Aldehydes carbons

A certain compound of molecular formula Ci9H3g was isolated from fish oil and from plank ton On hydrogenation it gave 2 6 10 14 tetramethylpentadecane Ozonolysis gave (CH3)2C=0 and a 16 carbon aldehyde What is the structure of the natural product" What is the structure of the aldehyde" ... 

Therefore one route involves the addition of a methyl Grignard reagent to a five carbon aldehyde... 

An a hydrogen of an aide hyde or a ketone is more acidic than most other protons bound to carbon Aldehydes and ketones are weak acids with pK s in the 16 to 20 range Their enhanced acidity IS due to the electron withdrawing effect of the carbon yl group and the resonance stabi lization of the enolate anion... 

Only one exception to the clean production of two monomer molecules from the pyrolysis of dimer has been noted. When a-hydroxydi-Zvxyljlene (9) is subjected to the Gorham process, no polymer is formed, and the 16-carbon aldehyde (10) is the principal product in its stead, isolated in greater than 90% yield. This transformation indicates that, at least in this case, the cleavage of dimer proceeds in stepwise fashion rather than by a concerted process in which both methylene—methylene bonds are broken at the same time. This is consistent with the predictions of Woodward and Hoffmann from orbital symmetry considerations for such [6 + 6] cycloreversion reactions in the ground state (5). 

The Other requires addition of a butylmagnesium halide to a two-carbon aldehyde ... 

Octyl Aldehyde.—The eight-carbon aldehyde has the formula CH3(CH2) CH0. 

Duodecylic Aldehyde.—The twelve-carbon aldehyde, also known as lauric aldehyde, has the conssitution CH3(CH2)j3CHO. It was originally introduced for blending with violet perfumes, but it is not very... 

Tetradecyl Aldehyde.— This is the highest of this series of aldehydes, and has the formula CH3(CH2)j2CHO. It resembles the thirteen-carbon aldehyde somewhat, and is very useful for blending in flower combinations. 

Wittig reactions are used commercially in tire synthesis of numerous pharmaceutical agents. For example, the German chemical company BASF prepares vitamin A by Wittig reaction between a 15-carbon ylide and a 5-carbon aldehyde. 

Attack of the OH radical on carbohydrates of low molecular mass gives rise to a variety of products. Indeed, the reaction of radiolytically-generated OH radical with lower hexose sugars produces lower saccharides (for di- and higher saccharide species), uronic and aldonic acids, and 3-, 2- and 1-carbon aldehydic fragments, e.g. 

Although the pyrolysis of some classes of polysaccharide materials has been studied quite extensively in the food, petrol and tobacco industry, very little has been published specifically on polysaccharide binders (arabic gum, tragacanth gum, fruit tree gum, honey and starch). The pyrolysis of glucane based polymers, especially cellulose, has been studied in detail [6,55], highlighting how anhydrosugars and furan derivatives are the main pyrolysis products, together with one-, two- and three-carbon aldehydes and acids. 

For an enantioselective synthesis of vinblastine (1) [or of leurosidine (56) and vincovaline (184, Scheme 49)], chirality at C-20 was introduced at the outset through Sharpless (131) oxidations of 2-ethylpropenol (185). Subsequent elaboration to the substituted five-carbon aldehydes 186... 

Small changes in the shape of the aldehydes have dramatic effects on reactivity with the encapsulated host-guest complex. For example, the host-guest complex reacts with isobutyraldehyde (entry 5) with a lower diastereoselectivity than with n-butyraldehyde (entry 3). This may be because the isobutyraldehyde complex is more spherical than the n-butyraldehyde complex. When comparing the five-carbon aldehydes (entries 6-8), only isovaleraldehyde undergoes C-H bond activation in 1. 

Essentially aldehydes exhibit the following properties (I) with exception of the gaseous formaldehyde, all aldehydes up to C31 aie neutral, mobile, volatile liquids. Aldehydes above Cn are solids under usual ambient conditions (2) formaldehyde and the liquid aldehydes have an unpleasant, pungent, irritating odor, (3) although the low-carbon aldehydes are soluble in H 0. the solubility decreases with formula weight, and (4> the high-carbon aldehydes are essentially insoluble in f 1,0. but are soluble in alcohol or ether. 

The word carbohydrate was used originally to describe glucose, which has the formula CgH Og and was once thought to be a "hydrate of carbon," Cft( H20)6. Although this view was soon abandoned, the word persisted and is now used to refer to a large class of polyhydroxylated aldehydes and ketones. Glucose, for example, is a six-carbon aldehyde with five hydroxyl groups. 

The alternative disconnection to CH3 and HCCH2CH2CH2CH3 reveals a plausible approach to 2-hexanol but is inconsistent with the requirement of the problem that limits starting materials to four carbons or fewer. The five-carbon aldehyde would have to be prepared first, making for a lengthy overall synthetic scheme. 

The disconnection shown leads to a three-carbon aldehyde and a five-carbon Grignard reagent. Starting with the corresponding alcohols, the following synthetic scheme seems reasonable. 

Figure 17. Free radical formation and browning in the reaction of two-carbon aldehydes with /3-alanine (each 1 M) in water. The mixtures were heated in a boiling water bath. Key for glycolaldehyde O, radical A, browning. Key for glyoxal , radical A, browning. (Reproduced with permission from Ref. 5.)...

Answer The carbon aldehyde-carbon bond must be cleaved. Looking at procedure XlV-Sa, it can be readily seen that the formyl group in XlV-e comes from ethyl formate E while the other carbon cleaved must come from tile starting ester A. This carbon must have had a hydrogen removed in the formation of the product XIV-c. Thus we must reattach a hydrogen to identify the structure of the starting ester. 

Many carbohydrates fit the general formula Cv(H20)T, so it is apparent how the name originated. Actually, they are polyhydroxy aldehydes or ketones. Glucose, C6H 206, is a typical monosaccharide. It is a six-carbon aldehyde with hydroxy groups on all of the other carbons. 

We need to add two groups to acetylene an ethyl group and a six-carbon aldehyde (to form the secondary alcohol). If we formed the alcohol group first, the weakly acidic —OH group would interfere with the alkylation by the ethyl group. Therefore, we should add the less reactive ethyl group first, and add the alcohol group later in the synthesis. 

As discussed earlier, the sixteen carbon aldehydes, used as pheromone components by all Heliothis species studied to date, are formed by the action of a primary alcohol oxidase in H. virescens. 

In summary, the pheromone blends produced by Heliothis species are generated by a common biosynthetic scheme which permits modifications that result in the production of species specific blends of pheromone components. Pheromone mediated reproductive isolation between H. zea and the other two species results from the fact that H. zea does not produce fourteen carbon aldehydes. 

Having determined that the high polarity cyano phase and the liquid crystal phase provide the best separation of the compounds likely to be found as components of the pheromone blend of H. virescens and H. subflexa, we analyzed a complex mixture of positional and geometrical isomers of 16 carbon aldehydes, alcohols, and acetates on these two columns (Figure 7). As noted earlier, the elution order of Z- and JE-isomers is opposite on the two phases. Aldehydes elute first on both phases. The alcohols are retained more than the acetates on the high polarity cyano phase, but the elution order of alcohols and acetates is reversed on the liquid crystal phase. While neither phase separated all of the synthetic mixture, the combination of separations obtained on both columns enabled us to pursue the... 

Capillary GC analyses on SP-2340 and OV-101 columns of the extracts of the DV and the ISM indicated distinct differences in the contents of these two glandular sites. The DV contained predominantly the 14-carbon aldehydes while the ISM contained primarily the 16-carbon compounds. Contamination of either site by small quantities of material from the other is likely because of the difficulty in excising the individual glands. However, there were distinct differences in contents of pheromone components in the two sites. Although the significance of this finding is not clear at this time, it should be noted that the 14-carbon aldehydes have not been found in other Heliothis species and Z9-14 Al is a major factor in separating H. virescens and H. zea (121. 

Evaluation of this system with standards (Table ll indicated that most 14- and 16-carbon aldehydes, acetates, and alcohols could be recovered with good efficiency. Recoveries vary with conditions, and thus it is necessary to calibrate an apparatus with standards under the exact conditions to be used with insects. For example, larger diameter aeration chambers reduce the efficiency of collection because of the greater surface area of glass available to adsorb the pheromone and lower wind velocities for a given flow rate. Therefore, the smallest aeration... 

The differences in the glandular pheromone constituents between H. virescens and H. subflexa are distinct. H. subflexa contains acetates of 16-carbon alcohols not found in H. virescens and does not contain the 14-carbon aldehydes which appear to be unique to H. virescens among Heliothis species studied thus far. It will be interesting to see what blends the hybrids of these species produce and relate this to data from investigations of the genetics of this hybridization. 

A selection of A//p gp values has already been given in Table 2-4 in Section 2.2.6. This new Lewis basicity scale is more comprehensive and seems to be more reliable than the donor number scale. Analogously, a Lewis basicity scale for 88 carbonyl compounds (esters, carbonates, aldehydes, ketones, amides, ureas, carbamates) has been derived from their standard molar enthalpies of complexation with gaseous boron trifluoride in dichloromethane solution [143]. The corresponding Aff Q gp values range from 33 kJ mol for di-t-butyl ketone to 135 kJ mol for 3-diethylamino-5,5-dimethyl-cyclohexen-2-one. 

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