Beilstein test

Barbituric acid, 32, 7 Barium D-gulonate, 36, 39 Behenic acid, 37, 69 Beilstein test, 34, 38 Benzaldehyde, 30, 100 33, 70 34, 65 Benzaldehyde, p-AMINO, 31, 6 />-DIMETHYLAMINO-, 33, 27 Benzaldehyde, purification of, 33, 71 Benzalmalonic acid, ethyl ester, 37, S 4-Benzal-2-phenyl-5-oxazolone, 37, S Benzamidine, N,N -diphenyl-, 31, 48 N-phenyl-, 36, 64 Benzanilide, 31, 48... 

In the case of the benzyloxytrityl-hydroxylamineresin 24b, the starting material is the Merrifield resin, chloromethylated polystyrene (1.7 mmol Cl x g 1) which is treated with 3 equiv. of 4-hydroxy-methyl benzoate in DMA with sodium methylate as base. The Beilstein test is used for monitoring and microanalyses showed the absence of chloride (Scheme 6). 

With these solid supports in hand, we turned our attention to a new route to the synthesis of our target molecule 23 (Scheme 8). The tricky reductive amination should be replaced by an N-alkylation. To that end, bromoacetic acid is attached to 24c using DIC and Hiinig s base followed by the nucleophilic substitution with the corresponding benzy-lamine in DMSO/toluene (1 1), which can be easily monitored by the Beilstein test, followed by sulfonamide formation in DCM using N-methylmorpholine as base. For the final cleavage, 2% TFA in DCM is used and the resulting solution is filtered in a saturated NaHCC>3 solution to neutralise the acid before evaporation of the solvent. The crude product was then crystallised from ethyl acetate/heptane to yield the desired product in 27% yield overall and 99A% HPLC purity (see Table 4). 

The checkers yields were 74.8%-84.7% of analytically pure material giving a negative Beilstein test. 

Other investigators used flame emission as a modified Beilstein test for the detection of halogenated hydrocarbons. In such an arrangement, a green flame was produced when halogenated hydrocarbons were burned in the presence of a copper wire. Replacement of the copper with indium improves specificity and... 

The yield of dibromide dropped from 84% to 73% when no buffering sodium acetate was used. No improvement resulted from doubling the quantity of sodium acetate specified. Buffered bromination in a stirred suspension of acetic acid (no ether) at 20° raised the yield to 89%, but this material on debromination afforded sterol of low melting point (145-147°) containing halogen (Beilstein test). 

Purification of cholesterol through the dibromide completely eliminates cholestanol, 7-dehydrocholesterol, and latho-sterol (A7-cholestenol). The first crop of material from methanol-ether is also free from cerebrosterol (24-hydroxycholesterol) and 25-hydroxycholesterol, a product of autoxidation present in cholesterol that has been stored in the crystalline state for a few years with access to air. When material of highest purity is desired, only first-crop dibromide should be employed, since de-bromination of second-crop material gives sterol melting at 146-147° and giving a positive Beilstein test. 

Seyferth and coworkers99 described dehalocoupling of CH3HSiCl2 with Na (Wurtz coupling), to synthesize PMS (equation 34). CH3HSiCl2 is added slowly to a mixture of Na sand in 7 1 hexane THF with reflux under Ar for 20 h. The polymer product can be isolated in 60-70% yield as a viscous, hydrocarbon-soluble liquid that gives a negative Beilstein test for Cl. 

The stirrer is stopped, and the precipitate is allowed to settle. Unchanged alkyl halide is detected in the supernatant liquor by the Beilstein test (copper wire spiral) or by adding a few drops of the ethereal solution to alcoholic silver nitrate. 

Dissolve 0.5 g of triphenylmethanol in 10 mL of warm acetic acid, add 1.0 mL of 47% hydrobromic acid, and heat the mixture for 5 min on the steam bath or in a beaker of boiling water. Cool it in ice, collect the product on the Hirsch funnel, wash the product with water and ligroin, allow it to dry, determine the weight, and calculate the percent yield. Recrystallize the product from ligroin and compare the melting points of the recrystallized and crude material. The compound crystallizes slowly allow adequate time for crystals to form. Use the Beilstein test (Chapter 70) to test for halogen. 

The presence of halogens can be demonstrated by the Beilstein Test. A small amount of the sample is placed on a copper wire and burned in the Bunsen flame. The copper halide which forms imparts a green color to the flame. This test, though sensitive, must be conflrmed through fusion and detection by means of silver halide. 

D) Beilstein Test for Halogens. Heat a copper wire to redness until it no longer colors the flame. Cool, and touch it to a small crystal of p-dichlorobenzene then heat it again. A blue-green flame indicates the presence of a halogen. The color of the flame is due to the vapors of the copper halide. 

Beilstein test Blue/green flame in bunsen PVC, PVDC, neoprene, all... 

Sometimes it can be appropriate to carry out preliminary tests for readily detectable elements or compounds, for example the Beilstein test for organically bound... 

Determination of Haloalkanes A famous test used to determine if a compound is a haloalkane is the Beilstein test, in which the compound tested is burned in a loop of copper wire. The compound will bum green if it is a haloalkane. 

Qualitatively, these may be quickly detected by the Beilstein test for halogens a copper wire is heated in a gas burner until no color can be seen and the coil plunged into the acetic acid, then brought into the gas flame again. Any trace of green or blue-green flame shows the presence of halogen. The lower identification threshold is about 0.7 ppm for chloride, about 0.65 ppm for bromide, and about 0.55 for iodide. 

The flammability of plastics can be a useful tool in their identification, but the additives present have an influence on their ability to bum. A clear test to indicate the presence of chlorine, mainly found in PVC and poly(vinylidene chloride) is the Beilstein test. A clean, copper wire 30-40 cm long, with a cork or other heat-insulating material at one end as a handle, is heated with a Bunsen burner to clean it of residual impurities, heating it until the flame is colourless. The hot, cleaned wire is placed in contact with the plastic to be analysed so that a small piece is melted onto it. The wire is returned to the flame and the colour noted a green or blue-green flame denotes the presence of chlorine while other colours suggest the plastic to be other than PVC or poly(vinylidene chloride). 

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