methylenedioxymethamphetamine (MDMA) See ecstasy.
methyl ethanoate (methyl acetate) A colourless volatile fragrant
liquid, CH 3 COOCH 3 ; r.d. 0.92; m.p.
–98°C; b.p. 54°C. A typical *ester, it
can be made from methanol and
methanoic acid and is used mainly as
a solvent.
methyl ethyl ketone See butanone.
methyl group (methyl radical) The
organic group CH 3 –.
methylidyne See carbyne.
methyl methacrylate An ester of
methacrylic acid (2-methylpropenoic
acid), CH 2 :C(CH 3 )COOCH 3 , used in
making *methacrylate resins.
methyl orange An organic dye
used as an acid–base *indicator. It
changes from red below pH 3.1 to
yellow above pH 4.4 (at 25°C) and is
used for titrations involving weak
bases.
methylphenols (cresols) Organic
compounds having a methyl group
and a hydroxyl group bound directly
to a benzene ring. There are three
isomeric methylphenols with the formula CH 3 C 6 H 4 OH, differing in the
relative positions of the methyl and
hydroxyl groups. A mixture of the
three can be obtained by distilling
coal tar and is used as a germicide
and antiseptic.
2-methylpropenoic acid
(methacrylic acid) A white crystalline
unsaturated carboxylic acid,
CH 2 :C(CH 3 )COOH, used in making
*methacrylate resins.
methyl red An organic dye similar
in structure and use to methyl orange. It changes from red below pH
4.4 to yellow above pH 6.0 (at 25°C).
methyl violet A violet dye used as
a chemical indicator and as a biological stain. It is also the colouring matter in methylated spirits. It is a
mixture of compounds of rosaniline,
made by oxidizing dimethylphenylamine with copper(II) chloride.
methylxanthines Derivatives of
xanthine in which one or more hydrogen atoms have been substituted
by methyl groups. The common ones
are the trimethylxanthine *caffeine
and the dimethylxanthines *theophylline and *theobromine.
metol See aminophenol.
metre Symbol m. The SI unit of
length, being the length of the path
travelled by light in vacuum during a
time interval of 1/(2.99 792 458 × 10
8
)
second. This deÜnition, adopted by
the General Conference on Weights
and Measures in October, 1983, replaced the 1967 deÜnition based on
the krypton lamp, i.e. 1 650 763.73
wavelengths in a vacuum of the radiation corresponding to the transition
353
metre
m
0
0
0
0
*
1
%
*
1
%*
0
0
0
0
1
%
*
1
%*
%*
0
*
0
0
0
1
1
%*
%*
VJGQRJ[NNKPG
ECHHGKPG
VJGQDTQOKPG
Methylxanthines
www.AzShimi.ir www.AzShimi.com
methyl ethanoate (methyl acetate) A colourless volatile fragrant
liquid, CH 3 COOCH 3 ; r.d. 0.92; m.p.
–98°C; b.p. 54°C. A typical *ester, it
can be made from methanol and
methanoic acid and is used mainly as
a solvent.
methyl ethyl ketone See butanone.
methyl group (methyl radical) The
organic group CH 3 –.
methylidyne See carbyne.
methyl methacrylate An ester of
methacrylic acid (2-methylpropenoic
acid), CH 2 :C(CH 3 )COOCH 3 , used in
making *methacrylate resins.
methyl orange An organic dye
used as an acid–base *indicator. It
changes from red below pH 3.1 to
yellow above pH 4.4 (at 25°C) and is
used for titrations involving weak
bases.
methylphenols (cresols) Organic
compounds having a methyl group
and a hydroxyl group bound directly
to a benzene ring. There are three
isomeric methylphenols with the formula CH 3 C 6 H 4 OH, differing in the
relative positions of the methyl and
hydroxyl groups. A mixture of the
three can be obtained by distilling
coal tar and is used as a germicide
and antiseptic.
2-methylpropenoic acid
(methacrylic acid) A white crystalline
unsaturated carboxylic acid,
CH 2 :C(CH 3 )COOH, used in making
*methacrylate resins.
methyl red An organic dye similar
in structure and use to methyl orange. It changes from red below pH
4.4 to yellow above pH 6.0 (at 25°C).
methyl violet A violet dye used as
a chemical indicator and as a biological stain. It is also the colouring matter in methylated spirits. It is a
mixture of compounds of rosaniline,
made by oxidizing dimethylphenylamine with copper(II) chloride.
methylxanthines Derivatives of
xanthine in which one or more hydrogen atoms have been substituted
by methyl groups. The common ones
are the trimethylxanthine *caffeine
and the dimethylxanthines *theophylline and *theobromine.
metol See aminophenol.
metre Symbol m. The SI unit of
length, being the length of the path
travelled by light in vacuum during a
time interval of 1/(2.99 792 458 × 10
8
)
second. This deÜnition, adopted by
the General Conference on Weights
and Measures in October, 1983, replaced the 1967 deÜnition based on
the krypton lamp, i.e. 1 650 763.73
wavelengths in a vacuum of the radiation corresponding to the transition
353
metre
m
0
0
0
0
*
1
%
*
1
%*
0
0
0
0
1
%
*
1
%*
%*
0
*
0
0
0
1
1
%*
%*
VJGQRJ[NNKPG
ECHHGKPG
VJGQDTQOKPG
Methylxanthines
www.AzShimi.ir www.AzShimi.com