Urea-type compound

Demethylation at the nitrogen in position 6 could be realized by new modifications of the von Braun degradation. The 6-nor-6-cyano derivatives 46, obtained in the usual way by the action of cyanogen bromide on the parent compounds, could be reduced directly with zinc in acetic acid in good yield (46) to the 6-nor compounds (47). An alternative procedure was published independently by a Japanese group (47), using a two-step process via a urea-type compound 48. 

The catalyst (R = PhCH2, = H, R = OCO Bu), among more than 70 kinds of urea-type compounds examined, is found to be the most effective one with high catalytic turn over number. Good enantioselectivity is observed in a range of substrates [26] (Table 9.9). Although the size of the substituent in the catalyst is important, both yield and selectivity are unaffected by the geometry of imine substrates. 

More common than reductive methods on carbamate resins are substitution protocols which result in formation of urea-type compounds 207 that can be acyclic or even cyclic if the attacking amine is part of the solid-supported carbamate. 

Scheme 30 Synthesis of resin-bound carbamates and cleavage of urea-type compounds thereof...

The Israeli company Levgum have patented a process (US 6831109) based on a chemical method using a combination of two types of chemical compound a urea-type compound and a dicarboxylic acid-type compound. The former componnd dissociates to produce an organic cation and an amine, and the latter as a promoter of this... 

Linear guest molecules are included along these canals in an extended planar zig-zag conformation. Branched molecules are generally excluded unless branching occurs near the end of a long linear chain, but aromatic derivatives can be included if they have a long alkyl chain 38). The review article by Takemoto and Sonoda 21) contains an excellent survey of the types of molecules known to form urea inclusion compounds and of the means used to study their detailed conformations and thermal motion. 

Yet another type of canal structure has been reported for the urea inclusion compound of 1,4-dichlorobutane 51). Even though the canals are pseudo-hexagonal in dimension, there is a significant difference in their symmetry. The host lattice is orthorhombic, space group Pbcn. The difference lies in the directions of the six pseudo-3j helices of host molecules around the walls of each canal the sequence is cyc/o-RRRLLL, as opposed to cyc/o-RRRRRR in the hexagonal inclusion compounds and cvc/o-RLRLRL in the rhombohedral. This orthorhombic host structure probably occurs also in the urea inclusion compounds with 1,5-dichloropentane and 1,6-dibromohexane 51). 

Aliphatic hydrocarbons, triazine, substituted urea type and phenoxyacetic acid types of herbicides, Fluazifop and Fluazifop-butyl herbicides, ethylene diamine tetracetic acid salts in soil, aliphatic and polyaromatic hydrocarbons, phthalate esters, various organosulphur compounds, triazine herbicides, optical whiteners, mixtures of organic compounds and organotin compounds in non-saline sediments, aromatic hydrocarbons, humic and fulvic acids and mixtures of organic compounds in saline sediments and non-ionic surfactants and cobalamin in sludges. 

What kind of business This depends largely on what kind of dope you plan to manufacture. Amine-type precursors go hand in hand with perfumery or dyes. Nitrating-type compounds (nitromethane, nitroethane) are also used as solvents, and rocket fuels. Indole has been used in perfumery. Tyrosine and tryptophan are nutrients added to feeds. Urea is a plant fertilizer and a feed additive. 

A study of second-harmonic generation (SHG) from powders of l,3,5-triamino-2,4,6-trinitro benzene type compounds showed that the parent molecule 6 had an activity of about 3 x urea, whereas N-substituted derivatives were inactive (Ledoux, I. Zyss, J. Lehn, J.-M. Siegel, J. Brienne, M.-J., unpublished data). 

Applications of this technique are growing and include the analysis of mixtures of pesticides and herbicides, including oiganophosphorus, phenoxyacetic acid, caibamate, urea types, mixtures of various types of organic compounds, alkylbenzene sulphonates, polyethylene glycols, nonylphenyl ethoxylates, dioctadecylmethyl ammonium, ozonisation products and chlorination products. 

A laser flash study of the photoreactions of hexan-2-one and 5-methylhexan-2-one has provided evidence for the existence of the triplet 1,4-biradicals produced by the y-hydrogen abstraction typical of Norrish Type II reactivity. The photochemical behaviour of the alkanone, nonan-5-one, in urea inclusion compounds has been studied. In solution, irradiation of nonan-5-one yields hexan-2-one, propylene, and two cyclobutanols. In the clathrate, the fragmentation products were essentially the same but only one cyclobutanol was observed. The cyclization fragmentation ratio was established as 0.67, compared with 0.32 in methanol. The authors suggest that the CIS-cyclobutanol has less stringent rotational requirements and that it is this isomer (43) which is formed in the clathrate. 

Phosgenation of ethylene diamine type compounds is a well established method for the preparation of 2-imidazo-lidones (cyclic five membered ureas). The utility of this method is illustrated by the synthesis of a valuable intermediate (I) for D-biotine manufacture. We have developed an improved interfacial process which affords (I) in good yield and high purity as shown in scheme 213. 

Preservatives can be classified into two types compounds that release formaldehyde and compounds that do not release formaldehyde. Formalin, an aqueous solution of formaldehyde, is a commonly used preservative in shampoos and conditioners [3], Although formaldehyde has been known as a sensitizer, it is not a problem if used at 0.1 % or lower. The use of formaldehyde in baby shampoos is not recommended. Other preservatives that fall in the formaldehyde-releasing group are diazolidinyl urea, imidazolidinyl urea, and DMDM (dimethyloldimethyl) hydantoin. 

Applied to beans (Phaseolus vulgaris L.) epicotyls the compounds do not affect the normal growth of the plant. In this they are similar to herbicides of the carbamate and urea types. They do not affect the germination of the seeds, their main effect being manifested on the growing young plants. After normal growth of... 

A considerable amount of recent work has been directed towards the study of detailed molecular orientations and motions of guest molecules in urea channel inclusion compounds, as well as the generation of crystalline modifications in different space groups, such as P2i2i2i [30a,b] R3c [60] and Pbcn [67], but the principal structural characteristics of the channel-type host lattices remain virtually unaltered. Structural properties of the 1,10-dibromodecane/urea and 1,12-dibro-modecane/urea inclusion compounds have been determined by single-crystal X-ray... 

The channel-type host structure of 1.14 can be compared with those of the classical urea inclusion compounds, in which the separation between the centers of two adjacent channels is 8.2 A, leading to an effective cross-sectional diameter of... 

In one of the two urea-allophanate compounds (1.8, Figure 11), hydrogen-bonded zigzag ribbons are built up from repetition of the allophanate ion and one independent urea molecule joined together by a pair of N-H -O hydrogen bonds (LF type), whereas wide puckered urea and allophanate ribbons connected by hydrogen bonds exist in the other (1.9, Figure 38). 

Carbamates, urea, and triazine type compounds can be analyzed on an HPLC. For carbamates postcolumn derivatization technique may be applied. Carbamates separated on a C—18 column are hydrolyzed with NaOH and the products amines are then derivatized with cr-phthalaldehyde and 2-mercaptoethanol to... 

The high specificity obtained for optical resolution shows that it was in fact possible to copy the shape of the template and the arrangement of the functional groups into the polymer by this imprinting method. It should be noted that this method of resolution of racemates is a novel one. In this case no interactionsof the racemate with molecular parts carrying asymmetric carbon centers take place, but the enantiomers are bound within a chiral environment. The stability of these inclusion complexes is apparently different for the two enantiomers. This type of optical resolution is somewhat analogous to urea inclusion compounds ( ) or to silica imprinted by chiral compounds (27-29). Certain aspects of our method have been reviewed by our group (30-34) and by others (35-39). 

The host architecture has some gross structural characteristics, which are repeated in a series of its inclusion compounds. Among the most extensively studied channel-type inclusion coinpounds are the conventional urea inclusion compounds (see Urea), in which the urea molecules form an extensive hydrogen-bonded honeycomb network containing parallel helical tunnels (Fig. la) with diameter between 5.5-5.S A and the tunnel centers separated by ca. 8.2 The walls of the tunnels are... 

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