Vacuum steam distillation-extraction, method

Direct Injection of Amines. In the course of developing methods for investigation of in vivo formation of NMOR and NPYR in rats treated with precursor amines and nitrite, it was necessary to determine the contamination levels of the amines by the nitrosamines. Spiegelhalder et al (32) reported the presence of nitrosamines in all secondary and tertiary amine samples which they examined, using vacuum steam distillation followed by extraction and GC-TEA determination. 

The main distillation types include atmospheric, vacuum, steam, azeotropic, extractive, and pressure distillation [45]. AU of these distillation methods can be carried out in a batch or continuous marmer with the exception of extractive distillation, which is solely continuous by nature. Gomplex solvent systems often require the use of multiple distillation columns in series to purify certain solvents that are not easily separated. The energy consumption in distillation columns can therefore be quite large because of the continuous operation of condensers and reboilers over extended periods of time. In order to cut down on these costs, both vacuum and steam distillation can be employed ]45]. 

Our first separation method involved running the simultaneous steam distillation extraction under 100 mm vacuum in order to minimize heat effects. This was followed by extraction under atmospheric pressure in order to get more complete recovery. This atmospheric extraction was run for 10 days, using a fresh hatch of solvent each day (68-69). Approximately 10 times as much material was collected each day at atmospheric pressure as was collected under vacuum. Since Schultz, et. al. (70) showed that many non-water-soluble alcohols, esters, aldehydes, and ketones can he recovered by this system in less than 3 hours, the collection of a large amount of material after 10 days is indicative of a very complex and probably dynamic system. Gas chromatograms for these extracts (68.) and some compound identifications (69.) have been reported. (Other reports on the identification of volatiles from protein hydrolysates are given In references 71-75). Prelminary results have shown that the vacuum extracts are more attractive for the Medfly than the atmospheric ones. 

This method gives a somewhat tower yield than method 1. Dissolve 14.1 g l-nitro-3-butanone in 30 ml glacial acetic acid and heat to 35° add slowly with stirring to a solution of 5.3 g bromine in 10 ml glacial acetic acid. Evaporate in vacuum, dissolve residue in ether and wash with water, NaHC03 and water. Dry and evaporate in vacuum the ether (can distill 84/2) to get 6 g 1 -nitro-4-Br-3-butanone (1). Add 4.4 g (I) to 25 ml 48% HBr and reflux three hours. Add 50 ml water and steam distill. Neutralize the distillate with K carbonate and extract with ether. Dry and evaporate the extract (can distill 128/20) to get 5.6 g 2-Br-5-Br-methyl-isoxazole... 

As an alternative method of procedure, the following may be substituted for Steps 4 to 7 inclusive of the above process. After distilling the benzol, the tarry mass may be stirred directly with 2000 mL of hot 0.3 N NaOH with a mechanical stirrer. The suspension is chilled and the supernatant Liquid poured or siphoned off. Repetition of the extraction two or three times is advisable. The alkaline aqueous solution is then extracted five or six times with 400 mL portions of sulfuric ether, thus transferring the hormone to ether solution. After distillation of the ether the residue is steam distilled as long as a distillate other than water is obtained. The condensed water is removed by vacuum distillation and the small amount of dark tarry residue leached 5 times with 50 mL of hot 0.3 N NaOH. This solution is filtered and the filtrate extracted with sulfuric ether (100 mL, 6 times). The ether solution is distilled and the residue leached with cold 0.3 N NaOH using 20 mL five times. This alkaline solution is filtered and extracted with 50 mL of sulfuric ether five times. Upon distillation of the ether and solution of the residue in a small quantity of hot ethyl alcohol, the hormone separates in semi-crystalline balls which may be filtered off. A further quantity is obtained by adding 3 volumes of water to the alcoholic solution. It may be recrystallized from 25% aqueous ethyl alcohol or from 25% aqueous acetone or from any of the following chloroform, benzol, ethyl acetate, ethyl ether or petroleum ether. The final product consists of colorless crystals which, when crystallized from dilute alcohol, possess a distinct rhomboid outline. The crystals melt at 242-243°C (248-249°C corrected) with some decomposition. 

Distillation techniques, such as steam distillation, are typically carried out in a rotary evaporator after the sample has been solubilized in an organic solvent. The distillate is injected directly onto a suitable GC column. This method is used widely due to its simplicity and because components with high boiling points are recovered easily. High-vacuum distillation is used widely to isolate volatile components from solvent extracts. This procedure often requires an extraction step to remove water. 

B) Preparation of Quinoline (M.). The results are generally better by the macro method. Use five times the amount of reagents, and a 500-ml reaction flask. The condenser should be very efficient. Use same precautions given for the micro method in starting the reaction, and allow it to proceed without external application of heat for 15-20 minutes. Boil for four hours. Transfer the mixture to a two-liter Florence flask for steam distillation. Steam-distill until about 1500-1700 ml of distillate has been collected. Use three 60-ml portions of ether with a separatory funnel to extract the distillate, and for the remainder of the experiment proportionate amounts of reagents. After the final extraction and recovery of ether use a small flask for the final distillation. If a vacuum pump is available, use a small Claisen flask and distill under diminished pressure. Collect the fraction which boils at 116-122 at 20 mm pressure. 

Vacuum can be applied in order to reduce thermal exposure. The cooling funnel requires a deep-freezing mixture. This extraction method can easily be transferred onto an industrial scale. An important application is essential oils in water where steam distillation is carried out. For the distillative extraction process, different water-immiscible solvents are used. Thermal deterioration and retrieval ratio in the solvent have been studied intensively for fragrance materials [30],... 

The traditional method for alcohol purification is distillation. When the alcohol concentrations in the mixture and in the steam reach 95.57 and 97.6%, respectively, the mixture cannot be further purified, so a second distillation must be carried out. At present, the domestic secondary distillation methods include calcium oxide dehydration, azeotropic distillation, extraction distillation, absorption, molecular sieves, and vacuum dehydration. In addition, chemical film separation is a very promising alcohol purification technology, but it is still in the experimental stage. 

Traditionally-used techniques for the extraction of bioactive compounds are discontinuous, continuous, and hybrid approaches. The discontinuous techniques include the use of either organic solvents (sometimes assisted by ultrasound) or water, while steam distillation and vacuum distillation are continuous methods. Some methods involving both continuous and discontinuous approaches, such as distillation-extraction Soxhlet extraction has also been reported [14],... 

Steam distillation may be accomplished in several ways. The product may simply be put in a rotary evaporator (if liquid, or initially slurried in water if solid) and a distillate collected. This distillate would be solvent extracted to yield an aroma isolate suitable for GC analysis. The most common steam distillation method employs Simultaneous Distillation/Extraction (SDE may be called a Likens-Nickerson method). This is one of the oldest and most popular methods for obtaining aroma isolates. Chaintreau [31] has provided a very good review of this method and its evolution. An atmospheric pressure system is shown in Figure 3.4 (bottom). Vacuum systems must have joints that are air-tight, and all parts of the apparatus must be under rigid temperature control. 

Cocoa butter (also called cacao butter and theobroma oil) is produced commonly by three methods hydraulic pressing, extrusion or expeller pressing, and solvent extraction. Cocoa butter produced by the first two methods has a faint chocolate flavor and aroma that can be removed by steam distillation under vacuum it is brittle at temperatures below 25°C and melts at 34-35°C. ... 

Solvent Removal After extraction, chromatography, or completion of a reaction, it is frequently necessary to remove a solvent prior to further treatment of the product. An efficient method for accomplishing this is to use a solvent stripper as shown in Fig. 2-23. The sample to be concentrated is placed in a flask that is filled no more than half full, and a fine capillary tube (air or nitrogen bleed) is inserted through the distillation head to the bottom of the distilling flask. The solvent is heated with either a hot water or steam bath while aspirator vacuum is applied. If the rate of distillation... 

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