene or by carbonium ions formed on disruption of the ion-radicals.

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