Preparation benzene

Borazine, (HBNH)3, analogous to benzene prepared by A. Stock and E. Pohland. 

Prepare 6-methoxy-l-indanone (I) (JCS 1986(1962)) using polyphosphoric acid made by diluting 500 g of the commercial acid with 120 g 85% phosphoric acid. 2.5 g (I) in 176 ml ether and reflux one hour with 0.27 g lithium aluminum hydride. Cool and carefully add water and filter when bubbling stops (can use Celite filter aid). Dry and evaporate in vacuum and store twelve hours at -15° (under N2 if possible) to precipitate the white 6-methoxy-l-indanol (II) (recrystallize-n-hexane). 2.5 g (II) in 73 ml benzene and reflux one-half hour with 0.2 g p-toluenesulfonic acid. Cool, add water and separate the phases. Extract the aqueous phase with ether and combine with benzene phase and dry, evaporate in vacuum to get 5-methoxy-indene (III) (can distill 110-45/10). 1.53 g (III) and 1.39 g N.N-diethyl-aminoethyl-Cl.HCI in benzene (prepare the free base in benzene as described previously). Reflux four hours with 0.42 g sodamide, cool, wash with water and dry, evaporate in vacuum to get the indene analog of 6-methoxy DET as a dark liquid (can crystallize as oxalate). Alternatively, dissolve 2.51 g (III) in ether and treat (under N if possible) with 12 ml 1.6M buty-Li in hexane at 0-10°. After two hours cool to -30° and add 12 ml more of butyl-Li. Add ether suspension of 2.5 g N,N-diethylaminoethyl-CI. HCI over one-half hour and warm to room temperature. Filter, evaporate in vacuum to get the 6-methoxy-DET analog. 

Conveniently, ortho-substituted nitroso-benzenes prepared in a redox cell (vide supra) from the corresponding... 

Preparation of Antimony(III) Iodide. (Perform the experiment in the presence o/ your instructor in a iume cupboard, away from a flame ) Assemble an apparatus (see Fig. 119a). Place 1 g of finely triturated metallic antimony into a three-neck flask and add 25 ml of benzene. Prepare a solution of 4 g of iodine in 75 ml of benzene and pour it into dropping funnel 4. Heat the mixture in flask 1 in a water bath with stirring until it boils (use an electrical stove with an enclosed coil ). 

If either the o- or -position is occupied, only one isomer is obtained transformation to the mefo-position does not occur. This is a standard method of preparation of acyl-amino-ketones, or by a further hydrolysis of amino-ketones. The tendency, illustrated in this reaction, of groups to wander from the amino group to the nucleus, is also shown in previous reactions and in the preparation of aminoazobenzene from diazoamino-benzene (Preparation 456), of sulphanilic acid from aniline sulphate (Preparation 292), of o- and p-chloroacetanilides from acetochloranilide (Preparation 328), of o- and p-toluidine from methylaniline hydrochloride, and of 1 2 4-aminodimethylbenzene (2 4-xylidine) from dimethylaniline hydrochloride. 

Tanaka, K., Kakinoki, O., and Toda, F. (1992) Regio- and Enantioselective Photodimerisation of Cyclohex-2-enone as an Inclusion Complex with a New Optically Active Host, (-)-l,4-Bis[3-(o-chlorophenyl)-3-hydroxy-3-phenyl- l-propynyl]benzene Preparation of the Optically Pure (-)-symtram-Dimer of Cyclohex-2-enone, J. Chem. Soc., Perkin Trans. 1, 307. 

Fig. 5.8 Hexa(ferrocenyl)benzene, prepared in Peter Vollhardt s group by sixfold Negishi-type ferrocenylation of hexaiodobenzene and characterized by X-ray crystallography...

With (difluoroiodo)benzene, prepared from iodobenzene and xenon difluoride, as fluorinat-ing agent eYo-2-.vvH-7-difluoronorbornane becomes the main product. 

The ortho di-amino benzene prepared by the reduction of ortho-nitraniline is of special interest because of certain condensation reactions which it undergoes with aldehydes, ketones and nitrous acid. The meta compound also shows a characteristic reaction with nitrous acid. The para compound is readily oxidized and gives characteristic color reactions with ferric chloride and hydrogen sulphide. It is of importance in the preparation of dyes. All of these di-amines are colorless, crystalline solids which can be distilled. 

B) Preparation of Benzene. Prepare benzene by heating a mixture of 5 g of sodium benzoate with 4 g of soda lime in an ignition tube fitted with a cork and with a delivery tube leading into a test tube immersed in cold water. Note the characteristic odor of the distillate. Devise a test for proving the presence of benzene. Consult the instructor and perform the test. 

The benzene prepared in this way contains a small amount of diphenyl, which may be isolated from the residue left after the distillation of the hydrocarbon. The residue on crystallization from alcohol yields crystals of diphenyl, which after two sublimations melt at 71°. 

Figure 2.5.14 shows a synthetic route for pyriminobac-methyl [28]. The key step is ortho-lithiation reaction (step 3) of compound 21 protected by dimethylacetal and benzylation, followed by regioselective carbomethoxylation at the 2-position with methyl chloroformate via lithiated benzene prepared by n-butyllithium. Through several processes of deacetalization, methoxyimination of the acetyl group and debenzylation, compound 22 is condensed with DMSP 6 to give pyriminobac-methyl 15 [29]. 

The Nilsson synthesis of unsymmetrical biaryls derived from 1,3-dinitro benzenes Preparation of 4 -methoxy-2,6-dinitrobiphenyl (40) [37]... 

Recently, the Yankee Atomic Electric Company, Environmental Laboratory, has determined the tritium levels in water samples from the environs of several nuclear generating facilities in the New England area by liquid scintillation analysis of high purity tritiated benzene prepared from the water samples to be quantified. A commercially available unit was utilized to facilitate the synthesis of benzene by reacting the water sample with calcium carbide to form tritiated acetylene which is subsequently trimerized on a vanadium catalyst to high purity tritiated benzene. 

The potential reaction of the reducing agent 2 with hydrocarbon solvents like toluene and xylenes that contain benzylic hydrogens was investigated. When a solution of 2 in toluene (prepared in situ by sonication for 13 h) was quenched with methyl iodide or dimethyl sulfate, very small amounts (<6%) of ethyl benzene or xylenes were observed. When a solution of 2 in benzene (prepared in situ by sonication for 13 h) was quenched with methyl iodide or dimethyl sulfate, negligible amounts (<1.5%) of toluene were seen. Since the sonication conditions (42 C bath temperature, hot-spot peak temperature and pressure of about 3000K and 300atm, respectively, have been measured [81] ... 

Prepare individual standards (Sigma) of vitamin A palmitate, vitamin D2 (calciferol), and vitamin E (dl-a-tocopherol) as l-pg/pl solutions in benzene. Prepare each standard by dissolving 10 mg of the vitamin in 10 ml of benzene (benzene is a carcinogen and should be handled with extreme care). Prepare a mixed standard of the three vitamins by weighing 10 mg of each vitamin and dissolving in 10 ml of benzene to achieve a concentration of 1 pg/lil for each. 

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