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- Both aldehydes and ketones contain carbonyl group C=O. - The difference between aldehyde and ketone was found to be:. Aldehydes and Ketones. In aldehyde C=O attach with H and R i.e. In ketone C=O attach with two R. General formulae of aldehyde and ketones.
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- Both aldehydes and ketones contain carbonyl group C=O. - The difference between aldehyde and ketone was found to be: Aldehydes and Ketones • In aldehyde C=O attach with H and R i.e • In ketone C=O attach with two R
General formulae of aldehyde and ketones Nomenclature of Aldehydes and Ketones • I) IUPAC: • A) Aldehyde • 1- يتم ذكر أسم alkane باستبدال حرف e في alkane بمقطع al e.g. Methane Methanal Ethane Ethanal
2 - لأن مجموعة CHO توجد غالبا في طرف السلسلة فلا يذكر رقمها • 3- في حالة وجود فروع يتم ترقيم السلسلة بإعطاء مجموعة الألدهيد بالرقم 1 • Examples: 4- ي حالة احتواء السلسلة علي يتم ذكر أسم alkeneباستبدال حرف e في alkene بمقطع al
5- فى حالة احتواء السلسلة علي يتم ذكر أسم alkyne باستبدال حرف eفي alkyne بمقطع al Examples:
2) Common name • تتم بذكر اسم الحمض محذوفا منه مقطع oic و استبداله ب aldehyde • Examples ;
B) Iupac nomenclature of ketones • يتم ذكر أسم alkane باستبدال حرف e في alkane بمقطع one Example: Propane Propanone 2 - يتم ترقيم السلسة من الطرف الذي يعطي ل C=O أقل ترقيم Common system of ketones: -نذكر أسماء alkyl حول C=O ثم نكتب كلمة ketone في النهاية.
Preparation of aldehydes & ketones: • From acid chloride: • This method is called Rosemund reduction. • ملحوظة: فائدة Pd-BaSO4 catalyst انه يوقف الاختزال عند مرحلة ald. ولا يختزل ald. إلى كحول.
(2) From geminal dihalide:أي ذرتي هالوجين على نفس ذرة الكربون Question: convert toluene to benzaldehyde Answer
(3) Partial decarboxylation of salt of acids: Question: Show how could you prepare the following by above method, we use two molecules • To prepare
Question: Show how could you prepare the following • الطريقة السابقة تستخدم لتحويل الأحماض إلي الدهيدأو كيتون كالأتي Example conversion of
(4) From nitrile: a- Aldehyde: b- Ketone Methods have been studied :
(5) Oxidation of alcohols: a- Aldehyde: From oxidation of primary alcohol. b- Ketone: From oxidation of secondary alcohol.
(7) Hydration of alkyne : Only other alkyne except acetylene will give ketone
Synthesis of aromatic ketones via Friedel-Crafts acylation: E.g. Acetophenone For benzophenone
Synthesis of benzaldehyde • Gattermann-Koch aldehyde synthesis • b) Gattermann aldehyde synthesis
Chemical reactions of aldehydes & Ketones A-Type I of reaction (Addition reaction) • تعتمد هذه التفاعلات علي إضافة H لذرة O وباقي المركب ل C • Examples of this addition is addition of HCN, H2, RMgX, HOH, NaSO3H
Some observations • يسمى ناتج إضافة HCN بذكر اسم aldehyde أو ketone متبوعاً بـ cyanohydrin. • يمكن شرح ميكانيكية إضافة HCN كالأتي • يسمى ناتج إضافة NaSO3H بذكر اسم aldehyde أو ketone متبوعاً بـ bisulphite. • إضافة NaSO3H تتم فقط علي Aldehydes أو methyl Ketones ( )
E.g. these ketones does not add NaSO3H ناتج إضافة H2O غير ثابت و يفقد H2O ثانية مكونا Aldehyde الأصلي و لكن يوجد بعض اتج إضافة H2O ثابتة مثل
Special cases of addition reactions • Benzoin condensation b) Formation of hemiacetals and acetals
B-Type II of reaction[addition reaction followed by loss of H2O] • e.g. (Condensation with amines) • أي Ald. Or Ketones يتفاعل معamines بالإضافة العادية متبوعة بفقد H2O Examples:
C-Type III of reaction(Base catalyzed reaction) 1- Aldol condensation: - It occurs between two aldehydes or two ketones containing α-Hydrogen.. Mechanism:
- Other example: Mechanism:
In case of mixture of acetaldehyde and acetone , we obtain four products Mechanism of formation of crotanaldehyde
Mechanism of formation of Mestyl oxide Mechanism of formation of 3-methyl-2-butenal
2- Cannizaro reaction: - It occurs between two aldehydes with no α-hydrogen in presence of base to give an alc. and an acid.
Question: Show the effect of NaOH on acetaldehyde and benzaldehyde 3- Clasien condensation ; 4- Perkin condensation: D-Type IV of reaction(Different types of reaction)
Oxidation of aldehyde ketones: • Aldehydes can also oxidized by Tollens reagent [Ag(NH3)2OH]. • Ketones are difficult for oxidation
Haloform reaction: • It occurs with aldehyde or ketones containing • The only aldehyde gives Iodoform reaction is acetaldehyde ) only can give iodoform only for example • Methyl ketones ( • These ketones cannot give iodoform because they do not have
Examples of iodoform equation : Mechanism: ملحوظة: يعتبر تفاعل الهالوفورم أكسدة لـ ald. او ketoneإلى حمض مع فقد ذرة كربون واحدة.
Reduction of aldehydes & Ketones: 1- Reduction by catalytic hydrogen: It converts aldehyde or ketone to alcohol.
2- Reduction to hydrocarbon: • أي تحويل ald. او ketoneإلى alkane. For examples;
a- Clemmensen reduction: b- Walf-Kishner reduction:
3- Reduction with sod. Borohydride (NaBH4): 4- Reduction with Mg:
Replacement of oxygen by halogen: • PCl3, PCl5 or SOCl2 convert C=O into Example: • PCl3, PCl5 or SOCl2 convert –OH to -Cl
The reaction of aldehyde or ketones with PCl3, PCl5 or SOCl2, can be used to convert aldehyde or ketones alkyne as follow e.g. conversion of acetone to propyne Halogenation of α-carbon:
In case of aromatic aldehyde or ketones. • In absence of Fe or FeCl3 catalyst • In this case the reaction occur at α-carbon to C=O or in H of CHO
b) In absence of Fe or FeCl3 catalyst Aldehydes and ketones are m- directing group, so orient halogen in m- position
Polymerization reaction • Only aldehydes can polymerize • Examples • a) Polymerization of formaldehyde in presence of water • B )Polymerization of formaldehyde and acetaldehyd ofpresence of H2SO4