N-CO2 bond

Quaranta E, Aresta M (2010) The chemistry of N-CO2 bonds synthesis of carbamic acids and their derivatives, isocyanates, and ureas. In Aresta M (ed) Carbon dioxide as chemical feedstock. Wiley-VCH, Weinheim... 

The formation of the N-CO2 bond is relevant to industrial processes as it would allow the synthesis of carbamic acid derivatives avoiding the use of phosgene (Scheme 1.9). 

The insertion of CO2 into one N-Si bond occurs quite readily under standard conditions when R, R = Me formation of l,4-bis(0-trimethylsilylcarboxyl)-l,4dihydropyrazine, however, requires more drastic measures (60°C, 50 bar CO2) than previously suggested [3]. The latter compound exists as a mixture of cis and trans isomers due to restricted rotation around the N-C(=0) bonds on the NMR time scale [4],... 

The carbonylative ring-expansion reaction via CO insertion into the N-O bond has been applied to the six-membered ring system, that is, oxazines, but using Co2(CO)g as the catalyst. For example, the Co-catalyzed reaction of oxazine 242 at 120 °C and 68 atm of CO gave oxazepinone 243 in 53% yield (Equation (19)). ... 

The para-nitro ester 71d generated only 4-nitroaniline (70%) and 4,4 -dinitroazoxybenzene (10%) when it underwent decomposition (Scheme 29). These products could have been derived from either a triplet nitrene or a triplet nitrenium ion precursor. Homolysis of the N—O bond to generate radical intermediates was ruled out because of the nearly quantitative yield of pivalic acid derived from 71d. The pivaloxy radical would have undergone rapid decarboxylation to generate CO2 and the rert-butyl radical under these conditions. Since no rearrangement product was observed, it was tentatively concluded that this ester underwent direct decomposition to 4-nitrophenyl-nitrene without the intermediacy of a nitrenium ion. ... 

V02+ bonds most effectively to electronegative atoms, e.g. F, Cl, O and N, and bonds to S and P are also known.359 Fluoro and oxygen complexes are specially stable. Complexes with oxygen donors follow the expanded Irving-Williams series 354 VOz+ > Cu2+ > Ni2+ > Co2+ > Fe2+ > Mn2+. The presence of one or two nitrogen donors places V02+ lower in the series. 

In contrast to the isoxazolones, the isomeric 4//-oxazolin-5-ones which lack the weak N—O bond usually lose only CO upon pyrolysis. Thus, FVP of a variety of compounds 354 at 600°C gives the acylketenimines 355167. The 2//-oxazolin-5-ones do lose CO2 to give iminocarbenes, which may undergo rearrangement, as in the formation of 357 from... 

Notice that the nitronium ion (NO2) is linear with an sp hybridized nitrogen at the centre. It is isoelectronic with CO2. It is also very reactive and combines with benzene in the way we have just described. Benzene attacks the positively charged nitrogen atom but one of the N=0 bonds must be broken at the same time to avoid five-valent nitrogen. 

C104) crystallizes in 96% yield in a second-order asymmetric manner. The solution actually contains the equilibrium mixture A(jR) A(jR) = 7 3.1036 Both Co2, and OH- effect rapid mutarota-tion about the metal in this complex but not about the chiral carbon. With (S)-penicillamine a similar equilibrium obtains (A A[Co (S)pen (en)2]2+ = 7 3) but preferential crystallization does not occur.1037 X-Ray structures confirm equatorial and axial dangling carboxylate functions in A-[Co (R)cys (en)2](C104) and A-[Co (7 )cy s (en)2 ] (C104) H2 O respectively.1037 (N,S) bonding seems to be preferred in (N,S,0) systems (cysteine, penicillamine) but (N,0)[Co (R)cys (en)2]2+ has been prepared by reduction of the tridentate sulfenamide complex (285 equation 159).1038 This (N.O) chelate lacks the extended charge transfer absorptions in the near UV characteristic of thiolate coordination. 

A third kind of reactivity is related to the silyl substitution mechanism in that it involves an intermediate N-Si bond cleavage. Insertion of heterocumulenes such as CO2 is common for N-M bonds [7], including the -NSiR3 function in 1 or other molecules [8, 9]. We now report the result of the reaction between 1 and the unsymmetrical carbonyl sulfide, 0=C=S. 

No simple reactions between CO2 or CS2 and group IVB hydrides have been reported. On the other hand, a vast literature exists on insertion of CO2 and CS2 into N-H bonds. The reactions of NH3 with CO2 and CS2, to form ammonium carbamate and dithiocarbamate, respectively, are of commercial importance in the synthesis of urea, cyanates, and thiocyanates but are properly considered in the realm of organic chemistry. Secondary phosphines react with CS2 in the presence of a base ... 

In an individual molten carbamide, the electrode processes are feebly marked at melt decomposition potentials because of its low electrical conductivity. Both electrode processes are accompanied by gas evolution (NHs, CO, CO2, N2) and NH2CN (approximately) is formed in melt. In eutectic carbamide-chloride melts electrode processes take place mainly independently of each other. The chlorine must evolve at the anode during the electrolysis of carbamide - alkali metal and ammonium chloride melts, which were revealed in the electrolysis of the carbamide-KCl melt. But in the case of simultaneous oxidation of carbamide and NH4CI, however, a new compound containing N-Cl bond has been found in anode gases instead of chlorine. It is difficult to fully identify this compound by the experimental methods employed in the present work, but it can be definitely stated that... 

Aresta and coworkers have provided a very interesting example of C-N and N-H bond activation by use of low-valent nickel tricyclohexylphosphine complexes [86], Alkyl-ammonium or -imminium tetraphenylborate salts readily undergo oxidative addition to (Cy3P)2Ni(Tl -CO2) or (Cy3P)2Ni(p-N2)Ni(PCy3)j at or below room temperature, to yield the corresponding Ni(II) derivatives shown in Fig. 6.8. 

The pi bond in cii-dichloroethylene prevents rotation. 10.84 O3, CO, CO2, NO2, NjO, CH4, CFCI3. 10.86 C all single-bonded C atoms are sp, the double-bonded C atoms are sp N single-bonded N atoms are sp, N atoms that form one double bond are sp, N atom that forms two double bonds is sp. 10.88 Si has 3d orbitals so water can add to Si (valence shell expansion). 10.90 C sp N N atom that forms a double bond is sp, the others are sp. 10.92 (a) Use a conventional oven, (b) No. Polar molecules would absorb microwaves, (c) Water molecules absorb part of microwaves. 10.94 The small size of F results in a shorter bond and greater lone pair repulsion. 

The hydroxamic acid function in most alicyclic and aromatic compounds is stable to hot dilute acid or alkali, and derivatives cannot undergo normal base-catalyzed Lessen rearrangement. Di Maio and Tardella, however, have shown that some alicyclic hydroxamic acids when treated with polyphosphoric acid (PPA) at 175°-195° undergo loss of CO, CO2, or H2O, in a series of reactions which must involve early fission of the N—0 bond, presumably in a phosphoryl-ated intermediate. Thus, l-hydroxy-2- piperidone(108) gave carbon monoxide, l-pyrroline (119), and the lactams (120 and 121). The saturated lactam is believed to be derived from disproportionation of the unsaturated lactam. 

Whereas alkaline hydrolysis of (Z)-5-(ethoxycarbonylmethylene)-3-p-tolyl-5,6-dihydro-4//-l,2,4-oxadiazine (46 Ar = 4-MeC6H4) (see Section 6.14.9.2.2(i)) results in complete fragmentation of the molecule to yield 4-methylbenzamide, in hot dilute hydrochloric acid initial N—O bond fission is followed by ester hydrolysis and elimination of CO2 to give the amidoxime derivative (47) (Equation 2) <82CPB3987>. 

Toluene is a nucleophile, so HNO3 must be electrophilic. The N=0 bond in nitric acid is analogous to the C==0 bond in carbonic acid (HOCO2H). Just as HOCO2H decomposes to H2O and electrophilic CO2, so ONO2H decomposes to H2O and electrophilic N02-... 

The synthesis of the CO2-N2 compounds is a formidable challenge, largely because of the synthetic difficulties associated with N-O bonds. Nevertheless, syntheses of the monocyclic (C02)2N2 were suggested. 

Butadiene, which is bound in a n -manner to iron, reacts stoichio-metrically with carbon dioxide to form an allyl carboxylato complex in yields up to 75 % [38]. This allyl complex shows a dynamic behaviour Presumably three isomeric structures exist in solution, two of them with a n"-allyl bonding (Figure 16). Subsequent reactions of the allyl carboxylato complexes yield carboxylic acids. Acidic hydrolysis in methanol at -30°C gives methyl-3-pentenoate and methyl-4-pentenoate in a ratio of 10 1. If the iron allyl complex reacts with further carbon dioxide at 90 C, a second insertion of CO2 into the Fe-C-bond occurs after hydrolysis with hydrochloric acid in methanol the Z- and E-dimethyl esters of 3-hexenedioic acid are formed. 

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