Combination layers

A stirred solution of o-methylpivalanilide (50 mmol) in dry THE (100 ml) was maintained at 15°C under a nitrogen atmosphere. A 1.5 M solution of n-butyllithium in hexane (3 equiv.) was added dropwise. The solution was then maintained at room temperature for 16h. The solution was cooled in an ice-bath and treated with 2 N HCl (60 ml). The organic layer was separated and the aqueous layer was further extracted with benzene. The combined layers were dried (MgS04). The product was obtained in 87% yield and recrystallized from ether-cyclohexane. 

In a dry, 250 ml, three-necked flask equipped with a dropping funnel and magnetic stirrer are placed 40 ml of dry /-butyl alcohol (distilled from calcium hydride) and 4.0 g (0.036 mole) of potassium /-butoxide. The solution is cooled in ice and 40 g (49 ml, 0.49 mole) of dry cyclohexene is added. Bromoform (10 g, 3.5 ml, 0.039 mole) is added to the cooled, stirred reaction vessel dropwise over about hour, and the vessel is stirred an additional hour with the ice bath removed. The reaction mixture is poured into water (approx. 150 ml), and the layers are separated. The aqueous layer is extracted with 25 mi of pentane, and the extract is combined with the organic layer. The combined layers are dried (sodium sulfate), and the solvent is removed. The product is purified by distillation, bp 10078 mm. 

Pass the combined layers through a 2.5-cm thick layer of anhydrous sodium sulfate using Whatman no. 1 filter paper in a funnel, into a preweighed container suitable for a rotary evaporator. 

In recent years, interest in multiple-layered tablets as an oral controlled release system has increased. Multiple-layered tablets have some obvious advantages compared with conventional tablets. In addition to avoiding chemical incompatibibties of formulation components by physical separation, release profiles may be modified by combining layers with different release patterns or by combining slow release with immediate release layers. If the core layer of multilayered tablet is completely covered by a surrounding layer, the product is commonly referred to as a dry-coated tablet. An example is the Smartrix tablet, in which the release profile of a drug is determined by the increase in release surface caused by erosion (dissolution) of the cover layers.39... 

To a solution of 390 mg of 4-[3-methyl-trans-4a-cisoid-4a,5a-cis-5a-l,4a,5,5a,10b,10c-hexahydro-7-dioxino[5,4-a]cyclopenta[b]benzofuranyl] butyric acid in 5 ml of ethyl acetate cooled in an ice bath was added an excess of an ethereal solution of diazomethane, and after being stirred for 5 min the mixture was concentrated. The resulting oily material was dissolved in 3 ml of methanol, and to the solution was added 1 ml of 1 N hydrochloric acid and the mixture was stirred for 3 hours at room temperature. After concentration of the reaction mixture and addition of 1 ml of water, the mixture was extracted 3 times with each 5 ml of ethyl acetate. The combined layers of ethyl acetate were washed with 3 ml of water and 3 ml of aqueous saturated solution of sodium chloride, dried and concentrated to give 380 mg of crude crystals. The crude crystals were recrystallized from ethyl acetate-hexane to yield 200 mg of the pure captioned product (m.p. 56-57°C, yield 53%). 

DAST (0.60 ml, 4.6 mmol) was added to a solution of methyl 4,6-0-benzylidene-2-deoxy-3-oxo-a-D-erythro-hexopyranoside (0.315 g, 1.19 mmol) in dry dichloromethane (10 ml) under argon. The solution was stirred at room temperature for 2.5 h. The excess of DAST was neutralized by careful addition of saturated aqueous NaHC03. The combined layers were extracted (CH2CI2),... 

After the solution is cool, add about 15 mL of ethyl ether, pour the mixture carefully into about 15 mL of water (caution the reaction is exothermic), and mix well. Separate the aqueous layer, and extract it twice with 15-mL portions of ether. Wash the combined layer twice with 15-mL portions of saturated aqueous NaHCOs solution. Extract the washings twice with 15-mL portions of ether in each case, use the ether layer from the... 

Add a layer of liquid soap to the solution and watch it settle between the glycerin-water layer and the canola-oil layer. Now, when the combined layers are mixed (gently so as not to cause bubbles), the soap will cause the canola oil to blend with the glycerin. The result is a uniform... 

Adhesive characteristics of thin SPI-100 films could not be measured directly because adhesive forces are generally larger than cohesive forces. To obtain some information on adhesion values, thin high molecular weight SPI-100 films on substrates were overcoated with about. 1 mm of a commercially available polyimide (Product A) to provide greater cohesive strength than can be obtained with SPI-100 alone. The combined layers were then pulled in an Instron tester giving the results shown in Table II which also includes the values for commercial products A and B. 

Changes in the surface structure at different stages of the combined layer technology can be analyzed on very smooth mica substrates. The lines similar to those in Fig. 3a and composed of the grains were also seen in the SPM images of hybrid samples Ag/DNA/APTES/Si (Fig. 3b). The optical response of hybrid samples was studied taking into the presence of DNA and Ag nanoparticles on APTES-modified Si substrates. 

A mixture of 9.00 g (230 mmol) of KH (prewashed with pentane) and 290 mL of DME is treated, dropwisc and with stirring over 20 min, with a solution of 11.44 g (75 mmol) of the alcohol 2 in 30 mL of DME. After the resuliing mixture has been stirred at 25 C for 2 h (most of the KH has reacted) it is refluxed for 2.5 h at which time TLC and GC analysis of an aliquot indicates that the rearrangement is complete. After the reaction mixture has been cautiously siphoned into aq NH4C1, the combined layer and Ei.O extract of the aqueous phase are washed successively with aq NaHCO, and aq NaCI and then dried and concentrated. The residual crude liquid product (11.30 g) is fractionally distilled to separate 508 mg of fractions, bp 80 91 C (14 Ton), containing the ketone 3 and lower boiling impurities. Later distillation fractions contain (VPC) 8.90 g (78 %) of the ketone 3 (a mixture of stereoisomers) bp 91 93 C/14 Torr. 

A solution of methyl 4-chloro-3,3,4-trifluorocyclobut-l-enecarboxylatc (12 2.0 g, 10 mmol) in F.t20 (20 mL) was added dropwisc to a mixture of KOH (2.0 g) and ethanethiol (2.0 g). The mixture was stirred for 25 h. washed with H2C) (5()niL). and extracted with Et20 (4x20mL). The combined layers were dried and the solvent was evaporated to give a residue which was distilled in a Kugelrohr apparatus yield 2.67g (81 %) bp 130 C 0.05 Torr. 

D. Combination layers Some precoated TLC and HPTLC plates (Whatman Linear... 

The alkaline solution, thus obtained, is successively extracted with chloroform (200 ml). The combined layer of chloroform is evaporated under vacuo to obtain 15.5 g of a pasty mass. 

Rapid prototyping is an "additive process, combining layers of plastic to create a solid object. In contrast, most machining processes (milling, drilling, grinding) are "subtractive processes that remove material from a solid block. 

Other kinds of heat-based sterilization are used in food apphcations. For instancy retortable packaging is typically exposed to 120°C for 30 minutes or more in retort sterilization treatments that cook the food inside the package Used for hotels, restaurants, and the military, retortable pouches are made from multilayer films combining layers of POs and other polymers (see Case 16.1) [16-6]. 

A] thick film is a combination layer of volume phase... 

The upper layer can be adjusted with a choker bar, while the final combined layer thickness can be adjusted with the flex lip. 

Area 2 includes two sections of fabrics, each having the same lengths and possibly different weaves. However, the top fabric section is a combined layer made from top and middle fabric layers from area 1, and the bottom section is a single-layer fabric, the same as layer 111 in area 1. The weave for area 3 is the same as that for area 1, and area 4 is similar to area 2 except that the top section is a single layer and the bottom section is a stitched layer in this case. 

Data on reflectance of single-layer PS, double-layer PS, and combined layers used in silicon solar cell fabrication are given in Table 1. 

Economics. An advantage of coextrusion is the capability of combining layers of high performance resins with low cost resin layers to produce high per-formance/low cost composite structmes. The use of recycled and scrap resins in buried layers further improves economy. Multilayer extrusion economic considerations have been calculated (89). The effect of recycle on film properties, eg, tensile strength, impact, and elongation, depends on the degree of compatibiUty of polymers in the recycle layer. Often the tie-layer polymer acts as a compatibi-lizer for recycle. Recycle of incompatible polymers with different refractive indexes usually causes haziness and cannot be used when excellent optical properties are required. 

Structure design requires careful selection and planning because of the multitude of possible choices regarding material combinations, layer placement, layer thickness, etc. Often a coextruded film is further processed by lamination and coating into more complex structures to meet specific product application requirements. Theoretical design and product testing must be combined to yield the most efficient film structure for a specific application. Table 4 shows common designs that have evolved for the principal markets (100-102). 

---