Condensation products with the

Another aspect is that the two reactants should yield a condensation product with the elimination of a small molecule, e.g., H2O. This is not essential. Thus in... 

Figure 4. Possible conformations of coordinated S-ampr (8 and ) and the structure of condensation products with the single linkage (a and b)...

It clearly differentiates between aldehydes and ketones by forming insoluble condensation products with the former, but not with the latter. 

Carotenoid aldehydes form intensely coloured condensation products with the rhodanine reagent (No. 222) after drying, which serve for identification. As little as 0.02—0.03 g retinal can be seen as an orange-red spot [150]. Blue to deep violet complexes, depending on the compound, are yielded with the indandione reagent (No. 138). The sensitivity is similar and they also fluoresce orange in UV light [133] (Fig. b, Plate II). 

CH-acidic component (R ==CO Et), none of the desired products could be isolated, even within extended reaction times of up to 240 min instead, only the Knoevenagel condensation product with the aldehyde and the shown by-product 326 were formed. The latter one arises from a dimerization of compound 323 in a homo-Diels-Alder reaction. 

The DKR procedure described above was improved by Meijer and coworkers in 2007 [87]. The protocol was improved both in terms of reaction time (26 h instead of 72 h) and the required amount of acyl donor (the excess acyl donor could be reduced to 1.1 equiv). This was accomplished using a more effective acyl donor isopropyl 2-methoxyacetate for the enzymatic acylation. CALB was used for the kinetic resolution, and the para-methoxyphenyl derivative of the Shvo catalyst was used for racemization (22). All the DKR reactions were performed under reduced pressure (750 mbar) to eliminate the isopropyl alcohol from the reaction mixture. The isopropyl alcohol can be oxidized to acetone, and the latter can in subsequent reaction steps form unwanted condensation products with the amine substrates. The revised protocol afforded the products with excellent selectivity (96-99% ee). The yields were slightly lower (56-80%) than those obtained with the Backvall protocol [86], mainly due to problems with purification. 

After about 20 minutes, when the liquid should be dry, filter it through a small fluted filter-paper into a 100 ml. distilling-flask attached to a water-condenser. Add some fragments of unglazed porcelain to the ethyl acetate, fit a 100° thermometer to the flask, and place the latter on a cold water-bath, which is then brought to the boil. Some ether is always formed as a by-product with the ethyl acetate, and by these means is carefully distilled off as a... 

Note that p-acetamidobenzenesulphonyl chloride will similarly react with primary and secondary amines, and the products, after hydrolysis of the acetyl group, may furnish notable drugs e.g., the condensation products with 2-amino-pyridine and 2-aminothiazole, after remo al of the acetyl groups, provide the drugs commonly known as sulphapyridine (M B 693) and sulphathidzole respectively. 

Many of these are crystalline compounds of sharp m.p. and are therefore useful for identification and characterisation. These include the condensation products with ... 

Amino-5-nitrothiazole, on treatment with arenesulfonyl halides and dimethylformamide at 140 C, gives (5-nitro-2-thiazolyl)amidme (274) (Scheme 168) (507, 508). The condensation products of the reaction of 2-aminothiazole derivatives with various aldehydes are grouped in Tables... 

Foam spray dryiag coasists of forcing gas, usuaHy air or nitrogea, iato the product stream at 1.38 MPa (200 psi) ahead of the pump ia the normal spray dryer circuit. This method improves some of the characteristics of dried milk, such as dispersibHity, bulk deasity, and uniformity. The foam—spray dryer can accept a condensed product with 60% total soHds, as compared to 50% without the foam process. The usual neutralization of acid whey is avoided with the foam—spray dryer (see Drying Foams Sprays). 

Sasol Fischer-Tropsch Process. 1-Propanol is one of the products from Sasol s Fischer-Tropsch process (7). Coal (qv) is gasified ia Lurgi reactors to produce synthesis gas (H2/CO). After separation from gas Hquids and purification, the synthesis gas is fed iato the Sasol Synthol plant where it is entrained with a powdered iron-based catalyst within the fluid-bed reactors. The exothermic Fischer-Tropsch reaction produces a mixture of hydrocarbons (qv) and oxygenates. The condensation products from the process consist of hydrocarbon Hquids and an aqueous stream that contains a mixture of ketones (qv) and alcohols. The ketones and alcohols are recovered and most of the alcohols are used for the blending of high octane gasoline. Some of the alcohol streams are further purified by distillation to yield pure 1-propanol and ethanol ia a multiunit plant, which has a total capacity of 25,000-30,000 t/yr (see Coal conversion processes, gasification). 

Upon mashing, small amounts of tannin go into the solution from the malt, and later, during the boiling with hops, more tannin goes into the wort. Tannins from both barley and hops are leucoanthocyanin stmctures, in some cases they are derivatives of quercetin [117-39-5], cathechins are not found. The turbidities in beer, rich in leucoanthocyanins, are composed of peptones, peptides, and condensation products of the tannins of malts and hops. 

Madsen and Lavvesson (6/), however, have reported recently that the treatment of /7-alkyl methyl ketones with morpholine in the presence of p-toluenesulfonic acid for a short period of time resulted in the formation of a mixture of condensation product of the ketone (122) and the corresponding dienamine (123). 

Comforth has reviewed literature reports and independently studied the special cases of reaction of 1 with salicylaldehyde and with 2-acetoxybenzaldehyde. Coumarins (10) are afforded in the condensation of 1 with salicylaldehyde or its imine, whereas when 2-acetoxybenzaldehyde is used, acetoxy oxazolone 12 is the major product. The initial aldol condensation product between the oxazolone and 2-acetoxybenzaldehyde is the 4-(a-hydroxybenzyl)oxazolone 11, in which base-catalyzed intramolecular transacetylation is envisioned. The product 9 (R = Ac) can either be acetylated on the phenolic hydroxy group, before or after loss of acetic acid, to yield the oxazolone 12, or it can rearrange, by a second intramolecular process catalyzed by base and acid, to the hydrocoumarin, which loses acetic acid to yield 10. When salicylaldehyde is the starting material, aldol intermediate 9 (R = H) can rearrange directly to a hydrocoumarin. Comforth also accessed pure 4-(2 -hydroxyphenylmethylene)-2-phenyloxazol-5(4//)-one (13) through hydrolysis of 12 with 88% sulfuric acid. 

Oximes.—Most aldehydes yield a condensation product with hydroxyl-amine, according to the equation —... 

Phenylhydrazones.—Nearly all aldehydes form condensation products with phenylhydrazine, known as phenylhydrazones, according to the following equation —... 

Doebner showed that certain aldehydes, citral, for example, form condensation products with pyruvic acid and )8-naphthylamine, known as naphthocinchoninic acids. The reaction takes place as follows —... 

The process for the production of the ionone referred to in the second claim, consisting in treating the pseudo-ionone referred to in the first claim or its ketone condensation products with phenylhydrazine or other ammonia derivatives, finally with acids, substantially as described. 

The starting material is prepared by reacting 1-benzyl-4-piperidone with aniline, reducing the condensation product with lithium aluminum hydride, reacting the product thus obtained with propionic anhydride, than hydrogen. 

The exact position of the aldol equilibrium depends both on reaction conditions and on substrate structure. The equilibrium generally favors condensation product in the case of aldehydes with no a substituent (RCH2CHO) but favors reactant for disubstituted aldehydes (R2CHCHO) and for most ketones. Steric Factors are probably responsible for these trends, since increased substitution near the reaction site increases steric congestion in the aldol product. 

The strategy for the construction of 13 from aldehyde 16 with two units of phosphonate 15 is summarized in Scheme 12. As expected, aldehyde 16 condenses smoothly with the anion derived from 15 to give, as the major product, the corresponding E,E,E-tri-ene ester. Reduction of the latter substance to the corresponding primary alcohol with Dibal-H, followed by oxidation with MnC>2, then furnishes aldehyde 60 in 86 % overall yield. Reiteration of this tactic and a simple deprotection step completes the synthesis of the desired intermediate 13 in good overall yield and with excellent stereoselectivity. 

Dimedone reacts with carbonyl compounds with the elimination of water yielding the condensation product [1]. The reaction is specific for ketoses aldoses do not react or only weakly [6],... 

---