Brominated aliphatic/aromatic

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

The N-bromination of amides with bromine and alkali has been extensively researched as the first step of the Hofmann degradation. However, it is difficult to isolate the N-bromoamides because of their subsequent reaction to produce amines, which proceeds very readily under excessive alkaline conditions. Now, the reaction of amides with a stoichiometric amount of BTMA Br3 and sodium hydroxide in ice-water gave N-bromoamides in fairly good yields. Our method can be applied to various types of aliphatic, aromatic, and heterocyclic amides (Fig. 31) (ref. 39). 

BFRs are one of the last classes of halogenated compounds that are still being produced worldwide and used in high quantities in many applications. In order to meet fire safety regulations, flame retardants (FRs) are applied to combustible materials such as polymers, plastics, wood, paper, and textiles. Approximately 25% of all FRs contain bromine as the active ingredient. More than 80 different aliphatic, cyclo-aliphatic, aromatic, and polymeric compounds are used as BFRs. BFRs, such as polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA), have been used in different consumer products in large quantities, and consequently they were detected in the environment, biota, and even in human samples [26, 27]. 

Various alkyl and aryl azides have been transformed into the corresponding nitriles using bromine trifluoride in moderate to good yields (30-60%).25 The reaction is general and gives positive results with aliphatic, aromatic, cyclic, functionalized, and optically active azides. Two alternative mechanisms have been proposed. 

As Table 10 illustrates, using this approach the authors were able to rapidly optimize the reaction conditions, obtaining the target 82 in 91% yield when employing 2 eq. of fenchone (80) and n-BuLi 74. In all cases only a single diastereomer was observed and the authors found that conducting the reaction at 0 °C resulted in a mere 3% reduction in yield. Furthermore, the reaction conditions were found to be suitable for a range of aliphatic/aromatic ketones and brominated compounds. 

Chemical Description Aliphatic Aromatic Bromine Low viscosity, excellent non-scorching flame retardant for flexible foam. 

Chemical Description Aromatic Bromine Aliphatic Chlorine Lower smoke and lower cost than brominated flame retardants, used to flame retard polypropylene, polyethylene, SBR, unsaturated polyesters and fabrics. 

Bromine, aliphatic and aromatic Bromine (aromatic) and chlorine Dover... 

Mixed Aliphatic-aromatic Ketone Arsinic Acids. —These compounds are formed by the interaction of bromine-substituted mixed aliphatic-aromatic ketones, such as 4-bromoacetophenone or. S-amino-4-bromo-acetophenone, with arsenites in hot solution. 

Under the preparation of brombenzene it has already been mentioned that by the action of chlorine or bromine on aromatic hydrocarbons containing aliphatic side-chains, different products are formed,... 

Halogenated flame-retardants may be either additive or reactive. The additive ones are aliphatic/aromatic or otherwise cyclic halogenated hydrocarbons. Generally their efficiency is inversely related to their thermal stability. The flame-retardant effect of the halogen atom (X) is increased by hydrogens on a vicinal carbon atom (as in aliphatic halogenated compounds) due to the ready scission of HX from the carbon chain. It is obvious, however, that these compounds are poor in thermal stability. The same is true for brominated flame-retardants they are more effective but less stable than chlorinated ones. For this reason, chlorinated paraffins and brominated aromatics are more commonly used as flame-retardants rather than aliphatic bromine compounds. 

Brominated dimethyisulphone dialkyl ether Bromine/chlorine containing flame-retardant Blend aromatic bromine, aliphatic chlorine... 

The classification of hydrocarbons as aliphatic or aromatic took place m the 1860s when It was already apparent that there was something special about benzene toluene and their derivatives Their molecular formulas (benzene is CgHg toluene is C7Hj ) indicate that like alkenes and alkynes they are unsaturated and should undergo addition reac tions Under conditions m which bromine for example reacts rapidly with alkenes and alkynes however benzene proved to be inert Benzene does react with Bi2 m the pres ence of iron(III) bromide as a catalyst but even then addition isn t observed Substitu tion occurs instead ... 

Suitable substrates for the Hunsdiecker reaction are first of all aliphatic carboxylates. Aromatic carboxylates do not react uniformly. Silver benzoates with electron-withdrawing substituents react to the corresponding bromobenzenes, while electron-donating substituents can give rise to formation of products where an aromatic hydrogen is replaced by bromine. For example the silver /)-methoxybenzoate 6 is converted to 3-bromo-4-methoxybenzoic acid 7 in good yield ... 

If a target aminodicarboxyl units bears an aryl group in one of its side chains, retrosynthetic analysis indicates that a bromoamide synthon 12, bearing an aliphatic side-chain, should react with a nucleophilic partner carrying the aromatic side chain. In the alternative bromoamide 21, HBr elimination to cinnamic derivatives competes with the desired bromine substitution. 

Aromatic and aliphatic bromine compounds play an important role as industrial products, e.g. special products are widely used as flame retardants for polymeric materials (ref. 1). Because there is an increasing interest and concern about the behaviour and fate of anthropogenic compounds in the environment (ref. 2), we have studied the physical behaviour and chemical reactivity of these products which are relevant to the environment. The main object is the study of their thermal behaviour during incineration, as well as photolytic reactions. Of prime concern is... 

Polypropylene. 3 series of experiments, in which the first stage was performed with Rr2 solutions of 3 different concentrations, at 28 C and various time intervals are summarized in Figure 1. The amounts of NH Br found in the polymer Increase with B concentration to a maximum concentration of 5.7% of NH Br. The 0.1. values of the samples (Fig. 1) appear to correlate closely with the NH Br. Table I shows the average effectivity, e.g. the slope of the plot of O.I. vs % Br for the PP fabric to be 1.24. This value is seen in Table II to be considerably higher than the value of 0.6 reported by van Krevelen [12] for aliphatic and aromatic bromine compounds and of 0.5 found bv Green [13] for aliphatic Br compounds. According to Green [13], 10% of aliphatic bromine are needed to produce a PP with an O.I. of 23.5, as compared to 4,6% Br from NH Br, which produced an 0.1. of 24.2 in the present experiments. 

In Figure 2, taken from reference [12], we inserted curve 5, which contains our present results. It is evident that the NH Br is more effective for PP than aliphatic or aromatic bromine throughout the 1-6% bromine range when no synergists are added. 

Decarboxylativehalogenation (12,417). The Hunsdiecker reaction is not useful for aromatic acids, but decarboxylative halogenation of these acids can be effected in useful yield by radical bromination or iodination of the thiohydroxamic esters, as reported earlier for aliphatic acids.1 Thus when the esters 2 are heated at 100° in the presence of AIBN, carbon dioxide is evolved and the resulting radical is trapped by BrCCl3 to provide bromoarenes (3). Decarboxylative iodination is effected with iodoform or methylene iodide as the iodine donor. 

No bromine ion is liberated when the analogous experiment is performed with bromobenzene (next preparation). Distinction between halogen in aliphatic and aromatic combination. 

PVDFs are not sensitive to most strong mineral and organic acids, oxidizing agents, aromatic and aliphatic hydrocarbons, some halogenated solvents, alcohols, bromine, metal salt solutions, or weak bases. 

There are many methods to brominate aromatic as well as aliphatic moieties [35]. Several involve the use of dibromodimethyUiydantoin (DBDMH) [36] and azoi-sobutyronitrile (AIBN) as a radical initiator, a combination which mainly bromi-nates aliphatic groups. DBDMH is synthesized by bromination of hydantoin with two moles of molecular bromine and yields two moles of hydrogen bromide as a waste by-product. 

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