Polyhydroxy aldehyde

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars)... 

POLYHYDRIC ALCOHOLS AND THE POLYHYDROXY ALDEHYDES AND KETONES (SUGARS)... 

The simple sugars or monosaccharides are polyhydroxy aldehydes or ketones, and belong to Solubility Group II. They are termed tetroses, pentoses, hexoses. etc. according to the number of carbon atoms in the long chain constituting the molecule, and aldoses or ketoses if they are aldehydes or ketones. Most of the monosaccharides that occur in nature are pentoses and hexoses. 

Historically carbohydrates were once considered to be hydrates of carbon because their molecular formulas m many (but not all) cases correspond to C (H20) j It IS more realistic to define a carbohydrate as a polyhydroxy aldehyde or polyhydroxy ketone a point of view closer to structural reality and more suggestive of chemical reactivity... 

Over 200 different monosaccharides are known They can be grouped according to the number of carbon atoms they contain and whether they are polyhydroxy aide hydes or polyhydroxy ketones Monosaccharides that are polyhydroxy aldehydes are called aldoses, those that are polyhydroxy ketones are ketoses Aldoses and ketoses are further classified according to the number of carbon atoms m the mam chain Table 25 1 lists the terms applied to monosaccharides having four to eight carbon atoms... 

Carbohydrates are polyhydroxy aldehydes and ketones Those derived from aldehydes are classified as aldoses, those derived from ketones are ketoses... 

From the organochemical point of view, carbohydrates/polysaccharides are more or less substituted polyhydroxy aldehydes (e.g., glucose—>glucans) or polyhydroxy ketons (e.g., fructose-n fructans). From the physicochemical point of view, an enormous heterogeneity also exists in... 

Acetal and hemiacetal groups are particularly common in carbohydrate chemistry. Glucose, for instance, is a polyhydroxy aldehyde that undergoes an internal nucleophilic addition reaction and exists primarily as a cyclic hemiacetal. 

Carbohydrate (Section 25.1) A polyhydroxy aldehyde or ketone. Carbohydrates can be either simple sugars, such as glucose, or complex sugars, such as cellulose. 

Tannins comprise various polyhydroxyphenols and polysaccharides (polysaccharoses), which are complex carbohydrates (polyhydroxy aldehydes or ketones) and include starches and cellulose, and their... 

Parent monosaccharides are polyhydroxy aldehydes H-[CHOH] -CHO or polyhydroxy ketones H-[CHOH]n-CO-[CHOH]m-H with three or more carbon atoms. 

The reaction of aliphatic, aromatic, heterocyclic, conjugated, and polyhydroxy aldehydes with NBS and ammonia gave the corresponding nitriles in high yields at 0°C in water (Eq. 9.18).39 Ceric ammonium nitrate (CAN)40 and iodine41 are also effective as the oxidizing reagents. 

Carbohydrates are either polyhydroxy aldehydes and ketones or substances that form these compounds after hydrolysis. The general formula is [C (H20) ]. Normally carbohydrates occur as hemiacetals or acetals (hemiketals or ketals). 

Carbohydrates are the most abundant organic component of plants. Structurally, carbohydrates are usually polyhydroxy aldehydes or polyhydroxy ketones (or compounds that hydrolyze to yield polyhydroxy aldehydes and ketones). Since carbohydrates contain carbonyl groups and hydroxyl groups, they exist primarily as acetals or hemiacetals. 

Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis. Many, but not all, carbohydrates have the empirical formula (C1I20) some also contain nitrogen, phosphorus, or sulfur. 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

Fortunately, the rules of chemical reactivity and conformational analysis, coupled with the laws of thermodynamics, join forces to allow us to functionalize polyhydroxy aldehydes and ketones (aldoses and alduloses) in a selective and predictable fashion. 

Phenylhydrazinc, as hydrochloride solution plus sodium acetate, reacts with polyhydroxy aldehydes or ketones yielding osazones or diphenyl-hydrazones, yellow solids, of definite melting point and utilized in identification of sugars, e.g.. phenyl-d-glucosazone. CH OH (CHOH), C (NNHC6H5)CH (NNHCftH,) plus aniline C6H5NH plus NH,... 

The simple sugars, or monosaccharides, are the building blocks of carbohydrate chemistry. They are polyhydroxy aldehydes or ketones with five, six, seven, or eight carbon atoms that are classified appropriately as pentoses, hexoses, heptoses, or octoses, respectively. They can be designated by more... 

Carbohydrates are polyhydroxy aldehydes and ketones. Simple carbohydrates such as glucose can t be hydrolyzed to smaller molecules complex carbohydrates such as starch and... 

The basic carbohydrate molecules are simple sugars, or monosaccharides, which are polyhydroxy aldehyde, polyhydroxy ketone, and their derivatives. All simple monosaccharides have the general empirical formula, (CH20)n, where n is the whole number ranging 3 to 8. 

The simplest carbohydrates are the monosaccharides which under specified conditions are structurally characterised as polyhydroxy aldehydes or polyhydroxy ketones these are termed aldoses and ketoses respectively. Aldoses and ketoses are sub-classified, according to the number of carbons present in each molecule, into aldotetroses, aldopentoses, aldohexoses, etc., or ketotetroses, ketopentoses, etc. 

Notice that glucose is an aldehyde and fructose is a ketone. Polyhydroxy aldehydes like glucose are called aldoses. Polyhydroxyke-tanes like fructose are called ketoses. Carbohydrates are also named for the number of carbons they possess triose, tetrose, pentose, hexose, heptose, and so on. The names are commonly combined making glucose an aldohevose... 

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. 

Carbohydrate (Section 25.1) Naturally occurring compounds, often with the general formula C (H20) that are polyhydroxy aldehydes or ketones and derivatives formed from these includes sugars and starches. 

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