Aldehydes, RCHO

The suffix -al is appended to the name of the hydrocarbon corresponding to the longest carbon chain that includes the aldehyde carbon. Remember that alkane- + -al becomes alkanal with the e omitted, and because the al function is necessarily at Cl, the -1- is redundant and is omitted  

Dialdehydes are named as -dials. Thus OHCCH2CH2CH2CH2CHO is hexanedial. 

The simplest aldehyde is methanal, HCHO, which is familiarly known as formaldehyde. However, when aldehydes are named as derivatives of methanal, they usually are called carbaldehydes, and the suffix carbalde-hyde refers to the —CHO group. This system is used where the hydrocarbon group is not a chain, but a ring, and the CHO group can be thought of as a one-carbon chain  

When the —CHO group is a substituent on the parent chain or ring and it ranks below another functional group, it properly is designated by the prefix methanoyl. However, the prefix formyl also is used  

Trivial names are used for many simple aldehydes, some of which are shown below in parentheses  

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Formaldehyde HCHO Acetylaldehyde CH3CHO Other aldehydes RCHO Acids... 

For the addition of an organometailic compound to an imine to give a primary amine, R in RCH=NR would have to be H, and such compounds are seldom stable. However, the conversion has been done, for R = aryl, by the use of the masked reagents (ArCH=N)2S02 [prepared from an aldehyde RCHO and sulfamide (NH2)2S02]. Addition of R"MgX or R"Li to these compounds gives ArCHR"NH2 after hydrolysis. ... 

The reaction to produce dioxanes has also been carried out with equimolar mixtures of formaldehyde and another aldehyde RCHO. The R appears in the dioxane on the carbon between the two oxygens Safarov, M.G. Nigmatullin, N.G. Ibatullin, U.G. Rafikov, S.R. Doklad. Chem., 1977, 236, 507. 

N-Trimethylsilylamides or lactams 344 react with sodium trimethylsilanolate 96 to generate the anhydrous N-sodium salts 345 and hexamethyldisiloxane 7 in practically quantitative yield [125]. Likewise, silylated succinimide 201 is converted by sodium trimethylsilanolate 96 into hexamethyldisiloxane 7 and the anhydrous sodium salt 346, which reacts with aldehydes RCHO (R=C2H5, n-C Hy), in the presence of catalytic amounts of 96 to give, via 346, the silylated adducts 347 in 43-62% yield [125]. The imide chloride 348 gives, analogously, sodium chloride and 7 and the N-sodium salt 349, which condenses in situ with unreacted imide chloride 348 to give 91% of the amidine 350 [126] (Scheme 4.46). 

Aliphatic or aromatic aldehydes RCHO can be transformed, in situ, via their iminium iodides, on reaction with enamines of ketones, to give /9-aminoketones. Thus, 4-methoxybenzaldehyde reacts with dimethylammonium chloride, triethyla-... 

On the basis of these experimental results, a possible mechanism has been proposed for the reaction of 1-215 with Sml2 (Scheme 1.52). After formation of the syn-complex A, a rearrangement occurs to give the aldehyde B, which coordinates to the added aldehyde RCHO to afford complex C. Subsequent samarium-catalyzed nucleophilic attack of the secondary alcohol to the carbonyl of RCHO generates a hemiacetal, D. There follows an irreversible intramolecular 1,5-hydride transfer via... 

Aldehydes RCHO NA Low molecular weight soluble, high molecular weight insoluble... 

C—Organic bases are, in general, amines (contain N). An ether would have an oxygen single-bonded to two carbons (R groups). An aldehyde has oxygen double-bonded to a carbon at the end of a chain. Aldehydes (RCHO) and... 

Protected primary allylic amines 210 are obtained208 as mixtures of (E)- and (Z)-isomers by the combined action of an aldehyde RCHO (R = CgHn, Ph, 4-MeOCgH4, i-CNCgPLt, PhCH=CH etc.) and triphenylphosphine on the aziridine 207 by way of an equilibrium mixture of the betaines 208 and 209. 

Tributylvinylphosphonium bromide forms the betaine 213 with sodium phthalimide. Addition of aldehydes RCHO (ketones are inert) gives almost exclusively the ( )-allylphthalimides 214, which form the corresponding allylamines by cleavage with hydrazine210. 

It has been shown22 that the reaction of the diene 4 with aldehydes RCHO in the presence of a catalyst prepared from (R)-BHMOL (33) and Ti(OPr-i)3, which affords the dihydro-y-pyrones 35 in good yields and high ee, proceeds by a two-step sequence via the open-chain adducts 34, which cyclize to the products on treatment with trifluoroacetic acid (equation 20). 

A convenient method for the conversion of aldehydes (RCHO) to alkenes (RCH = CHj), knovm as methylenation, involves the reaction of a zinc/copper couple with diiodomethane in the presence of the carbonyl compound dissolved in tetrahy-drofuran. The reaction first generates an organometallic intermediate (ICH2ZnI) which then reacts with the carbonyl compound. The conversion of benzaldehyde to styrene using this conventional methodology required a reaction time of 6 h at 40 °C. When the reaction was sonicated however comparable yields of around 70%... 

Alkanes n-butene, isopentane, isooctane Cydoalkanes t dohezane, methylcyclopentane Olefins (sometimes called alkenes ) ethylene, propylene, butene Cydoolefins ( clohezene Alkynes acetylene Aromatics toluene, i ene CHLORINATED HYDROCARBONS ALDEHYDES, RCHO formaldehyde, acetaldehyde KETONES, RCX R " acetone, methylethylketone NITRIC OXIDE, NO ... 

Aldehyde RCHO R Product Conversion (%) Yield (%) Diastereomer (I -R/r-S)... 

This treatment can be extended without mrxlification to polymers obtained from vinylidene monomers with different substituents (CH2=CR R2) and from aldehydes (RCHO) in which the oxygen atom replaces the methylene group. 

The two-electron oxidation of primary alcohols RCH OH to aldehydes RCHO is rarer with RuO than is the four-electron process to RCOOH (2.1, 2.4.1.1 Table 2.1). Examples include the reagents RuCyaq. Na(Br03)/( Bu N)Br/CH2Cl2... 

As complex/aq. H O /CH Cl they epoxidised unfunctionalised alkenes RCH=CHj to a mixture of the epoxide and the aldehyde RCHO with e.e. values from 4% to 41%. Thus (Z)-2-methylstyrene gave the cw-epoxide with only traces of the trans-isomer [928, 929]. The reagent [RuCl(PNNP)]Vaq. H O /CH Cl epoxidised cis-stilbene, Z-2-methylstyrene and 1,2-dihydro-napthalene [844]. 

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