Hexamethylazoxybenzene. Structure, Basicity, and Rearrangement

1973 ◽  
Vol 51 (18) ◽  
pp. 3143-3149 ◽  
Author(s):  
Robin A. Cox ◽  
Erwin Buncel
Keyword(s):  
Sulfuric Acid ◽  
Steric Hindrance ◽  
Reaction Mechanisms ◽  
Electronic Effect ◽  
Two Factors ◽  
Large Distortion ◽  
Concentrated Sulfuric Acid ◽  
Steric Inhibition Of Resonance

2,2′,4,4′,6,6′-Hexamethylazoxybenzene (1) has been prepared and characterized. The u.v. spectrum is indicative of large distortion from coplanarity. 1 is only slightly more basic than azoxybenzene despite expectations due to electronic effect of the methyl substituents. Two factors are considered responsible for this: steric inhibition of resonance in the unprotonated species and steric hindrance to hydration in the conjugate acid.Rearrangement of 1 in moderately concentrated sulfuric acid gives rise to the alcohol 4-hydroxymethyl-2,2′,4′,6,6′-pentamethylazobenzene (6). A Bamberger type phenolic product which would result from methyl migration is not observed. Possible reaction mechanisms are given.

Gallium Arsenide Integrated Circuits Decapsulation Technique Using Mixed Acid Chemistry For Die-Level Failure Analysis

2018 ◽  
Author(s):  
Harold Jeffrey M. Consigo ◽  
Ricardo S. Calanog ◽  
Melissa O. Caseria
Keyword(s):  
Gallium Arsenide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
Mixed Acid ◽  
Optimum Parameters ◽  
Plastic Package ◽  
Fuming Nitric Acid ◽  
Concentrated Sulfuric Acid

Abstract Gallium Arsenide (GaAs) integrated circuits have become popular these days with superior speed/power products that permit the development of systems that otherwise would have made it impossible or impractical to construct using silicon semiconductors. However, failure analysis remains to be very challenging as GaAs material is easily dissolved when it is reacted with fuming nitric acid used during standard decapsulation process. By utilizing enhanced chemical decapsulation technique with mixture of fuming nitric acid and concentrated sulfuric acid at a low temperature backed with statistical analysis, successful plastic package decapsulation happens to be reproducible mainly for die level failure analysis purposes. The paper aims to develop a chemical decapsulation process with optimum parameters needed to successfully decapsulate plastic molded GaAs integrated circuits for die level failure analysis.

PRODUCTION OF SULFOCATIONITE BY MODIFICATION OF NATURAL COAL WITH CONCENTRATED SULFURIC ACID

2020 ◽  
Vol 3 (441) ◽  
pp. 104-109
Author(s):  
N.A. Bektenov ◽  
◽  
N.C. Murzakassymova ◽  
M.A. Gavrilenko ◽  
А.N. Nurlybayeva ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Concentrated Sulfuric Acid ◽  
Natural Coal

Addition of primary alcohols to 3-chlorononafluoro-1,5-hexadiene and perfluoro-1,3,5-hexatriene

1985 ◽  
Vol 50 (8) ◽  
pp. 1714-1726 ◽  
Author(s):  
Václav Dědek ◽  
Igor Linhart ◽  
Milan Kováč
Keyword(s):  
Sulfuric Acid ◽  
Primary Alcohols ◽  
Principal Product ◽  
Allyl Rearrangement ◽  
Concentrated Sulfuric Acid ◽  
Sodium Alkoxide

Sodium alkoxide-catalyzed addition of methanol, ethanol and propanol to 3-chlorononafluoro-1,5-hexadiene (I) proceeds at temperatures -35 °C to 8 °C with allyl rearrangement, affording 1,6-dialkoxy-1,1,2,3,4,4,5,6,6-octafluoro-2,4-hexadiene (V) as the principal product, along with 1,6-dialkoxy-1,2,3,3,4,5,6,6-octafluoro-1,5-diene (VI) and trans-1,6-dialkoxy-1,1,2,3,4,4,5,6,6-nonafluoro-2-hexene (VII). The ethers Va-Vc consist of the cis,trans- and trans,trans-isomers in about 3 : 1 ratio, whereas the ethers VIa-VIc have trans,trans-configuration. Ethers Vc and VIc react with concentrated sulfuric acid to give dipropyl 2,3,4,5-tetrafluoro-2,4-hexadienedioate (IX) and dipropyl 2,3,4,4,5-pentafluoro-2-hexenedioate (X), respectively, whereas the ether VIIc affords a mixture of propyl 6-propyloxy-2,3,4,4,5,6-heptafluoro-2-hexenoate (XI) and ester X. Addition of methanol to perfluoro-1,3,5-hexatriene (II) affords 1,1,2,3,4,5,6,6-octafluoro-1,6-dimethoxy-3-hexene (XIII) as the principal product.

scholarly journals 4,5,6-Trichloropyrimidine-2-carboxamide

Molbank ◽  
10.3390/m1190 ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. M1190
Author(s):  
Andreas S. Kalogirou ◽  
Panayiotis A. Koutentis
Keyword(s):  
Sulfuric Acid ◽  
Elemental Analysis ◽  
Maldi Tof ◽  
Concentrated Sulfuric Acid

Reaction of 4,5,6-trichloropyrimidine-2-carbonitrile (1) with concentrated sulfuric acid at ca. 20 °C gave 4,5,6-trichloropyrimidine-2-carboxamide (5) in 91% yield. The new compound was fully characterized by IR, MALDI-TOF, NMR and elemental analysis.

Regioselective Bromination of Anilines in the Presence of Nitrosonium Hydrogensulfate in Concentrated Sulfuric Acid

1995 ◽  
Vol 5 (2) ◽  
pp. 65-66 ◽  
Author(s):  
Mikhail V. Gorelik ◽  
Vera I. Lomzakova ◽  
Elena A. Khamidova ◽  
Vitalii Ya. Shteiman ◽  
Marianna G. Kuznetsova ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Concentrated Sulfuric Acid

ChemInform Abstract: The Corrosion Behavior of Amorphous Fe-8Cr-13P-7C and Fe-8Cr-20P Alloys in Concentrated Sulfuric Acid.

ChemInform ◽  
2010 ◽  
Vol 25 (49) ◽  
pp. no-no
Author(s):  
B.-M. IM ◽  
E. AKIYAMA ◽  
H. HABAZAKI ◽  
A. KAWASHIMA ◽  
K. ASAMI ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Corrosion Behavior ◽  
Concentrated Sulfuric Acid

scholarly journals Highly Porous Carbon Materials from Biomass by Chemical and Carbonization Method: A Comparison Study

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Wan Nor Roslam Wan Isahak ◽  
Mohamed Wahab Mahamed Hisham ◽  
Mohd Ambar Yarmo
Keyword(s):  
Sulfuric Acid ◽  
Thermal Behavior ◽  
Surface Area ◽  
Porous Carbon ◽  
High Surface ◽  
High Surface Area ◽  
Empty Fruit Bunches ◽  
Heating Treatment ◽  
Concentrated Sulfuric Acid ◽  
Highly Porous

Porous carbon obtained by dehydrating agent, concentrated sulfuric acid (H2SO4), from biomass containing high cellulose (filter paper (FP), bamboo waste, and empty fruit bunches (EFB)) shows very high surface area and better thermal behavior. At room temperature (without heating), treatment of H2SO4removed all the water molecules in the biomass and left the porous carbon without emitting any gaseous byproducts. Brunauer-Emmett-Teller (BET) surface analysis has shown that bamboo-based carbon has good properties with higher surface area (507.8 m2/g), micropore area (393.3 m2/g), and better thermal behavior (compared to FP and EFB) without any activation or treatment process. By acid treatment of biomass, it was shown that higher carbon composition obtained from FP (85.30%), bamboo (77.72%), and EFB (76.55%) is compared to carbon from carbonization process. Under optimal sulfuric acid (20 wt.%) uses, high carbon yield has been achieved for FP (47.85 wt.%), bamboo (62.4 wt.%), and EFB (55.4 wt.%).

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