Conservapedia - User contributions [en]

Chiral molecule

2009-11-11T21:45:18Z

GideonFox:

A '''chiral molecule''' is a molecule that cannot be superimposed on its mirror image. Chiral molecules are optically active in the sense that they rotate the plane of [[polarized light]].

An atom containing carbon forms optical isomers if one or more of the carbon atoms is bonded to four different species.

==Louis Pasteur==
[[Louis Pasteur]] encountered the phenomenon of optical activity in 1843, during his investigation of the crystalline sediment that accumulated in wine casks (a form of [[tataric acid]] called paratartaric acid - also called racemic acid, from the Latin racemus, "bunch of grapes"). He used fine forceps to separate two types of crystals identical in shape but mirror images of each other in structure. Both types proved to have all the chemical properties of tartaric acid, but in solution one type rotated plane-polarized light to the left (levorotatory), the other to the right (dextrorotatory). Pasteur later described the experiment and its interpretation:

<blockquote>
In isomeric bodies, the elements and the proportions in which they are combined are the same, only the arrangement of the atoms is differetn... We know, on the one hand, that the molecular arrangements of the two tartaric acids are asymmetric, and on the other hand, that these arrangements are absolutely identical, excepting that they exhibit asymmetry in opposite directions. Are atoms of the dextro acid grouped in the form of a right-handed spiral, or are they placed at the apex of an irregular tetrahedron, or are they disposed according to this or that asymmetric arrangement? We do not know.<ref>From pasteur's lecture to the Societe Chimique de Paris in 1883, quoted in DuBos, R. (1976) Louis Pasteur: Free Lance of Science, p. 95, Charles Scribner's Sons, New York.</ref>
</blockquote>

Now we do know. X-ray crystallographic studies in 1951 confirmed that the levorotatory and dextrorotatory forms of tartaric acid are mirror images of each other at the molecular level and established the absolute configuration of each. The same approach has been used to demonstrate that although the amino acid alanine has two stereoisomeric forms alanine in proteins exists exclusively in on form, the L-isomer (levorotatory).

==References==
<references/>

[[Category:Chemistry]]

Acyl halide

2009-11-11T21:29:05Z

GideonFox:

An '''acyl halide''', alternatively known as an '''acid halide''' is an organic compound consisting of the functional group RCOX, where R is a hydrocarbon chain and X is a halide, such as chlorine, bromine or iodine. They can be produced from a [[carboxylic acid]] by reacting it with a compound such as phosphorous trichloride (for chlorides) or phosphorous pentabromide (for bromides).

Acyl chlorides can be reacted with [[alcohol]] in order to produce an [[ester]] and an acid. This reaction provides a better yield than the alternative; reacting a carboxylic acid and an alcohol.

Acyl halide

2009-11-11T21:28:40Z

GideonFox: Created page with 'An '''acyl halide''', alternatively known as an '''acid halide''' is an organic compound consisting of the functional group RCOX, where R is a hydrocarbon chain and X is a halide...'

An '''acyl halide''', alternatively known as an '''acid halide''' is an organic compound consisting of the functional group RCOX, where R is a hydrocarbon chain and X is a halide, such as chlorine, bromine or iodine. They can be produced from a [[carboxylic]] acid by reacting it with a compound such as phosphorous trichloride (for chlorides) or phosphorous pentabromide (for bromides).

Acyl chlorides can be reacted with [[alcohol]] in order to produce an [[ester]] and an acid. This reaction provides a better yield than the alternative; reacting a carboxylic acid and an alcohol.

Aliphatic and aromatic compounds

2009-11-11T21:23:25Z

GideonFox:

In [[organic chemistry]], hydrocarbons can be divided into '''aromatic compounds''' which contain '''[[aromatic ring]]s''', also known as '''benzene rings''', and '''aliphatic compounds''' which do not.

Examples:
*Methane is an aliphatic compound, and contains no aromatic rings.
*Benzene is an aromatic compound, as it is an aromatic ring.
*Toluene is an aromatic compound, as it contains an aromatic ring bonded to a [[methyl]] group.

[[category:Organic Chemistry]]

Aliphatic and aromatic compounds

2009-11-11T21:23:09Z

GideonFox:

In [[organic chemistry]], hydrocarbons can be divided into '''aromatic compounds''' which contain '''[[aromatic ring]]s''', also known as '''benzene rings''', and '''aliphatic compounds''' which do not.

Examples:
- Methane is an aliphatic compound, and contains no aromatic rings.
- Benzene is an aromatic compound, as it is an aromatic ring.
- Toluene is an aromatic compound, as it contains an aromatic ring bonded to a [[methyl]] group.

[[category:Organic Chemistry]]

Alcohol

2009-11-11T21:21:28Z

GideonFox:

''This is an article about the chemical [[functional group]]. For the beverage, see [[alcoholic drink]]s''

'''Alcohols''' are a group of organic compounds consisting of a hydrocarbon or group with an -OH group; CnH2+1OH.

Commonly, the word alcohol refers to [[ethanol]] (C2H5OH), which is the alcohol found in [[alcoholic drink]]s. Ethanol is produced by yeast during the [[anaerobic]] [[metabolism]], comparable to the production of [[lactic acid]] in [[mammals]].

==Methanol==
[[Methanol]] consists of a single [[carbon]] atom, with three [[hydrogen]] atoms and a hydroxyl group (-OH). Traditionally, methanol was produced by the fermentation of wood, leading to the term 'wood alcohol'. Industrially, methanol can be produced by the reaction of [[carbon monoxide]] and [[hydrogen]] (CO + 2 H2 = CHO3OH). For this industrial process, copper, zinc oxide and aluminum oxide may be used as catalysts at 250°C and a pressure of 50-100 atm.

The primary use of methanol is its addition to ethanol to make it undrinkable. It has also been used as a [[biofuel]].

Methanol is highly toxic to humans. This toxicity is largely indirect, as alcohol dehydrogense metabolises methanol to form [[formaldehyde]], which causes blindness and death. Small amounts of methanol may be present in alcohol drinks are can cause a burning sensation of the eyes.

==Ethanol==
[[Ethanol]] (C2H5OH) is a major industrial spirit widely used in laboratories and household applications. It is also the type used in all [[alcoholic drink|alcoholic beverages]].

==Oxidation of Alcohols==
By heating a primary alcohol with an oxidising agent, such as acidified potassium dichromate, an [[aldehyde]] is formed. If the oxidation is down under reflux, the aldehyde will then itself oxidise to a carboxylic acid.

Secondary alcohols also oxidise, forming a [[ketone]]. Ketones, unlike aldehydes, cannot be oxidised further.

[[Category:Organic Chemistry]]

Carboxylic acid

2009-11-11T21:19:42Z

GideonFox:

'''Carboxylic acid''' is an [[organic molecule]] and an [[acid]] containing a carboxyl group, formula -COOH. They are a [[functional group]] present in both [[amino acids]] and [[fatty acid]]s.

Carboxylic acids are weak acids, and therefore dissociate incompletely in water, forming an equilibrium between the RCOOH molecule and the RCOO- and H+ ions.

==External Links==
[http://goldbook.iupac.org/C00852.html Carboxylic acids]

[[Category:Organic Chemistry]]

Aliphatic and aromatic compounds

2009-11-11T21:15:32Z

GideonFox: Created page with 'In organic chemistry, hydrocarbons can be divided into '''aromatic compounds''' which contain '''aromatic rings''', also known as '''benzene rings''', and '''aliphatic compou...'

In [[organic chemistry]], hydrocarbons can be divided into '''aromatic compounds''' which contain '''aromatic rings''', also known as '''benzene rings''', and '''aliphatic compounds''' which do not.

An aromatic ring is a cylic arangement of six carbon atoms, in which delocalised electrons in the unused p-orbitals overlap to form a ring shaped bond above and below the planar ring, making it more stable than would be expected. The simplest aromatic compound is [[benzene]], which consists of exactly one aromatic ring and is thus more stable than would otherwise be expected.

Examples:
- Methane is an aliphatic compound, and contains no aromatic rings.
- Benzene is an aromatic compound, as it is an aromatic ring.
- Toluene is an aromatic compound, as it contains an aromatic ring bonded to a [[methyl]] group.

[[category:Organic Chemistry]]