Details of elemental analyzes and description of instruments/equipment used for compound characterization and structural evaluation. Techniques involved in the structural evaluation of newly synthesized compounds were mentioned, including bromination reagents and brominated organocompounds.
An environmentally friendly biomimetic synthetic methodology for bromination of organic substrates by
In order to gain knowledge about the thermal behavior of the substance, thermogravimetric analysis (TGA) was carried out. The high to very high yields of most of the products obtained under mild reaction conditions with the other advantages mentioned above make the method a desirable alternative to traditional reagents and protocols for bromination.
An Acid assisted peroxo-molybdate(VI) catalyzed in situ bromination of organic substrates by
The results of this methodology are very similar to those of the previous methodology reported in chapter IV. One of the notable aspects of this methodology is that the product selectivity observed in the present case differs from that of earlier methodology.
The reaction times, ratio of substrates to catalyst, products and yields along with the results of the control reactions are summarized in Table 1. A comparison of the results of the catalytic reactions (Table 1) with those of uncatalyzed reactions clearly suggests that FeCl3 catalyzes the bromination reactions by TBATB.
CONTENT
Scheme 1
Scheme 1
LIST OF TABLES
Introduction and scope of the work
36 The present collaborator's attention was drawn to some highly selected aspects of the fluorine chemistry of copper(I) and manganese(III). Although the selected aspects of the fluorine metal chemistry of copper(I) and manganese(III) form a small but important part of the current Ph.
Brown in "The Chemistry of Vanadium, Niobium and Tantalum" Pergamon Press, Elmsford, NY, 1975; Pergamon Texts in Inorganic Chemistry, Vol. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, 5th Edition, 1997, John Wiley & Sons, Inc. Larock, Comprehensive Organic Transformations: A Guide to Functional Group Preparations, John Wiley & Sons, 2nd ed.; 1999, p.
Patnaik, A Comprehensive Guide to the Hazardous Properties of Chemical Substances, Van Nonstrand Reinhold, New York, 1992, p.
Details of elemental analysis and description of instruments/equipment used for characterization
MEASUREMENTS INFRARED SPECTRA
ELECTRONIC ABSORPTION SPECTRA
REFLECTANCE SPECTRUM
MAGNETIC SUSCEPTILBILITY MEASUREMENTS
THERMAL ANALYSIS
SOLUTION ELECTRICAL CONDUCTANCE MEASUREMENTS
CARBON, HYDROGEN AND NITROGEN MICROANALYSIS
1 H NMR SPECTROSCOPY
GC ANALYSIS
ELEMENTAL ANALYSES
Iodometry 2
To it was added 25 mL of water to obtain a colorless solution with a small amount of suspended oily mass (insoluble Ph3PO). This is filtered and 1 g of urea is added to the filtrate and the mixture is heated to boiling for 15 min. The solution is allowed to cool and to this is added 1 g of NaHCO3 until a permanent turbidity is observed.
The mixture was then kept in the dark for about 15 minutes and the amount of 12 released was titrated with standard sodium thiosulfate solution using starch as an indicator.
Gravimetric 3
To this was then added 3 ml of 10% NaCl solution, followed by 2 drops of bromophenol blue indicator. The PbClF was then dissolved in 100 ml of 5% HNO3 solution by boiling the solution for 30 minutes. For the estimation of fluoride from (NH 4 ) 3 [MnF 6 ], the compound was decomposed by treating a known amount of the compound with 100 ml of 5%.
A precisely weighed amount of the mixed iron(III) halo compound was dissolved in 25 ml of water in a slightly acidic state. A precisely weighed amount of the iron(III) compound was dissolved in 25 ml of water in a slightly acidic state. The neutral solution is acidified with 5 mL of 6 M HNO3 and an excess of 0.1 M AgNO3 solution is added to it.
An accurately weighed amount (0.1 g) of the tribromide was dissolved in 20 mL of CH 3 CN.
Some fluoro compounds of copper(I) and manganese(III): Synthesis of CuF(PPh 3 ) 3 .2ROH
CuF(PPh3)3.2ROH (R= Me or Et) as it is expected to find application in some synthetically useful transmetallation reactions.9. With the aforementioned considerations in mind, we attempted to synthesize CuF(PPh3)3.2ROH (R= Me or Et) to gain easy access to such compounds. It is relevant to note that the compound CuF(PPh3)3.2EtOH has been reported in the literature.
The crude product thus obtained was recrystallized twice from ethanol to give CuF(PPh3)3.2EtOH. Another concern of this study was to investigate the thermal properties of the compounds, as it was believed that such a study could provide a clue to the feasibility of obtaining "CuF" from such compounds. This part (Part A) of Chapter III presents the details of the study of CuF(PPh3)3.2ROH (R = Et or Me) including thermogravimetric analysis of CuF(PPh3)3.2MeOH.
A solution of copper(II) sulfate pentahydrate, CuSO4.5H2O, (3.0 g, 12 mmol) in water (50 mL) was treated with hydroxylamine hydrochloride, NH2OH.HCl, (0.83 g, 12 mmol), and to the resulting solution was added 10% NaOH solution slowly dropwise with constant stirring until the orange-red precipitate of copper(I) oxide, Cu2O, ceased to appear.
Results and discussion
A clear colorless solution thus obtained was heated for another 30 minutes to reduce the solution to almost one third of its original volume. The IR spectral measurements in 400-4000 cm-1 did not yield much information, as there was little difference in the different peak positions of the compounds from that of free triphenylphosphine. However, the low-frequency IR spectra (Figure 1) of the compounds yielded useful information about the compounds.
The intermediate intensity bands at 290 and 291 cm-1 for CuF(PPh3)3.2MeOH and CuF(PPh3)3.2EtOH, respectively, could be assigned Cu-F stretching frequency. Such a low molar conductivity in dichloromethane suggests the fact that the compounds remain practically undissociated in a relatively less polar solvent. On the other hand, much higher values in acetonitrile indicate significant dissociation of the products in a relatively more polar solvent.
Significantly, there was no plateau (even for a small temperature range) at the stage of 'CuF' formation except for a break with a change in gradient of the thermogram.
PART-B
For this purpose, the composition was subjected to the thermogravimetric experiment, because it was believed that such an experiment would provide data for the argument. It was then cooled to room temperature and left undisturbed for 2 hours, where pinkish-brown crystals of the compound formed. The main concerns were the development of a facile and direct synthesis of the compound and the investigation of its thermal behavior.
For example, the first step involved the preparation of the ammonium salt of MnF5, which was then reacted with NH4F and HF to give the compound. The compound has been shown to be stable for an extended period of time in the absence of moisture. The composition of the compound was ascertained by a number of physical techniques in addition to chemical estimation of manganese and fluoride.
The results of repeated determinations gave the magnetic moment value 4.7 BM indicating that the compound has a very low antiferromagnetic interaction.
An environmentally friendly biomimetic synthetic methodology for the bromination of organic
Details of the tools used for product characterization are listed in Chapter II.
The solvent was then removed in vacuo and the residue was purified by column chromatography (silica gel, hexane:ethyl acetate = 75:25) to give 1-bromo-β-naphthol. The solvent was then removed in vacuo and the residue was purified by column chromatography (silica gel, ethyl acetate) to give α,β-dibromocinnamic acid. The solvent was then removed in vacuo and the residue was purified by column chromatography (silica gel, hexane:ethyl acetate = 9:1) to give 9,10-dibromanthracene.
The solvent was then removed in vacuo and the residue was purified by column chromatography (silica gel, hexane) to give 2-bromocyclohexanone. The solvent was then removed in vacuo and the residue was purified by column chromatography (silica gel, hexane) to give 1,2-dibromocyclohexane. It is believed that under these conditions, H2O2 not only maintains the pH necessary for the formation of monoperoxovanadate(V) (as evidenced by the red coloring of the reaction solution and UV-Visible studies), but also partially regenerates the species after it is depleted . for the oxidation of bromide (Scheme 1). The H+ shown in Scheme 1 indicates the inherent acidity generated in the reaction solution).
Selected substrates with reaction times and product yields are presented in Table 1.
An acid assisted peroxo-molybdate(VI) catalysed methodology for in situ bromination of organic
With these in mind and also considering the general importance of broroaromatics, 6-13 we developed yet another methodology for bromination of organic substrates catalyzed by MoO42-. Details of the methodology, including its main benefits and environmental implications, are presented in this chapter. Details of tools used for product characterization are presented in Chapter II.
The pH of the reaction solution was observed to be about 1 at this stage, which rose to 2.1 at the completion of the reaction, indicating that the added acid had been partially consumed during the bromination process. Mechanistically, the reaction of the catalyst H2MoO4.H2O and H2O2 leads to the formation of oxodiperoxospecies MoO(O2)2 (λ = 328 nm) 14 below the pH of the reaction solution obtained after addition of a catalytic amount of HClO4. One of the major advantages of this method is that it yields regioselective products for most substrates.
The yields for the majority of the products reported herein have been high to very high (Table 1).
This chapter reports the details of the preparation and characterization of the reagent and the bromination of a few selected organic substrates with it. Two equivalents of potassium bromide was added to the reaction to increase the yield of the product. The identity of the compound was determined from the results obtained from various physical studies in addition to the chemical estimation of bromide.
The thermogravimetric analysis of the compound was also performed to determine if there was any correlation between thermal behavior and reagent efficiency. The solution electrical conductivity (10-3 M) of the compound at room temperature was measured to be 154 Ω-1 cm2mol-1. The electronic absorption spectrum (Fig. 3) of CTMATB in acetonitrile showed two absorption bands characteristic of Br3-.
The thermogram (Fig. 5) of CTMAB showed that there is a complete loss of the compound in a single step in the temperature range of C.
Introduction
Also presented are the results of FeCl3-catalyzed bromination of several aromatic compounds including chalcone by TBATB. Control experiment: Bromination of chalcone, aniline and phenol by tetrabutylammonium tribromide, (n-C4H9)4NBr3 (TBATB), in the absence of catalyst. The product yields were found to be much lower than those of the catalytic reactions although the reaction times were kept the same.
The electronic absorption spectrum of the compound in acetonitrile indicated that the intense color of the compound originates from charge transfer transition. After establishing the identity of the complex as [FeCl3Br]-, the same as that obtained in the bromination reaction involving Br2 and FeCl3 (catalyst), 1, 2 it was reasonable to say that the active brominating species in the bromination by Br2 also since Bu4NBr3 (TBATB) appears to be the same. For this purpose, bromination reactions of phenol, aniline and chalcone in acetonitrile by TBATB were carried out separately in the presence of the catalyst (also experimental) as well as in the absence of the catalyst (FeCl3).
Control reactions carried out for the same period of time in the absence of the catalyst gave
