Carbonyl compounds boiling points

The polarity of the carbonyl group is manifest in the physical properties of carbonyl compounds. Boiling points for the lower members of a series of aldehydes and ketones are 50-80° higher than for hydrocarbons of the same molecular weight this may be seen by comparing the data of Table 16-2 (physical... 

Sulfur Compounds. All crude oils contain sulfur in one of several forms including elemental sulfur, hydrogen sulfide, carbonyl sulfide (COS), and in aliphatic and aromatic compounds. The amount of sulfur-containing compounds increases progressively with an increase in the boiling point of the fraction. A majority of these compounds have one sulfur atom per molecule, but certain aromatic and polynuclear aromatic molecules found in low concentrations in crude oil contain two and even three sulfur atoms. Identification of the individual sulfur compounds in the heavy fractions poses a considerable challenge to the analytical chemist. 

Almost all the materials which are being considered as components in automobile exhaust catalyst are somewhat toxic (74)- Most of the compounds considered are low vapor pressure solids which can only escape from the exhaust system as very fine airbone dust particles formed by catalyst attrition. A few compounds, such as the highly toxic metal carbonyls and ruthenium tetroxides, are liquid under ambient conditions and have boiling points less than 100 °C. These compounds are not present in... 

The solvent process involves treating phthalonitrile with any one of a number of copper salts in the presence of a solvent at 120 to 220°C [10]. Copper(I)chloride is most important. The list of suitable solvents is headed by those with a boiling point above 180°C, such as trichlorobenzene, nitrobenzene, naphthalene, and kerosene. A metallic catalyst such as molybdenum oxide or ammonium molybdate may be added to enhance the yield, to shorten the reaction time, and to reduce the necessary temperature. Other suitable catalysts are carbonyl compounds of molybdenum, titanium, or iron. The process may be accelerated by adding ammonia, urea, or tertiary organic bases such as pyridine or quinoline. As a result of improved temperature maintenance and better reaction control, the solvent method affords yields of 95% and more, even on a commercial scale. There is a certain disadvantage to the fact that the solvent reaction requires considerably more time than dry methods. 

One of the most important uses of semicarbazide is as a reagent for identifying aldehydes and ketones [3]. Many semicarbazones have higher melting points and lower solubilities than the corresponding phenylhydrazones. The carbonyl compound is easily recovered by hydrolysis in boiling water. 

The hydrogen and halogen carbonyls and the nitroso carbonyls Co(NO)(CO)3, in which all bonds are covalent, are non-polar compounds with relatively low boiling points. The dimeric carbonyl, too, is non-polar, but its boiling point is much higher than that of the monomeric carbonyls because of the larger size of the molecule. 

The high boiling point of trifluoro(phenyl)-/l4-sulfane (4) enables reactions to be performed at atmospheric pressure in normal glassware. It is important that all reactions are carried out under anhydrous conditions and contact with glass be kept to a maximum of several hours to avoid hydrolysis (caution hydrolysis will liberate hydrogen fluoride). It has been reported that trifluoro(phenyl)-24-sulfane can convert carbonyl compounds to gem-difluorides, e.g. 5-6. 

Aldol condensations were originally carried out in the liquid phase and catalysed homogeneously by acids or bases this way of operation is still predominant. Solid-catalysed aldol reactions can also be performed in the liquid phase (in trickle or submerged beds of catalyst), but in many cases vapour phase systems are preferred the factors determining the choice are the boiling points and the stability of the reactants at elevated temperatures. At higher temperatures, the formation of a, j3-unsaturated aldehydes or ketones [reactions (B) and (C)] is preferred to aldol (ketol) formation [reaction (A)]. A side reaction, which may become important in some cases, is the self-condensation of the more reactive carbonyl compound if a mixed condensation of two different aldehydes or ketones is occurring. The Cannizzaro reaction of some aldehydes or polymerisation to polyols or other resin-like products can also accompany the main reaction. 

Because the hydrazone and semicarbazone derivatives of carbonyl compounds are often stable, crystalline solids, they used to be used to confirm the supposed identity of aldehydes and ketones. For example, the boiling points of... 

Hydrogen sulphide is a highly reactive substance and can react with most chemical compounds. With carbon dioxide it reacts to produce carbonyl sulphide, a highly toxic but also highly volatile compound (with a boiling point of -50°C) (Cantagrel etal. 1994). 

Balaban, A.T., Mills, D. and Basak, S.C. (1999). Correlation Between Structure and Normal Boiling Points of Acyclic Carbonyl Compounds. JChem.Inf.Comput.ScL, 39,758-764. 

In contrast to aliphatic alcohols, which are mostly less acidic than phenol, phenol forms salts with aqueous alkali hydroxide solutions. At room temperature, phenol can be liberated from the salts even with carbon dioxide. At temperatures near the boiling point of phenol, it can displace carboxylic acids, e.g. acetic acid, from their salts, and then phenolates are formed. The contribution of ortho- and -quinonoid resonance structures allows electrophilic substitution reactions such as chlorination, sulphonation, nitration, nitrosation and mercuration. The introduction of two or three nitro groups into the benzene ring can only be achieved indirectly because of the sensitivity of phenol towards oxidation. Nitrosation in the para position can be carried out even at ice bath temperature. Phenol readily reacts with carbonyl compounds in the presence of acid or basic catalysts. Formaldehyde reacts with phenol to yield hydroxybenzyl alcohols, and synthetic resins on further reaction. Reaction of acetone with phenol yields bisphenol A [2,2-bis(4-hydroxyphenyl)propane]. 

Toropov, A.A. and Toropova, A.P. (2002a) Modeling of acyclic carbonyl compounds normal boiling points by correlation weighting of nearest neighboring codes./. Mol. Struct. (Theochem), 581, 11-15. 

---