Methyl-red, as indicator

I) The solution may be analysed approximately as follows. Remove 25 ml. of the ether solution and run it into 25 ml. of water contained in a small separatory funnel shake. Run off the aqueous layer into a 250 ml. conical flask and extract the ether layer with two 25 ml. portions of water. Titrate the combined aqueous extracts with 0 - IN sulphuric acid, using methyl red as indicator. 

The sodium carbonate content may be deterrnined on the same sample after a slight excess of silver nitrate has been added. An excess of barium chloride solution is added and, after the barium carbonate has setded, it is filtered, washed, and decomposed by boiling with an excess of standard hydrochloric acid. The excess of acid is then titrated with standard sodium hydroxide solution, using methyl red as indicator, and the sodium carbonate content is calculated. 

N-(Thexyl dimethylsilyl)dimethylamine (N-[2,3-dimethyl-2-butyl]dimethylsilyl dimethyl-amine) [81484-86-8] M 187.4, b 156-160°/720mm. Dissolve in hexane, filter, evaporate and distil. Colourless oil extremely sensitive to humidity. It is best to store small quatities in sealed ampoules after distillation. For estimation of purity crush an ampoule in excess O.IN HCl and titrate the excess acid with O.IM NaOH using methyl red as indicator. [Helv Chim Acta 67 2128 1984.]... 

Use as a color comparison a blank that has been ran on an equivalent amount of the distilled water used in foe determination, using Methyl Red as indicator... 

Thexyl dimethyl chlorosilane (dimethyl-[2,3-dimethyl-2-butyll chlorosilane) [67373-56-2] M 178.8, b 55-56°/10mm, 158-159 /720mm, d 0.970, n 1.428. Purified by fractional distillation and stored in small aliquots in sealed ampoules. It is very sensitive to moisture and is estimated by dissolving an aliquot in excess of O.IM NaOH and titrating with O.IM HCl using methyl red as indicator. [HCA 67 2128 1984]. 

Break the connections, wash the app with neutral distd w into the receiver and titrate the excess of acid with N/3 NaOH, using methyl-red as indicator... 

The yield of the Grignard reagent is estimated as follows A 50 ml. aliquotj is pipetted into a 250-ml. conical flask containing an excess (30 ml.) of 1 M hydrochloric acid. The ether is evaporated, and the excess acid is then back titrated with 1 M sodium hydroxide using methyl red as indicator. Typical yields are of the order of 60% of theoretical. 

Nitrogen is determined by the Kjeldahl method using Devarda s alloy. The complex and the alloy are placed in a standard Kjeldahl apparatus and the ammonia distilled off from a 7.5 M sodium hydroxide solution into 2% boric acid. The ammonia is titrated with standard hydrochloric acid using bromocresol green-methyl red as indicator. 

Determine the purity of your product by weighing out accurately two samples of about 2.5 millimoles and titrating with the standard decinormal base provided, using methyl red as indicator. 

This solution contains 24—30% benzyltrimethylammonium ethoxide (2.1-2.7 moles), as determined by titration with 0.1 N hydrochloric acid, using methyl red as indicator. This represents a yield of 67-90%. An additional 270 00 g. of solution is obtained by filtration of the residual mixture under nitrogen. To ensure rapid filtration, a filter aid, such as Filtered (Note 7), must be employed. The filtrate contains 24-30% benzyltrimethylammonium ethoxide (0.3-0.7 mole). The total yield is 89-100%. The solutions are stored under nitrogen and refrigeration in bottles sealed with rubber stoppers which are wired in place (Note 8). 

Af -Disalicylalethylenediamine. The salicylaldehyde is purified by the process of shaking or by standing in contact with powdered calcium carbonate, followed by distillation. To a solution of 244 g. (2 mols) of the purified material in 1 1. of boiling 95 per cent ethyl alcohol is added 60.1 g. (1 mol) of ethylenediamine this is measured by weighing out the appropriate amount of aqueous solution. If the concentration of the ethylenediamine is not known within a few per cent, a sample should be titrated against a standard acid, using methyl red as indicator. In 20 to 30 seconds the mass becomes sohd with formation of a bri t yellow, crystalline material. The reaction mixture is cooled and filtered on a Buchner fimnel, and the precipitate is spread in thin layers on absorbent paper to dry. It may be recrystallized from 61. of hot 95 per cent alcohol or used without further purification. It will dissolve somewhat more readily in the next step if it is not allowed to dry completely. Yield, 255 g. (95 per cent). The compound melts at 123°. 

The weighed sample of powdered tablet material is stirred with acetone, filtered using quantitative techniques, and titrated with perchloric acid in dioxane, using methyl red as indicator. The end point is from orange to salmon pink. 

To the percolate add 30 ml of N sulphuric acid, or sufficient to render the mixture faintly acid, shake well, allow to separate and run off the lower layer. Continue the extraction with 10-ml portions of 0-lN sulphuric acid until extraction of the alkaloids is complete, as shown by the iodine test. Wash the mixed acid solutions with about 10 ml of chloroform and run off the latter into a second separator containing 20 ml of 0 1 N sulphuric acid, shake, allow to separate and reject the chloroform. Repeat the washing of the liquid in the first separator with two further 5-ml quantities of chloroform, transfer each in turn to the second separator, wash with the same aqueous acid liquid, allow to separate and reject the chloroform layer as before. Transfer the acid liquid from the second separator to the first separator, make just alkaline with dilute ammonia solution and add 2 ml in excess shake with successive portions of chloroform until complete extraction of the alkaloids is effected, washing each chloroform extract with the same 20 ml of water contained in another separator. Remove the chloroform by distillation, add to the residue 2 ml of dehydrated ethanol, evaporate at a temperature not exceeding 60, and dry at a temperature below 60for thirty minutes. Dissolve the residue in 2 ml of neutral 95 per cent ethanol, warm until dissolved, add 20 ml of 0 02N sulphuric acid and 10 ml of water cool and titrate with 0-02N sodium hydroxide, using methyl red as indicator. 1 ml of 0-02N acid = 0-01291 g of the alkaloids of aconite calculated as aconitine. 

---